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Nadca tolerances-2009

die casting
Published on: Mar 3, 2016
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Transcripts - Nadca tolerances-2009

  • 1. 4A-1NADCA Product Specification Standards for Die Castings / 2006 Engineering & Design: Coordinate Dimensioning 4A s e c t i o n 4ASection Contents NADCA No. Format Page Frequently Asked Questions (FAQ) 4A-2 1 Introduction 4A-2 2 Section Objectives 4A-3 3 Standard and Precision Tolerances 4A-3 4 Production Part Technologies 4A-4 5 Die Casting, SSM & Squeeze Cast Part Design 4A-6 6 Linear Dimensions Tolerances S-4A-1-09 Standard 4A-7 P-4A-1-09 Precision 4A-8 7 Parting Line Tolerances S-4A-2-09 Standard 4A-9 P-4A-2-09 Precision 4A-10 8 Moving Die Component Tolerances S-4A-3-09 Standard 4A-11 P-4A-3-09 Precision 4A-12 9 Angularity Tolerances S/P-4A-4-09 Standard/Precision 4A-13 10 Concentricity Tolerances S-4A-5-09 Standard 4A-17 11 Parting Line Shift S-4A-6-09 Standard 4A-19 12 Draft Tolerances S/P-4A-7-09 Standard/Precision 4A-21 13 Flatness Tolerances S-4A-8-09 Standard 4A-29 P-4A-8-09 Precision 4A-30 14 Design Recommendations: Cored Holes As-Cast 4A-31 15 Cored Holes for Cut Threads S-4A-9-09 Standard 4A-34 P-4A-9-09 Precision 4A-35 16 Cored Holes for Formed Threads P-4A-10-09 Precision 4A-36 17 Cored Holes for Pipe Threads S-4A-11-09 Standard 4A-38 18 Cast Threads S-4A-12-09 Standard 4A-39 19 Machining Stock Allowance S/P-4A-13-09 Standard/Precision 4A-40 20 Additional Considerations for Large Castings 4A-42 NADCA Product Specification Standards for Die Castings / 2009
  • 2. 4A-2 NADCA Product Specification Standards for Die Castings / 2006 Engineering & Design: Coordinate Dimensioning 1Frequently Asked Questions (FAQ) 1) What is the difference between Standard and Precision Tolerances? See pages 4A-3 and 4A-4, 3.0 Standard and Precision Tolerances. 2) What is a Parting Line Shift? See pages 4A-19 and 4A-20, Parting Line Shift. 3) If my casting requires machining, how should the casting be dimensioned? See page 4A-40 and 4A-41, Machining Stock Allowances. 4) How large should a cast-in hole be if threads need to be tapped or formed in the casting? See page 4A-34 and 4A-35, Cored Holes for Cut Threads. Also see pages 4A-36 and 4A-37, Cored Holes for Formed Threads. 5) What type of draft should be used on exterior and interior walls? See pages 4A-21 through 4A-24, Draft Requirements. 6) What type of flatness tolerance can be expected on a cast surface? See pages 4A-29 and 4A-30, Flatness Requirements. 1 Introduction Die casting requires a specific degree of precision for the end product to meet the requirements of form, fit and function. However there is a cost associated with increased precision. Some of the costs associated with a higher degree of tolerance include: Decreased die life due to wear that puts die dimensions outside of specified high precision tolerance• More frequent die repair or replacement to maintain a high precision tolerance• More frequent shutdown (shorter production runs) to repair or replace dies• More frequent part or die inspections to ensure high precision tolerance is maintained• Potential for higher scrap rate for not maintaining specified high precision tolerance• A good casting design will take into account not only the precision required to meet the require- ments of form, fit and function, but will also take into account maximizing tolerance to achieve a longer die life and longer production runs with less inspections. This will result in less potential for scrap and more acceptable parts because the tolerance range for acceptable parts has increased. In section 4A tolerance will be specified in two values. Standard Tolerance is the lesser degree of precision that will meet most applications of form, fit and function. It is specified in thousandths of an inch (0.001) or hundredths of a millimeter (0.01). Degree of variation from design specified values is larger than that of Precision Tolerance as shown in graphical representation at the end of section 4A. Precision Tolerance is a higher degree of precision used for special applications where form, fit and function are adversely affected by minor variations from design specifications. Precision Tolerance is also specified in thousandths of an inch or hundredths of a millimeter. However, its variation from design specified values is less than that of Standard Tolerances. Examples of tolerance application may be an engine casting that uses Standard Tolerance. Form, fit and function are not critical since moving parts will be encased in sleeves that are cast into place. Variations in size will be filled with cast metal. Standard Tolerance meets the criteria for this application as part of the design. However a gas line fit- ting may require a higher degree of precision so that mating parts fit together to prevent leaks. Precision gas fittings may cost more to produce because of the higher degree of precision that must be maintained. Degree of precision depends on the applications of form, fit and function which resides with the design engineer’s expectation of part performance. Cast components can be specified and produced to an excellent surface finish, close dimensional tolerances and to minimum draft, among other characteristics. All of the capabilities of the casting process, specified to maximum degree, will rarely, if ever, be required in one cast part. For the most economical production, the design engineer or specifier should attempt to avoid such requirements in a single component. It is important for the product designer and engineer to understand precisely how today’s die casting process can be specified in accordance with the capabilities of the die casting industry. Tolerance in any part is a three-dimensional character- istic. Many different types of tolerance will be discussed throughout sections 4A and 4B. Most feature tolerances will have Linear Tolerance in combination with Projected Area Tolerance to give an overall feature “volumetric” tolerance like Parting Line, Moving Die Component (MDC) and Angularity Tolerances. Projected Area is the area of a specific feature projected into a plane. For parting line and parting line shift the Projected Area is the open area of the die cavity in the parting line plane. For example, if a die half was laid down and filled with liquid, the surface of the liquid is the Projected Area of the parting line. For the MDC, the Projected Area is determined using the same method as for a parting line. See the applicable figures in the appropriate sections for Projected Area. Linear Tolerance is calculated from a line perpendicular to any feature. The Parting Line line is the total depth of molten material on both die halves, which is perpendicular to the parting line plane. The MDC line is the length of the core slide which is perpendicular to the head of the core slide. Length of a core slide is determined from the point where the core first engages the die to its full insertion point. Projected Area Tolerance plus Linear Tolerance equals feature tolerance (tolerance of the volume of the part). See Volumetric Tolerance diagram on the facing page. NADCA Product Specification Standards for Die Castings / 2009
  • 3. 4A-3NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning 4A Volume = 7.39 in^3 2 Section Objectives The Engineering and Design Sections of this document are prepared to aid product specifiers in achieving the most cost-effective results through net-shape and near-net-shape casting production. They present both English and Metric values on the same page. Section 4A presents standard/precision tolerances and other specifications for die cast parts ranging from a fraction of an inch (several millimeters) to several feet (meter) in size. Material weight ranges from a fraction of an ounce (several milligrams) to thirty pounds (kilograms) or more. Section 4B presents standard/precision tolerances and other specifications for miniature die cast parts ranging from hundredths of an inch (tenths of a millimeter) to several inches (several centimeters) in size. Material weights ranging from a fraction of an ounce (several milligrams) to about 16 ounces (454 grams). Section 5 presents Geometric Dimensioning, which provides guidelines for applying tolerances to cast part specifications. These sections provide information for developing the most economically produced design that meets the specifications of form, fit and function. 3 Standard and Precision Tolerances As noted in the contents for this section, seven important sets of tolerancing guidelines are presented here as both “Standard” and “Precision” Tolerances: Linear dimensions• Dimensions across parting Lines• Dimensions formed by moving die components (MDC)• Angularity• Draft• Flatness• Cored holes for threads• The following features are only specified in Standard Tolerance. Unlike the features above, parts that exceed the following tolerances will not meet the requirements of form, fit and function. These features are specified at the maximum tolerance to meet their requirements. These features include: Concentricity• Parting Line Shift• Volumetric Tolerance for Across Parting Line Features (See diagram on this page.) Parting Line Projected Area is defined by the horizontal center line shown in the figure below. Its dimensions are 1.00 inch wide by (7.50 - 1.50) inches long. The Projected area is (1.00 x 6.00) or 6.00 in. sq. This is the surface area used for features across the parting line. Tolerance is expressed in inches. Linear Dimension (depth of cavity on both die halves) is 1.50 inches. This is the linear dimension used to determine Linear Tolerance. Feature Tolerance is Projected Area Tolerance plus Linear Area Tolerance. Graphical Representation Throughout section 4A there is graphical representation of specific feature tolerances. Precision tolerances are generally closer to design specifications than standard tolerances. The x-axis along y-axis at zero indicates actual design specification. Graph lines indicate the maximum allowable deviation from design specification. NADCA Product Specification Standards for Die Castings / 2009
  • 4. 4A-4 NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning Fig. 4A-1 Proposed component. Standard Tolerances Standard Tolerances cover expected values consistent with high casting cycle speeds, uninter- rupted production, reasonable die life and die maintenance costs, as well as normal inspection, packing and shipping costs. Such tolerances can normally be achieved by the widely available production capabilities of casters practicing standard methods and procedures. Conformity to these standards by designers assures the most predictable service and lowest cost. Precision Tolerances Critical requirements for dimensional accuracy, draft, etc.., beyond the Standard Tolerances presented, can be specified when required. Precision Tolerances are presented on the page facing the Standard Tolerances for the same characteristic. The values shown for Precision Tolerances represent greater casting accuracy. See graphical comparison of Standard and Precision Tolerances throughout section 4A. Part preci- sion tolerances involve extra precision in die construction and/or special process controls during production. The use of new technologies and equipment aid in maintaining Precision Tolerance. While early consultation with the caster can result in selected special precision requirements being incorporated with little additional cost, such tolerances should be specified only where necessary. It should be noted that the tolerances shown must, of necessity, be guidelines only—highly dependent on the particular shape, specific features and wall thickness transitions of a given part design. These factors, under the control of the product designer, greatly influence the ability of the casting process to achieve predetermined specifications in the final cast part. Where a number of critical requirements are combined in a single casting, early caster evalu- ation of a proposed design is essential. Design modifications for more cost-efficient casting can nearly always be made. Without such feedback, additional costs can usually be expected and the design, as originally planned, may be not be producible by die casting. When specific designs are examined, tolerances even closer than the Precision Tolerances shown can often be held by repeated production sampling and recutting of the die casting die, together with production capability studies. While such steps will result in additional tooling and production costs, the significant savings that can result by eliminating substantial secondary machining and/or finishing operations can prove highly cost effective. 4 Production Part Technologies This section presents advantages and limitations of various production technologies for a simple part such as the one shown in Fig. 4A-1. The section that follows presents the die cast alternative and its advantages and limitations. Metal Stamping Alternative This part design, as pictured in the side profile Fig. 4A-1 and if designed to a minimum thickness without additional complexities, could be considered for volume production by the metal stamping process. Metal stamping lends itself to high-speed production with infrequent die replacement or repair. However, the stamping process can only produce features that are apparent on both sides of a thin part. Indentations on one side of the part appear as ridges on the other side of the part. Critical NADCA Product Specification Standards for Die Castings / 2009
  • 5. 4A-5NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning 4A Fig. 4A-1A Proposed component with added features and design modified for cost-effective die casting production, showing orientation in the die casting die and core slide (moving die component) to cast the additional features. bends in the metal surface of stamped products become areas of weakness where metal is yielded to make the bend. Complex features within the layer of metal are impossible without additional stamped parts and assembly. Thicker parts require higher stamping pressure which compounds metal fatigue at critical bends. This is similar to a large tree snapping in the wind where a sapling will bend. Multiple stamped layers and assembly would exceed the cost of the die cast alternative. Extrusion Alternative If the part design required stock depth beyond stamping capabilities, the extrusion process might be a production alternative for creating such a profile—unless complex additional interior features were desirable, such as those shown in Fig. 4A-1. When total costs of a product assembly can be significantly reduced by a more robust part design, as that suggested by Fig. 4A-1, the production process which allows such design freedom is the better choice. The extrusion process produces a uniform internal structure in one axis such as a bar or a tube. End features or variations within the axis are impossible. A part, such as the one shown in Fig. 4A-1, has design feature variations on all axes therefore extrusion of this part is not possible without multiple operations which would exceed the cost of the die cast alternative. Machining Alternative Automated machining could produce product features as shown in Fig. 4A-1. Complex features would require additional operations for each piece. This would be very time consuming and would place tremendous wear on production equipment especially during large volume production. As volumes increased, machining would become a very high-cost production option. Foundry Casting Alternative Foundry casting plus secondary machining might be an alternative for this part. Foundry casting involves pouring molten metal into a mold. Without the pressure of die, SSM or squeeze casting to force metal into critical paths, around tight turns, and into small features of the mold, Foundry casting can not achieve the detail and precision of die, SSM or squeeze casting. The Foundry casting process is relatively slow in that gravity fills and mold positions take time to achieve. Extensive secondary machining is required for Foundry castings when close tolerances are required. This is not only costly but time consuming. Foundry casting is usually reserved for large iron castings with very little intricate detail. It is not considered as a high volume process. Net- shape die casting can become the more cost-effective solution, often at low production volumes. NADCA Product Specification Standards for Die Castings / 2009
  • 6. 4A-6 NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning Investment Casting Alternative At low volumes the investment casting process could be considered to achieve precision toler- ances. At higher volumes die casting would be the clear choice. Powdered Metal Alternative The powdered metal process offers dimensional accuracy for many parts. It cannot achieve the more complex configurations, detailed features or thinner walls which die casting can easily produce to net-or near-net shape. Plastic Molded Alternative Plastic injection molding could achieve the designed configuration shown in Fig. 4A-1, but if requirements of rigidity, creep resistance, and strength—particularly at elevated temperatures— were important, plastics would be questionable. The longevity of plastic components is normally substantially less than that of metal components. Plastics products are subject to failure modes such as sunlight, radiation, heat and various chemicals. The designer needs to ensure that the application and duration of the end product will meet the customers needs and expectations. Additionally, the preference for use of a recycled raw material as well as the potential for eventual recycling of the product at the end of its useful life would also support a decision for die casting. 5 Die Casting, SSM and Squeeze Cast Part Design Fig. 4A-1A, illustrates a good design practice for die, SSM and squeeze casting production. Sharp corners have been eliminated and the design has been provided with the proper draft and radii to maximize the potential die life and to aid in filling the die cavity completely under high production cycle speeds. Typical wall thicknesses for a cast design range from 0.040 in. (1.016 mm) to 0.200 in. (5.08 mm), depending on alloy, part configuration, part size and application. Smaller castings with wall sections as thin as 0.020 in. (0.50 mm) can be cast, with die caster consulta- tion. For extremely small zinc parts, miniature die casting technology can be used to cast still thinner walls. See section 4B for information on miniature die casting. Fig. 4A-1 will be used elsewhere in this section to present dimensional tolerances, specifically as they relate to part dimensions on the same side of the die half, across the parting line, and those formed by moving die components. Fig. 4A-1 will also be used in the Geometric Dimensioning Section to show how datum structure can influ- ence tooling and tolerances. NADCA Product Specification Standards for Die Castings / 2009
  • 7. 4A-7NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning 4A 6 Linear Dimensions: Standard Tolerances The Standard Tolerance on any of the features labeled in the adjacent drawing, dimension “E1” will be the value shown in table S-4A-1 for dimensions between features formed in the same die part. Tolerance must be increased for dimensions of features formed by the parting line or by moving die parts to allow for movement such as parting line shift or the moving components in the die itself. See tables S-4A-2 and S-4A-3 for calculating precision of moving die components or parting line shift. Linear tolerance is only for fixed components to allow for growth, shrinkage or minor imperfections in the part. Tolerance precision is the amount of variation from the part’s nominal or design feature. For example, a 5 inch design specification with ±0.010 tolerance does not require the amount of precision as the same part with a toler- ance of ±0.005. The smaller the tolerance number, the more precise the part must be (the higher the precision). Normally, the higher the precision the more it costs to manufacture the part because die wear will affect more precise parts sooner. Production runs will be shorter to allow for increased die maintenance. Therefore the objective is to have as low precision as possible without affecting form, fit and function of the part. Example: An aluminum casting with a 5.00 in. (127 mm) specification in any dimension shown on the drawing as “E1”, can have a Standard Tolerance of ±0.010 inch (±0.25 mm) for the first inch (25.4 mm) plus ±0.001 for each additional inch (plus ±0.025 mm for each additional 25.4 mm). In this example that is ±0.010 for the first inch plus ±0.001 multiplied by the 4 additional inches to yield a total tolerance of ±0.014. In metric terms, ±0.25 for the first 25.4 mm increments plus ±0.025 multiplied by the 4 additional 25.4 mm to yield a total tolerance of ±0.35 mm for the 127 mm design feature specified as “E1” on the drawing. Linear dimension tolerance only applies to linear dimensions formed in the same die half with no moving components. NADCA S-4A-1-09 STANDARD TOLERANCES The values shown represent Standard Tolerances, or normal casting production practice at the most economical level. For greater casting accuracy see Precision Tolerances for this characteristic on the facing page. Be sure to also address the procedures referred to in Section 7, “Quality Assurance,” sub-section 3, 4 and 5. Significant numbers indicate the degree of accuracy in calculating precision. The more significant numbers in a specified tolerance, the greater the accuracy. Significant number is the first non-zero number to the right of the decimal and all numbers to the right of that number. For example, 0.014. The degree of accuracy is specified by the three significant numbers 140. This is not to be confused with tolerance precision. A tolerance limit of 0.007 has a higher degree of precision because it is closer to zero tolerance. Zero tolerance indicates that the part meets design specifications exactly. Linear Standard and Linear Precision tolerances are expressed in thousandths of an inch (.001) or hundredths of a millimeter (.01). Notes: Casting configuration and shrink factor may limit some dimension control for achiev- ing a specified precision. Linear tolerances apply to radii and diameters as well as wall thicknesses. Casting Alloys Zinc ±0.010 (±0.25 mm) ±0.001 (±0.025 mm) Aluminum ±0.010 (±0.25 mm) ±0.001 (±0.025 mm) Magnesium ±0.010 (±0.25 mm) ±0.001 (±0.025 mm) Copper ±0.014 (±0.36 mm) ±0.003 (±0.076 mm) Table S-4A-1 Tolerances for Linear Dimensions (Standard) In inches, two-place decimals (.xx); In millimeters, single-place decimals (.x) Length of Dimension E1 Basic Tolerance up to 1 (25.4mm) Additional Tolerance for each additional inch over 1 (25.4mm) PL E1 E1 NADCA Product Specification Standards for Die Castings / 2009
  • 8. 4A-8 NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning Linear Dimensions: Precision Tolerances Precision Tolerance on any of the features labeled in the adjacent drawing, dimension “E1” will be the value shown in table P-4A-1 for dimensions between features formed in the same die part. Tolerance must be increased for dimensions of features formed by the parting line or by moving die parts to allow for movement such as parting line shift or the moving components in the die itself. See tables P-4A-2 and P-4A-3 for calculating precision of moving die components or parting line shift. Linear tolerance is only for fixed components to allow for growth, shrinkage or minor imperfections in the part. Example: An aluminum die casting with a 5.00 in. (127 mm) specification in any dimension shown on the drawing as “E1”, can have a Precision Tolerance of ±0.002 inches (±0.05 mm) for the first inch (25.4 mm) plus ±0.001 for each additional inch (plus ±0.025 mm for each additional 25.4 mm). In this example that is ±0.002 for the first inch plus ±0.001 multiplied by the 4 additional inches to yield a total tolerance of ±0.006. In metric terms, ±0.05 for the first 25.4 mm plus ±0.025 multiplied by the 4 additional 25.4 mm increments to yield a total toler- ance of ±0.15 mm for the 127 mm design feature specified as “E1” on the drawing. Linear dimension tolerance only applies to linear dimensions formed in the same die half with no moving components. NADCA P-4A-1-09 PRECISION TOLERANCES The Precision Tolerance values shown represent greater casting accuracy involving extra precision in die construction and/or special control in production. They should be specified only when and where necessary, since additional costs may be involved. Be sure to also ad- dress the procedures referred to in Section 7, “Quality Assurance,” sub-section 3, 4 and 5. Linear tolerances apply to radii and diameters as well as wall thicknesses. Methods for Improving Precision: 1. By repeated sampling and recutting of the die cast tool, along with capability studies, even closer dimensions can be held. However, additional sampling and other costs may be incurred. 2. For zinc die castings, tighter tolerances can be held, depending on part configuration and the use of artificial aging. Artificial aging (also known as heat treating) may be essential for main- taining critical dimensions in zinc, particularly if the part is to be machined, due to the creep (growth) characteristics of zinc. The die caster should be consulted during the part design stage. 3. In the case of extremely small zinc parts, weighing fractions of an ounce, special die casting machines can achieve significantly tighter tolerances, with zero draft and flash-free operation. See Section 4B, Miniature Die Casting. PL E1 E1 Casting Alloys Zinc ±0.002 (±0.05 mm) ±0.001 (±0.025 mm) Aluminum ±0.002 (±0.05 mm) ±0.001 (±0.025 mm) Magnesium ±0.002 (±0.05 mm) ±0.001 (±0.025 mm) Copper ±0.007 (±0.18 mm) ±0.002 (±0.05 mm) Table P-4A-1 Tolerances for Linear Dimensions (Precision) In inches, three-place decimals (.xxx); In millimeters, two-place decimals (.xx) Length of Dimension E1 Basic Tolerance up to 1 (25.4mm) Additional Tolerance for each additional inch over 1 (25.4mm) Al, Mg, Zn Stand. Tol. Cu Stand. Tol. Al, Mg, Zn Precis. Tol. Cu Precis. Tol. Linear Tolerance 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 1 (25.4) 2 (50.8) 3 (76.2) 4 (101.6) 5 (127.0) 6 (152.4) 7 (177.8) 8 (203.2) 9 (228.6) 10 (254.0) 11 (279.4) 12 (304.8) Linear Dimension in Inches (mm) Tolerancein+/-Inches NADCA Product Specification Standards for Die Castings / 2009
  • 9. 4A-9NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning 4A 7 Parting Line: Standard Tolerances Parting Line Tolerance is the maximum amount of die separation allowed for the end product to meet specified requirements of form, fit and function. This is not to be confused with Parting Line Shift Tolerance which is the maximum amount die halves shift from side to side in relation to one another. An example of Parting Line Tolerance is the amount a door is allowed to be opened and still call it closed. An example of Parting Line Shift Tolerance is how well the door fits in the frame. Worn hinges may cause the door to drag on the floor so that it can not be closed and therefore not perform its intended function. Parting Line Shift Tolerance will be discussed later in this section. Parting Line Tolerance is a function of the surface area of the die from which material can flow from one die half to the other. This is also known as Projected Area. Projected Area is always a plus tolerance since a completely closed die has 0 separation. Excess material and pressure will force the die to open along the parting line plane creating an oversize condition. The excess material will cause the part to be thicker than the ideal specification and that is why Projected Area only has plus tolerance. It is important to understand that Table S-4A-2 (Projected Area Tolerance) does not provide Parting Line Tolerance by itself. Part thickness or depth must be factored in to give a true idea of Parting Line Tolerance. Parting Line Tolerance is a function of part thickness perpendicular to the Projected Area plus the Projected Area Tolerance. Part thickness includes both die halves to give a volumetric representation of Parting Line Toler- ance. Information from the Projected Area Tolerance table S-4A-2 in combination with the formerly discussed Linear Tolerance table S-4A-1 give a true representation of Parting Line Tolerance. Note that the tolerances in the table apply to a single casting regardless of the number of cavities. Example: An aluminum die casting has 75 in2 (483.9 cm2 ) of Projected Area on the parting die plane. From table S-4A-2, Projected Area Tolerance is +0.012. This is combined with the total part thickness tolerance from table S-4A-1 to obtain the Parting Line Tolerance. The total part thickness including both die halves is 5.00 in. (127 mm) which is measured per- pendicular to the parting die plane (dimension “E2 E1”). From table S-4A-1, the Linear Tolerance is ±0.010 for the first inch and ±0.001 for each of the four additional inches. The Linear Tolerance of ±0.014 inches is combined with the Projected Area Tolerance of +0.012 to yield a Standard Parting Line Tolerance of +0.026/-0.014 in. or in metric terms ±0.35 mm from Linear Tolerance table S-4A-1 plus +0.30 mm from Projected Area Tolerance table S-4A-2 = +0.65/-0.35 mm. NADCA S-4A-2-09 STANDARD TOLERANCES The values shown represent Standard Tolerances, or normal die casting produc- tion practice at the most economical level. For greater casting accuracy see Precision Tolerances for this characteristic on the facing page. Be sure to also address the procedures referred to in Section 7, “Quality Assurance,” sub-section 3, 4 and 5. Die Shift: Parting line die shift, unlike parting line separation and moving die component tolerances, is a left/right relationship with possible ± consequences. It can shift in four directions, based on a combination of part features, die construction and operation factors. It can occur at any time and its tolerance consequences should be discussed with the die caster at the design stage to minimize any impact on the final die casting. Notes: All values for part dimensions which run across the die parting line are stated as a “plus” tolerance only. The die casting die at a die closed position creates the bottom of the tolerance range, i.e., 0.000 (zero). Due to the nature of the die casting process, dies can separate imperceptibly at the parting line and create only a larger, or “plus” side, tolerance. Casting Alloys (Tolerances shown are plus values only) Zinc +0.0045 (+0.114 mm) +0.005 (+0.13 mm) +0.006 (+0.15 mm) +0.009 (+0.23 mm) +0.012 (+0.30 mm) +0.018 (+0.46 mm) Aluminum +0.0055 (+0.14 mm) +0.0065 (+0.165 mm) +0.0075 (+0.19 mm) +0.012 (+0.30 mm) +0.018 (+0.46 mm) +0.024 (+0.61 mm) Magnesium +0.0055 (+0.14 mm) +0.0065 (+0.165 mm) +0.0075 (+0.19 mm) +0.012 (+0.30 mm) +0.018 (+0.46 mm) +0.024 (+0.61 mm) Copper +0.008 (+0.20 mm) +0.009 (+0.23 mm) +0.010 (+0.25 mm) Table S-4A-2 Parting Line Tolerances (Standard) — Added to Linear Tolerances For projected area of die casting over 300 in2 (1935.5 cm2), consult with your die caster. Projected Area of Die Casting inches2 (cm2) up to 10 in2 (64.5 cm2) 11 in2 to 20 in2 (71.0 cm2 to 129.0 cm2) 21 in2 to 50 in2 (135.5 cm2 to 322.6 cm2) 51 in2 to 100 in2 (329.0 cm2 to 645.2 cm2) 101 in2 to 200 in2 (651.6 cm2 to 1290.3 cm2) 201 in2 to 300 in2 (1296.8 cm2 to 1935.5 cm2) NADCA Product Specification Standards for Die Castings / 2009
  • 10. 4A-10 NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning Parting Line: Precision Tolerances Precision Tolerances on dimensions such as “E2 E1”, which are perpendicular to (across) the die parting line, will be the linear dimension tolerance from table P-4A-1 plus the value shown in table P-4A-2. The value chosen from the table below depends on the “projected area” of the part, in inches squared or millimeters squared, in the plane of the die parting. Note that the tolerances shown below are “plus side only” and based on a single cavity die casting die. Example: An aluminum die casting has 75 in2 (483.9 cm2 ) of Projected Area on the parting die plane. From table P-4A-2, Projected Area Tolerance is +0.008. This is combined with the total part thickness from table P-4A-1 to obtain the Parting Line Tolerance. Total part thickness including both die halves is 5.000 in. (127 mm) which is measured perpendicular to the parting die plane (dimension “E2 E1”). From table P-4A-1, the Linear Tolerance is ±0.002 for the first inch and ±0.001 for each of the four additional inches. The Linear Tolerance of ±0.006 is combined with the Projected Area Tolerance of +0.008 to yield a Precision Parting Line Tolerance of +0.014/-0.006 in. or in metric terms (±0.15 mm plus +0.20 mm) = +0.35/-0.15 mm on dimensions that are formed across the parting line. Die Casting Alloys (Tolerances shown are plus values only) Zinc +0.003 (+0.076 mm) +0.0035 (+0.089 mm) +0.004 (+0.102 mm) +0.006 (+0.153 mm) +0.008 (+0.203 mm) +0.012 (+0.305 mm) Aluminum +0.0035 (+0.089 mm) +0.004 (+0.102 mm) +0.005 (+0.153 mm) +0.008 (+0.203 mm) +0.012 (+0.305 mm) +0.016 (+0.406 mm) Magnesium +0.0035 (+0.089 mm) +0.004 (+0.102 mm) +0.005 (+0.153 mm) +0.008 (+0.203 mm) +0.012 (+0.305 mm) +0.016 (+0.406 mm) Copper +0.008 (+0.20 mm) +0.009 (+0.23 mm) +0.010 (+0.25 mm) Table P-4A-2 Parting Line Tolerances (Precision) — Added to Linear Tolerances For projected area of die casting over 300 in2 (1935.5 cm2), consult with your die caster. Projected Area of Die Casting inches2 (cm2) up to 10 in2 (64.5 cm2) 11 in2 to 20 in2 (71.0 cm2 to 129.0 cm2) 21 in2 to 50 in2 (135.5 cm2 to 322.6 cm2) 51 in2 to 100 in2 (329.0 cm2 to 645.2 cm2) 101 in2 to 200 in2 (651.6 cm2 to 1290.3 cm2) 201 in2 to 300 in2 (1296.8 cm2 to 1935.5 cm2) PL E2 E1 Al, Mg Stand. Tol. Cu Stand. Tol. Zn Stand. Tol. Al, Mg Precis. Tol. Cu Precis. Tol. Zn Precis. Tol. Parting Line Tolerances 0 0.005 0.01 0.015 0.02 0.025 0.03 10 (64.50) 20 (129.0) 50 (322.6) 100 (645.2) 200 (1290) 300 (1935) Projected Area in Inches Square (cm sq) Tolerancein+Inches NADCA P-4A-2-09 PRECISION TOLERANCES The Precision Tolerance values shown represent greater casting accuracy involving extra precision in die construction and/or special control in production. They should be specified only when and where necessary, since additional costs may be involved. Be sure to also ad- dress the procedures referred to in Section 7, “Quality Assurance,” sub-section 3, 4 and 5. Methods for Improving Precision: 1. By repeated sampling and recutting of the die cast tool, along with capability studies, even closer dimensions can be held. However, additional sampling and other costs may be incurred. 2. For zinc die castings, tighter tolerances can be held, depending on part configuration and the use of artificial aging. Artificial aging (also known as heat treating) may be essential for main- taining critical dimensions in zinc, particularly if the part is to be machined, due to the creep (growth) characteristics of zinc. The die caster should be consulted during the part design stage. 3. In the case of extremely small zinc parts, weighing fractions of an ounce, special die casting machines can achieve significantly tighter tolerances, with zero draft and flash-free operation. See Section 4B, Miniature Die Casting. NADCA Product Specification Standards for Die Castings / 2009
  • 11. 4A-11NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning 4A 8 Moving Die Components (MDC): Standard Tolerances Moving Die Components Tolerance can affect final part performance similar to Parting Line Tolerance. When the core is fully inserted into the die, the minimum tolerance is zero. As excess material and pressure are exerted in the die, the core can slide out creating an oversized condition. A MDC Tolerance has been developed to ensure minimal impact on form, fit and function by specifying limits to the oversize condition. Similar to Parting Line Tolerance, MDC Standard Tolerance is a function of the Projected Area Tolerance plus Linear Tolerance. Linear Tolerance is calculated based on the length of movement of the core slide along dimen- sion “E3 E1”. Table S-4A-1 is used to determine Linear Tolerance. The linear dimension is not the entire length of “E3 E1” but is only the length of the core slide from where the core slide first engages the die to its full insertion position. Linear dimension is normally perpendicular to the Projected Area. Projected Area is the area of the core head that faces the molten material. Projected Area Tolerance for moving die components is determined from table S-4A-3. The open area (cavity) on the end view of the part in figure 4A-1A at the beginning of this section shows the projected area. Projected Area Tolerance plus Linear Tolerance provide MDC Standard Tolerance for the volume of the part. Note that the tolerances in the table apply to a single casting regardless of the number of cavities. Example: An aluminum casting has 75 in2 (483.9 cm2 ) of Projected Area calculated from the core slide head facing the molten material. From table S-4A-3, Projected Area Tolerance is +0.024. This is combined with the length of the core slide Linear Tolerance from table S-4A-1 to obtain the MDC Standard Tolerance. The total core slide length of 5.00 in. (127 mm) is measured from where the core engages the part to full insertion in the plane of dimension “E3 E1” to determine Linear Tolerance length. From table S-4A-1, the Linear Tolerance is ±0.010 for the first inch and ±0.001 for each of the four additional inches. The Linear Tolerance of ±0.014 inches is combined with the Projected Area Tolerance of +0.024 to yield a MDC Standard Tolerance of +0.038/-0.014 in. MDC Metric Standard Tolerance is +0.96/-0.35 mm = (±0.35 mm) + (+0.61 mm) on dimensions formed by moving die components. Die Casting Alloys (Tolerances shown are plus values only) Zinc +0.006 (+0.15 mm) +0.009 (+0.23 mm) +0.013 (+0.33 mm) +0.019 (+0.48 mm) +0.026 (+0.66 mm) +0.032 (+0.81 mm) Aluminum +0.008 (+0.20 mm) +0.013 (+0.33 mm) +0.019 (+0.48 mm) +0.024 (+0.61 mm) +0.032 (+0.81 mm) +0.040 (+0.1 mm) Magnesium +0.008 (+0.20 mm) +0.013 (+0.33 mm) +0.019 (+0.48 mm) +0.024 (+0.61 mm) +0.032 (+0.81 mm) +0.040 (+0.1 mm) Copper +0.012 (+0.305 mm) Table S-4A-3 MDC Tolerances (Standard) — Added to Linear Tolerances For projected area of die casting over 300 in2 (1935.5 cm2), consult with your die caster. Projected Area of Die Casting inches2 (cm2) up to 10 in2 (64.5 cm2) 11 in2 to 20 in2 (71.0 cm2 to 129.0 cm2) 21 in2 to 50 in2 (135.5 cm2 to 322.6 cm2) 51 in2 to 100 in2 (329.0 cm2 to 645.2 cm2) 101 in2 to 200 in2 (651.6 cm2 to 1290.3 cm2) 201 in2 to 300 in2 (1296.8 cm2 to 1935.5 cm2) PL E3 E Core Slide 1 NADCA S-4A-3-09 STANDARD TOLERANCES The values shown represent Standard Tolerances, or normal die casting produc- tion practice at the most economical level. For greater casting accuracy see Precision Tolerances for this characteristic on the facing page. Be sure to also address the procedures referred to in Section 7, “Quality Assurance,” sub-section 3, 4 and 5. Die Shift: Parting line die shift, unlike parting line separation and moving die component tolerances, is a left/right relationship with possible ± consequences. It can shift in four directions, based on a combination of part features, die construction and operation factors. It can occur at any time and its tolerance consequences should be discussed with the die caster at the design stage to minimize any impact on the final die casting. Notes: All values for part dimensions which run across the die parting line are stated as a “plus” tolerance only. The die casting die at a die closed position creates the bottom of the tolerance range, i.e., 0.000 (zero). Due to the nature of the die casting process, dies can separate imperceptibly at the parting line and create only a larger, or “plus” side, tolerance. NADCA Product Specification Standards for Die Castings / 2009
  • 12. 4A-12 NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning Moving Die Components (MDC): Precision Tolerances Precision Tolerances attainable on die cast dimensions such as “E3 E1” formed by a moving die component will be the linear tolerance from table P-4A-1 plus the value shown in table P-4A-3. Linear Tolerance is the length of the core slide. Projected Area is the area of the head of the core slide facing the molten material. The value chosen from table P-4A-3 depends on the Projected Area of the portion of the die casting formed by the moving die component (MDC) perpendicular to the direction of movement. Note that tolerances shown are plus side only. Example: An aluminum die casting has 75 in2 (483.9 cm2 ) of Projected Area calculated from the core slide head facing the molten material. From table P-4A-3, Projected Area Tolerance is +0.018. This is combined with the length of the core slide Linear Tolerance from table P-4A-1 to obtain the MDC Precision Tolerance. The total core slide length of 5.00 in. (127 mm) is measured from where the core engages the part to full insertion in the plane of dimension “E3 E1” to determine Linear Tolerance length from table P-4A-1, the Linear Tolerance is ±0.002 for the first inch and ±0.001 for each of the four additional inches. The Linear Tolerance of ±0.006 inches is combined with the Projected Area Tolerance of +0.018 to yield a MDC Precision Tolerance of +0.024/-0.006 in. MDC Metric Precision Tolerance is +0.607/-0.15 mm = (±0.15 mm) +(+0.457 mm) on dimensions formed by MDC. Die Casting Alloys (Tolerances shown are plus values only) Zinc +0.005 (+0.127 mm) +0.007 (+0.178 mm) +0.010 (+0.254 mm) +0.014 (+0.356 mm) +0.019 (+0.483 mm) +0.024 (+0.61 mm) Aluminum +0.006 (+0.152 mm) +0.010 (+0.254 mm) +0.014 (+0.356 mm) +0.018 (+0.457 mm) +0.024 (+0.61 mm) +0.030 (+0.762 mm) Magnesium +0.005 (+0.127 mm) +0.007 (+0.178 mm) +0.010 (+0.254 mm) +0.014 (+0.356 mm) +0.019 (+0.483 mm) +0.024 (+0.61 mm) Copper +0.010 (+0.254 mm) Table P-4A-3 MDC Tolerances (Precision) — Added to Linear Tolerances For projected area of die casting over 300 in2 (1935.5 cm2), consult with your die caster. Projected Area of Die Casting inches2 (cm2) up to 10 in2 (64.5 cm2) 11 in2 to 20 in2 (71.0 cm2 to 129.0 cm2) 21 in2 to 50 in2 (135.5 cm2 to 322.6 cm2) 51 in2 to 100 in2 (329.0 cm2 to 645.2 cm2) 101 in2 to 200 in2 (651.6 cm2 to 1290.3 cm2) 201 in2 to 300 in2 (1296.8 cm2 to 1935.5 cm2) Al, Mg Stand. Tol. Cu Stand. Tol. Zn Stand. Tol. Al Precis. Tol. Cu Precis. Tol. Mg, Zn Precis. Tol. Moving Die Tolerance 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 10 (64.5) 20 (129.0) 50 (322.6) 100 (645.2) 200 (1290.) 300 (1935.) Tolerancein+Inches Projected Area in Inches Square (cm sq) PL E 3 E Core Slide 1 NADCA P-4A-3-09 PRECISION TOLERANCES Precision Tolerance values shown represent greater casting accuracy involving extra precision in die construction and/or special control in production. They should be specified only when and where necessary, since additional costs may be involved. Be sure to also ad- dress the procedures referred to in Section 7, “Quality Assurance,” sub-section 3, 4 and 5. Methods for Improving Precision: 1. By repeated sampling and recutting of the die casting tool, along with production capability studies, even closer dimensions can be held—at additional sampling or other costs. 2. The die casting process may cause variations to occur in parting line separation. Thus, tolerances for dimensions that fall across the parting line on any given part should be checked in multiple locations, i.e., at four corners and on the center line. 3. In the case of extremely small zinc parts, weighing fractions of an ounce, special die casting machines can achieve significantly tighter toler- ances, with zero draft and flash-free operation. See section 4B Miniature Die Casting. NADCA Product Specification Standards for Die Castings / 2009
  • 13. 4A-13NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning 4A 9 Angularity Tolerances (Plane surfaces): Standard Precision Tolerances Angularity refers to the angular departure from the designed relationship between elements of the die casting. Angularity includes, but is not limited to, flatness, parallelism and perpendicular- ity. The angular accuracy of a die casting is affected by numerous factors including size of the die casting, the strength and rigidity of the die casting and die parts under conditions of high heat and pressure, position of moving die components, and distortion during handling of the die casting. Angularity is not a stand alone tolerance. Angularity Tolerance is added to other part feature tolerances. For example, if determining tolerance for angular features at the Parting Line, Parting Line Tolerance and Angularity Tolerance would be added to yield total part tolerance. Angularity is calculated from the following tables based on the surface length that is impacted by angularity and where the surface is located. There are four tables for calculating Standard and Precision Angularity Tolerance. Table S/P-4A-4A provides Angularity Tolerance for features in the same die half. Table S/P-4A-4B provides Angularity Tolerance for features that cross the parting line. Table S/P-4A-4C provides Angularity Tolerance for MDC features that are in the same die half. Table S/P-4A-4D provides Angularity Tolerance for multiple MDC features or MDC features that cross the parting line. The more MDCs involved, the more tolerance is necessary hence multiple tables. Applicability of Standard This standard may be applied to plane surfaces of die castings for all alloys. Its tolerances are to be considered in addition to those provided by other standards. Angularity Tolerances - All Alloys Tolerances required vary with the length of the surface of the die casting and the relative location of these surfaces in the casting die. Type Surfaces 3” (76.2 mm) or less Each 1” (25.4 mm) over 3” (76.2 mm) Standard .005 (.13 mm) .001 (.025 mm) Precision .003 (.08 mm) .001 (.025 mm) DATUM ASURFACE B Standard Tol. Precision Tol. Fixed Angularity Tolerance Same Die Half 0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016 3 (76.2) 4 (101.6) 5 (127.0) 6 (152.4) 7 (177.8) 8 (203.2) 9 (228.6) 10 (254.0) 11 (279.4) 12 (304.8) Linear Surface in Inches (mm) ToleranceinInches NADCA S/P-4A-4-09 STANDARD /PRECISION TOLERANCES Standard Tolerances shown represent normal die casting production practice at the most economical level. Precision Tolerance values shown represent greater casting accuracy involving extra precision in die construction and/or special control in production. They should be specified only when and where necessary, since additional costs may be involved. NADCA Product Specification Standards for Die Castings / 2009
  • 14. 4A-14 NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning Angularity Tolerances (Plane surfaces): Standard Precision Tolerances Example: Standard Tolerances — Surface -B- and the datum plane -A- are formed by the same die half. If surface -B- is 5” (127 mm) long it will be parallel to the datum plane -A- within .007 (.18 mm). [.005 (.13 mm) for the first 3” (76.2 mm) and .002 (.05 mm) for the additional length.] Example: Precision Tolerances — Surface -B- and the datum plane -A- are formed by the same die half. If surface -B- is 5” (127 mm) long it will be parallel to the datum plane -A- within .005 (.13 mm). [.003 (.08 mm) for the first 3” (76.2 mm) and .002 (.05 mm) for the additional length.] Example: For Standard Tolerances — Surface -B- and the datum plane -A- are formed in opposite die sec- tions. If surface -B- is 7” (177.8 mm) long it will be parallel to the datum plane -A- within .014 (.36 mm). [.008 (.20 mm) for the first 3” (76.2 mm) and .006 (.15 mm) for the additional length.] Example: For Precision Tolerances — Surface -B- and the datum plane -A- are formed in opposite die sec- tions. If surface -B- is 7” (177.8 mm) long it will be parallel to the datum plane -A- within .009 (.23 mm). [.005(.13 mm) for the first 3” (76.2 mm) and .004 (.10 mm) for the additional length.] Type Surfaces 3” (76.2 mm) or less Each 1” (25.4 mm) over 3” (76.2 mm) Standard .008 (.20 mm) .0015 (.038 mm) Precision .005 (.13 mm) .001 (.025 mm) DATUM A SURFACE B Standard Tol. Precision Tol. Fixed Angularity Tolerance Across PL 0 0.005 0.01 0.015 0.02 0.025 3 (76.2) 4 (101.6) 5 (127.0) 6 (152.4) 7 (177.8) 8 (203.2) 9 (228.6) 10 (254.0) 11 (279.4) 12 (304.8) Linear Surface in Inches (mm) ToleranceinInches NADCA S/P-4A-4-09 STANDARD /PRECISION TOLERANCES Precision Tolerance values shown represent greater casting accuracy involving extra precision in die construction and/or special control in production. They should be specified only when and where necessary, since additional costs may be involved. Methods for Improving Precision: 1. By repeated sampling and recutting of the die casting tool, along with production capability studies, even closer dimensions can be held—at additional sampling or other costs. 2. The die casting process may cause variations to occur in parting line separation. Thus, tolerances for dimensions that fall across the parting line on any given part should be checked in multiple locations, i.e., at four corners and on the center line. 3. In the case of extremely small zinc parts, weighing fractions of an ounce, special die casting machines can achieve significantly tighter toler- ances, with zero draft and flash-free operation. See section 4B Miniature Die Casting. NADCA Product Specification Standards for Die Castings / 2009
  • 15. 4A-15NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning 4A Angularity Tolerances (Plane surfaces): Standard Precision Tolerances Example: For Standard Tolerances — Surface -B- is formed by a moving die member in the same die section as datum plane -A-. If surface -B- is 5” (127 mm) long it will be perpendicular to the datum plane -A- within .011 (.28 mm). [.008 (.20 mm) for the first 3” (76.2 mm) and .003 (.08 mm) for the additional length.] Example: For Precision Tolerances — Surface -B- and the datum plane -A- are formed in opposite die sec- tions. If surface -B- is 7” (177.8 mm) long it will be parallel to the datum plane -A- within .009 (.23 mm). [.005(.13 mm) for the first 3” (76.2 mm) and .004 (.10 mm) for the additional length.] Type Surfaces 3” (76.2 mm) or less Each 1” (25.4 mm) over 3” (76.2 mm) Standard .008 (.20 mm) .0015 (.038 mm) Precision .005 (.13 mm) .001 (.025 mm) DATUM A SURFACE B Standard Tol. Precision Tol. MDC Angularity Tolerance Same Die Half 0 0.005 0.01 0.015 0.02 0.025 3 (76.2) 4 (101.6) 5 (127.0) 6 (152.4) 7 (177.8) 8 (203.2) 9 (228.6) 10 (254.0) 11 (279.4) 12 (304.8) Linear Surface in Inches (mm) ToleranceinInches NADCA S/P-4A-4-09 STANDARD /PRECISION TOLERANCES Standard Tolerances shown represent normal die casting production practice at the most economical level. Precision Tolerance values shown represent greater casting accuracy involving extra precision in die construction and/or special control in production. They should be specified only when and where necessary, since additional costs may be involved. NADCA Product Specification Standards for Die Castings / 2009
  • 16. 4A-16 NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning Angularity Tolerances (Plane surfaces): Standard Precision Tolerances Example: For Standard Tolerances — Surface -B- is formed by a moving die member and the datum plane -A- is formed by the opposite die section. If surface -B- is 5” (127 mm) long it will be perpendicular to the datum plane -A- within .017 (.43 mm). [.011 (.28 mm) for the first 3” (76.2 mm) and .006 (.15 mm) for the additional length.] Surfaces -B- and -C- are formed by two moving die members. If surface -B- is used as the datum plane and surface -B- is 5” (127 mm) long, surface -C- will be parallel to surface -B- within .017 (.43 mm). [.011 (.28 mm) for the first 3” (76.2 mm) and .006 (.15 mm) for the additional length.] Example: For Precision Tolerances — Surface -B- is formed by a moving die member and the datum plane -A- is formed by the opposite die section. If surface -B- is 5” (127 mm) long it will be perpendicular to the datum plane -A- within .012 (.30 mm). [.008 (.20 mm) for the first 3” (76.2 mm) and .004 (.10 mm) for the additional length.] Surfaces -B- and -C- are formed by two moving die members. If surface -B- is used as the datum plane and surface -B- is 5” (127 mm) long, surface -C- will be parallel to surface -B- within .012 (.30 mm). [.008 (.20 mm) for the first 3” (76.2 mm) and .004 (.10 mm) for the additional length.] Type Surfaces 3” (76.2 mm) or less Each 1” (25.4 mm) over 3” (76.2 mm) Standard .011 (.28 mm) .003 (.076 mm) Precision .008 (.20 mm) .002 (.05 mm) DATUM A SURFACE B SURFACE C Standard Tol. Precision Tol. MDC Angularity Tolerance Across Parting Line 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 3 (76.2) 4 (101.6) 5 (127.0) 6 (152.4) 7 (177.8) 8 (203.2) 9 (228.6) 10 (254.0) 11 (279.4) 12 (304.8) Linear Surface in Inches (mm) ToleranceinInches NADCA S/P-4A-4-09 STANDARD /PRECISION TOLERANCES Standard Tolerances shown represent normal die casting production practice at the most economical level. Precision Tolerance values shown represent greater casting accuracy involving extra precision in die construction and/or special control in production. They should be specified only when and where necessary, since additional costs may be involved. NADCA Product Specification Standards for Die Castings / 2009
  • 17. 4A-17NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning 4A 10 Concentricity Tolerances: Varying Degrees of Standard Tolerance The concentricity of cylindrical surfaces is affected by the design of the die casting. Factors, such as casting size, wall thickness, shape, and complexity each have an effect on the concentricity of the measured surface. The tolerances shown below best apply to castings that are designed with uniformity of shape and wall thickness. It should be noted that concentricity does not necessarily denote circularity (roundness). Part fea- tures can be considered concentric and still demonstrate an out of roundness condition. See section 5.11, Runout vs. Concentricity, in Geometric Dimensioning Tolerancing for further explanation. Concentricity Tolerance is added to other tolerances to determine maximum tolerance for the feature. For example, a concentric part that may cross the parting line, the tolerance would be the Concentricity Tolerance added to Parting Line Tolerance to give overall part tolerance. Note that the tolerances in the table apply to a single casting regardless of the number of cavities. One Die Section Concentricity Tolerance in a fixed relationship in one die section is calculated by selecting the largest feature diameter, (Diameter A ) and calculating the tolerance from Table S-4A-5A using the chosen diameter. See information in the side column regarding selecting diameters for oval features. Selected diameter directly impacts degree of precision. Example: Tolerance in One Die Section — An oval feature has a minimum diameter of 7 inches and a maximum diameter of 8 inches identified by the largest oval in the drawing below. This feature must fit into a hole with a high degree of precision. The minimum diameter (Diameter A) is chosen to give the highest degree of precision. From Table S-4A-5A, the basic tolerance for the first 3 inches is 0.008 inches (0.20 mm). 0.002 inches (0.05 mm) is added for each of the additional 4 inches to yield a total Concentric- ity Tolerance of +0.016 inches (+0.40 mm) for the 7” diameter. T able S- 4A- 5 Co ncen tricit y T oler ances A B PL Surfaces in Fixed Relationship in One Die Section Basic Tolerance up to 3” (76.2mm) Diameter of Largest Diameter (A) Tolerance (T.I.R.) inches (mm) .008 (.20 mm) Additional Tolerance for each additional inch (25.4 mm) over 3”(76.2mm) +.002 (.05 mm) Surfaces formed by Opposite Halves of Die (single cavity) Largest Diameter A Fixed Concentricity Same Die Half 0 0.005 0.01 0.015 0.02 0.025 0.03 3 (76.2) 4 (101.6) 5 (127.0) 6 (152.4) 7 (177.8) 8 (203.2) 9 (228.6) 10 (254.0) 11 (279.4) 12 (304.8) Largest Diameter in Inches (mm) ToleranceinInches Table S-4A-5A: Concentricity Tolerance - Same Die Half (Add to other tolerances) NADCA S-4A-5-09 STANDARD TOLERANCES Concentricity is defined as a feature having a common center and is usually round, circular or oval. Half the diameter is the center of the feature. Standard and Precision Tolerance are not specified for Concentricity Tolerance since tolerance is determined from diameter. As noted in the Concentric- ity Tolerance description, concentricity does not denote roundness. The feature may be oval and still be concentric. Therefore tolerance precision may be variable depending where diameter is measured. If minimum diameter is chosen, the calculated tolerance from the table will be less indicating a higher degree of precision. If maximum diameter is chosen, then calculated toler- ance will be more indicating a more “standard” degree of precision. Diameters chosen between minimum and maximum will determine varying degrees of precision. A B NADCA Product Specification Standards for Die Castings / 2009
  • 18. 4A-18 NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning Concentricity Tolerances: Varying Degrees of Standard Tolerance Opposite Die Halves When concentric features are in opposite die halves, the area of the cavity at the parting line determines Concentricity Tolerance. If two concentric features meet at the parting line, it is the area of the larger feature that determines Concentricity Tolerance from table S-4A-5B. See the side column for determining the area of a concentric feature. As noted in the side column, degree of precision is determined from the calculated area when crossing the parting line. If there is a cavity at the parting line between concentric features that are located in opposite die halves such as area C on the figure below, area of the cavity determines Concentricity Toler- ance from table S-4A-5B. Total part tolerance is the combination of Concentricity Tolerance plus other feature tolerances for the part. Example: Tolerance in One Die Section — An oval feature has a minimum diameter of 6 inches and a maxi- mum diameter of 8 inches identified as Diameter A. Diameter B is 5 inches. However, the area of cavity C is 9 by 9 inches. If concentric features meet at the parting line through the squared area C, Concentricity Tolerance is determined from table S-4A-5B by the 9 by 9 area which is 81 inches square. From table S-4A- 5B the Concentricity Tolerance is +.012 inches (+.30 mm). If concentric features meet at the parting line directly, the area of the larger oval is used to determine the Concentricity Tolerance from table S-4A-5B. For example, if the minimum diameter is 6 inches and the maximum diameter is 8 inches, the average diameter is 7 inches. Using the Concentricity Area Calculation formula in the side column, the area is determined to be 38.5 inches square therefore the Concentricity Tolerance is +.008 inches (+.20 mm). T able S- 4A- 5 Co n cen tricit y T oler an ces Up to 50 in 2 (323 cm 2 ) + .008 (.20 mm) 51 in 2 to 100 in 2 (329 cm 2 to 645 cm 2 ) + .012 (.30 mm) 101 in 2 to 200 in 2 (652 cm 2 to 1290 cm 2 ) + .016 (.41 mm) 201 in 2 to 300 in 2 (1297 cm 2 to 1936 cm 2 ) + .022 (.56 mm) A B PL A B LP C Surfaces in Fixed Relationship in One Die Section Basic Tolerance up to 3” (76.2mm) Diameter of Largest Diameter (A) Tolerance (T.I.R.) inches (mm) .008 (.20 mm) Additional Tolerance for each additional inch (25.4 mm) over 3”(76.2mm) +.002 (.05 mm) Surfaces formed by Opposite Halves of Die (single cavity) Projected Area (C) of casting Additional Tolerance inches (mm) Conc. Tol. Across PL Concentricity Tolerance In Opposite Die Halves 0 0.005 0.01 0.015 0.02 0.025 50 (323) 100 (645) 200 (1290) 300 (1936) Projected Area in Inches Square (cm sq) ToleranceinInches 9Inches 9 Inches A B C - Die Cavity Table S-4A-5B: Concentricity Tolerance - Opposite Die Halves (Add to other tolerances) NADCA S-4A-5-09 STANDARD TOLERANCES Concentricity is defined as a feature having a common center and is usually round, circular or oval. Half the diameter is the center of the feature. Standard and Precision Tolerance are not specified for Concentricity Tolerance since tolerance is determined from calculated area. As noted in the Concentric- ity Tolerance description, concentricity does not denote roundness. The feature may be oval and still be concen- tric. Concentricity Tolerance precision is determined from chosen area and how the area is calculated. Concentric Area Calculation Round Features are those with equal diameter (D) regardless of where measured. Their area is calculated by: (3.14) x [(1/2 D) 2 ] Oval Feature areas are determined by averaging the minimum and maximum diameters and then using the same formula as that for Round Features. NADCA Product Specification Standards for Die Castings / 2009
  • 19. 4A-19NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning 4A Parting Line Shift: Standard Tolerance Parting line shift or die shift is a dimensional variation resulting from mismatch between the two die halves. The shift is a left/right type relationship that can occur in any direction parallel to the parting line of the two die halves. It has consequences to dimensions unlike parting line separation and moving die component tolerances. Parting line shift will influence dimensions that are measured across the parting line including concentricity of features formed by opposite die halves, and datum structures with datums in opposite die halves. Parting line shift compounds the affects of other tolerances measured across the parting line plane. Parting line shift can cause a part not to meet the requirements of form, fit and function. Dies are designed and built with alignment systems to minimize parting line shift. However, effectiveness of alignment systems in minimizing parting line shift will depend on temperature variations, die construction, type of die and wear. Variations in temperature between the two die halves of the die occur during the die’s run. With die steel changing size with temperature variation, the two die halves will change size with respect to each other. To accommodate these changes in size, the alignment systems are designed with clearance to eliminate binding during opening and closing of the die. This clearance is necessary for the operation of the die but will allow a certain amount of parting line shift. One side of the die may be heated or cooled to compensate for temperature variation between die halves. One method to compensate for temperature variation is in the design and gating of the die. Another method is to apply additional die lube between shots to cool the hotter die half. Minimizing temperature variation between die halves allows for a more precise alignment system which will limit temperature induced parting line shift. Moveable components (slides) within a die can also lead to parting line shift. Mechanical locks used to hold the slide in place during the injection of the metal can introduce a force that induces a parting line shift in the direction of the pull of the slide. The type of die will also affect parting line shift. Due to their design for inter-changeability, unit dies will inherently experience greater parting line shift than full size dies. If parting line shift is deemed critical during part design, a full size die should be considered rather than a unit die. Steps can be taken during the part design stage to minimize the impact of parting line shift. Datum structures should be set with all of the datum features in one half of the die. If this is not possible, additional tolerance may need to be added (see Geometric Dimensioning, Section 5). Another consideration during part design is to adjust parting lines so those features where mismatch is critical are cast in one half of the die. Steps can also be taken during the die design to minimize parting line shift. Interlocks and guide blocks can be added to dies to improve alignment, but result in a higher maintenance tool. Placement of the cavities in the die can also be used to minimize the effect of mismatch between the two die halves. Die wear and alignment system wear may impact parting line shift. As components wear, there is increasing lateral movement that will directly impact parting line shift. The method for decreas- ing wear induced parting line shift is to minimal moving parts when designing a die system, provide good cooling and lubrication, and have a good preventive maintenance program. It is important to note that parting line shift can occur at any time and its tolerance conse- quences should be discussed with the die caster at the design stage to minimize its impact on the final die casting. There are two components to calculate the affect of parting line shift on a part. The first component is to determine Parting Line Shift Projected Area Tolerance. Cavity area at the parting line is used to determine Projected Area Tolerance from table S-4A-6. The second component is to determine Linear Tolerance. Linear Tolerance is obtained from table S/P-4A-1 which was discussed earlier in this section. Parting Line Shift Projected Area Tolerance is added to the Linear Tolerance to obtain the volumetric affect of total Parting Line Shift Tolerance on the part. Parting Line Shift Tolerance is added to other feature tolerances to determine overall part tolerance. Note that the tolerances in the table apply to a single casting regardless of the number of cavities. NADCA S-4A-6-09 STANDARD TOLERANCES Parting Line Shift Tolerances are specified as standard tolerances, only. If a higher degree of precision is required, the caster should be consulted for possible steps that can be taken. Parting Line Shift Tolerance is only specified in Standard Tolerance because this is the lowest limit to meet the requirements of form, fit and function at the most eco- nomical value. Parting line variation has a compounding affect on feature tolerances across the parting line. NADCA Product Specification Standards for Die Castings / 2009
  • 20. 4A-20 NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning Parting Line Shift: Standard Tolerance Example: Parting Line Shift Tolerance The cavity area at the parting line is 75 inches squared. From Table S-4A-6, the Projected Area Parting Line Shift Tolerance is ± 0.006 (±0,152 mm). This is added to the Linear Tolerance from table S/P-4A-1. NADCA S-4A-6-09 STANDARD TOLERANCES PL Shift Tolerance Parting Line Shift Tolerance 0 0.005 0.01 0.015 0.02 0.025 0.03 50 (322.6) 100 (645.2) 200 (1290.3) 300 (1935.5) 500 (3225.8) 800 (5161.3) 1200 (7741.9) Projected Area in Inches Square (cm sq) ToleranceinInches Table SP-4-6 Parting Line Shift Tolerance (excluding unit dies) Projected Area of Die Casting inches 2 (cm 2 ) up to 50 in 2 (322.6 cm 2 ) 51 in2 to 100 in 2 (329.0 cm 2 to 645.2 cm 2 ) 101 in2 to 200 in 2 (651.6 cm 2 to 1290.3 cm 2 ) 201 in2 to 300 in 2 (1296.8 cm 2 to 1935.5 cm 2 ) 301 in2 to 500 in 2 (1941.9 cm 2 to 3225.8 cm 2 ) 501 in2 to 800 in 2 (3232.3 cm 2 to 5161.3 cm 2 ) 801 in2 to 1200 in 2 (5167.7 cm 2 to 7741.9 cm 2 ) Additional Tolerance inches (mm) ±.004 (±.102 mm) ±.006 (±.152 mm) ±.008 (±.203 mm) ±.011 (±.279 mm) ±.016 (±.406 mm) ±.020 (±.508 mm) ±.025 (±.635 mm) Table S-4A-6: Parting Line Shift Tolerance (Excluding unit dies) NADCA Product Specification Standards for Die Castings / 2009
  • 21. 4A-21NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning 4A Draft Requirements: Standard Tolerances Draft is the amount of taper or slope given to cores or other parts of the die cavity to permit easy ejection of the casting. All die cast surfaces which are normally perpendicular to the parting line of the die require draft (taper) for proper ejection of the casting from the die. This draft requirement, expressed as an angle, is not constant. It will vary with the type of wall or surface specified, the depth of the surface and the alloy selected. Draft values from the equations at right, using the illustration and the table below, provides Standard Draft Tolerances for draft on inside surfaces, outside surfaces and holes, achievable under normal production conditions. Draft Example (Standard Tolerances): In the case of an inside surface for an aluminum cast part, for which the constant “C” is 30 (6 mm), the recommended Standard Draft at three depths is: To achieve lesser draft than normal production allows, Precision Tolerances maybe specified (see opposite page). Calculation for Draft Distance Calculation for Draft Angle D = L C A = L D 0.01746 or Where: D= Draft in inches L= Depth or height of feature from the parting line C= Constant, from table S-4A-7, is based on the type of feature and the die casting alloy A= Draft angle in degrees Draft P D D A B L L L L P L NADCA S-4A-7-09 STANDARD TOLERANCES The formula for draft shown here represents Standard Tolerance, or normal casting production practice at the most economical level. For Precision Tolerance for draft, see the facing page. Note: As the formula indicates, draft, expressed as an angle, decreases as the depth of the feature increases. Twice as much draft is recommended for inside walls or surfaces as for outside walls/surfaces. This provision is required because as the alloy solidifies it shrinks onto the die features that form inside surfaces (usually located in the ejector half) and away from features that form outside surfaces (usually located in the cover half). Note also that the resulting draft calculation does not apply to cast lettering, logotypes or engraving. Such ele- ments must be examined individually as to style, size and depth desired. Draft requirements need to be discussed with the die caster prior to die design for satisfactory results. Drawing defines draft dimensions for interior and exterior surfaces and total draft for holes (draft is exaggerated for illustration). NADCA Product Specification Standards for Die Castings / 2009 57.2738———————— C √L Depth Draft Distance Draft Angle in. (mm) in. (mm) Degrees 0.1 (2.50) 0.010 (0.250) 6° 1.0 (25) 0.033 (0.840) 1.9° 5.0 (127) 0.075 (1.890) 0.85° (Used automatic equasion solve on “advanced solve page” at: http://www.quickmath.com/www.2/pages/modules/equations)
  • 22. 4A-22 NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning Draft Requirements: Standard Tolerances It is not common practice to specify draft separately for each feature. Draft is normally specified by a general note with exceptions called out for individual features. The formula should be used to establish general draft requirements with any exceptions identified. For example, the results at the left indicate that an aluminum casting with most features at least 1.0 in. deep can be covered with a general note indicating 2° minimum draft on inside surfaces and 1° minimum on outside surfaces (based on outside surfaces requiring half as much draft). Values of Constant C by Features and Depth (Standard Tolerances) Alloy Zinc/ZA Aluminum Magnesium Copper Inside Wall For Dim. in inches (mm) 50 (9.90 mm) 30 (6.00 mm) 35 (7.00 mm) 25 (4.90 mm) Outside Wall For Dim. in inches (mm) 100 (19.80 mm) 60 (12.00 mm) 70 (14.00 mm) 50 (9.90 mm) Hole, Total Draft for Dim. in inches (mm) 34 (6.75 mm) 20 (4.68 mm) 24 (4.76 mm) 17 (3.33 mm) Table S-4A-7: Draft Constants for Calculating Draft and Draft Angle NADCA S-4A-7-09 STANDARD TOLERANCES NADCA Product Specification Standards for Die Castings / 2009
  • 23. 4A-23NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning 4A Draft Requirements: Precision Tolerances All cast surfaces normally perpendicular to the parting line of the die require draft (taper) for proper ejection of the casting from the die. Minimum precision draft for inside walls is generally recommended at 3/4 degrees per side; with outside walls requiring half as much draft. Draft values from the equation at right, using the illustration and the table below, estimate specific Precision Draft Tolerances for draft on inside surfaces, outside surfaces and holes. Precision Draft Tolerances will vary with the type of wall or surface specified, the depth of the wall, and the alloy selected. Draft Example (Precision Tolerances): In the case of an inside surface for an aluminum cast part, for which the constant “C” is 40 (7.80 mm), the recommended Precision Draft at three depths is: To achieve lesser draft than normal production allows, Precision Tolerances maybe specified (see opposite page). Calculation for Draft Distance Calculation for Draft Angle D = L x 0.8 C A = L D 0.01746 or Where: D= Draft in inches L= Depth or height of feature from the parting line C= Constant, from table S-4A-7, is based on the type of feature and the die casting alloy A= Draft angle in degrees Draft P D D A B L L L L P L Drawing defines draft dimensions for interior and exterior surfaces and total draft for holes (draft is exaggerated for illustration). NADCA P-4A-7-09 PRECISION TOLERANCES Precision Tolerances for draft resulting from the calculations outlined here involve extra precision in die construction and/or special control in production. They should be specified only when necessary. Draft or the lack of draft can greatly affect castability. Early die caster consultation will aid in designing for minimum draft, yet sufficient draft for castability. Note: As the formula indicates, draft, expressed as an angle, decreases as the depth of the feature increases. See graphical representation on the following pages for various alloys. Twice as much draft is recommended for inside walls or surfaces as for outside walls/surfaces. This provision is required because as the alloy solidifies it shrinks onto the die features that form inside surfaces (usually located in the ejector half) and away from features that form outside surfaces (usually located in the cover half). Note also that the resulting draft calculation does not apply to die cast lettering, logotypes or engraving. Such elements must be examined individually as to style, size and depth desired. Draft requirements need to be discussed with the die caster prior to die design for satisfactory results. NADCA Product Specification Standards for Die Castings / 2009 45.819———————— C √L Depth Draft Distance Draft Angle in. (mm) in. (mm) Degrees 0.1 (2.50) 0.006 (0.150) 3.6° 1.0 (25) 0.020 (0.510) 1.1° 2.5 (63.50) 0.032 (1.140) 0.72° (Used automatic equasion solve on “advanced solve page” at: http://www.quickmath.com/www.2/pages/modules/equations)
  • 24. 4A-24 NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning Draft Requirements: Precision Tolerances It is not common practice to specify draft separately for each feature. Draft is normally speci- fied by a general note with exceptions called out for individual features. The formula should be used to establish general draft requirements with any exceptions identified. For example, the results at the left indicate that an aluminum casting with most features at least 1.0 in. deep can be covered with a general note indicating 1° minimum draft on inside surfaces and 0.5° minimum on outside surfaces (based on outside surfaces requiring half as much draft). Values of Constant C by Features and Depth (Precision Tolerances) Alloy Zinc/ZA Al/Mg/Cu Inside Wall For Dim. in inches (mm) 60 (12.00 mm) 40 (7.80 mm) Outside Wall For Dim. in inches (mm) 120 (24.00 mm) 80 (15.60 mm) Hole, Total Draft For Dim. in inches (mm) 40 (7.80 mm) 28 (5.30 mm) Table P-4A-7: Draft Constants for Calculating Draft and Draft Angle NADCA P-4A-7-09 PRECISION TOLERANCES NADCA Product Specification Standards for Die Castings / 2009
  • 25. 4A-25NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning 4A NADCA S/P-4A-7-09 STANDARD/PRECISION TOLERANCES Standard Inside Wall Standard Outside Wall Precision Inside Wall Precision Outside Wall Standard Hole Precision Hole Aluminum Draft 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 1 (25.4) 2 (50.8) 3 (76.2) 4 (101.6) 5 (127.0) 6 (152.4) 7 (177.8) 8 (203.2) 9 (228.6)10 (254.0)11 (279.4)12 (304.8) Length from Parting Line in Inches (mm) DraftinInches Standard Inside Wall Standard Outside Wall Precision Inside Wall Precision Outside Wall Standard Hole Precision Hole Aluminum Draft Angle 0 0.5 1 1.5 2 2.5 3 3.5 1 (25.4) 2 (50.8) 3 (76.2) 4 (101.6) 5 (127.0) 6 (152.4) 7 (177.8) 8 (203.2) 9 (228.6)10 (254.0)11 (279.4)12 (304.8) Length from Parting Line in Inches (mm) DraftAngleinDegrees NADCA Product Specification Standards for Die Castings / 2009
  • 26. 4A-26 NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate DimensioningNADCA S/P-4A-7-09 STANDARD/PRECISION TOLERANCES Standard Inside Wall Standard Outside Wall Precision Inside Wall Precision Outside Wall Standard Hole Precision Hole Copper Draft 0 0.05 0.1 0.15 0.2 0.25 1 (25.4) 2 (50.8) 3 (76.2) 4 (101.6) 5 (127.0) 6 (152.4) 7 (177.8) 8 (203.2) 9 (228.6)10 (254.0)11 (279.4)12 (304.8) Length from Parting Line in Inches (mm) DraftinInches Standard Inside Wall Precision Inside Wall Precision Outside Wall Standard Hole Precision Hole Standard Outside Wall Copper Draft Angle 0 0.5 1 1.5 2 2.5 3 3.5 4 1 (25.4) 2 (50.8) 3 (76.2) 4 (101.6) 5 (127.0) 6 (152.4) 7 (177.8) 8 (203.2) 9 (228.6)10 (254.0)11 (279.4)12 (304.8) Length from Parting Line in Inches (mm) DraftAngleinDegrees NADCA Product Specification Standards for Die Castings / 2009
  • 27. 4A-27NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning 4A Standard Inside Wall Standard Outside Wall Precision Inside Wall Precision Outside Wall Standard Hole Precision Hole Magnesium Draft 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 1 (25.4) 2 (50.8) 3 (76.2) 4 (101.6) 5 (127.0) 6 (152.4) 7 (177.8) 8 (203.2) 9 (228.6)10 (254.0)11 (279.4)12 (304.8) Length from Parting Line in Inches (mm) DraftinInches Standard Inside Wall Standard Outside Wall Precision Inside Wall Precision Outside Wall Standard Hole Precision Hole Magnesium Draft Angle 0 0.5 1 1.5 2 2.5 3 1 (25.4) 2 (50.8) 3 (76.2) 4 (101.6) 5 (127.0) 6 (152.4) 7 (177.8) 8 (203.2) 9 (228.6)10 (254.0)11 (279.4)12 (304.8) Length from Parting Line in Inches (mm) DraftAngleinDegrees NADCA S/P-4A-7-09 STANDARD/PRECISION TOLERANCES NADCA Product Specification Standards for Die Castings / 2009
  • 28. 4A-28 NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning Standard Inside Wall Standard Outside Wall Precision Inside Wall Precision Outside Wall Standard Hole Precision Hole Zinc Draft 0 0.02 0.04 0.06 0.08 0.1 0.12 1 (25.4) 2 (50.8) 3 (76.2) 4 (101.6) 5 (127.0) 6 (152.4)7 (177.8) 8 (203.2) 9 (228.6)10 (254.0)11 (279.4)12 (304.8) Length from Parting Line in Inches (mm) DraftinInches Standard Inside Wall Standard Outside Wall Precision Inside Wall Precision Outside Wall Standard Hole Precision Hole Zinc Draft Angle 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 1 (25.4) 2 (50.8) 3 (76.2) 4 (101.6) 5 (127.0) 6 (152.4) 7 (177.8) 8 (203.2) 9 (228.6)10 (254.0)11 (279.4)12 (304.8) Length from Parting Line in Inches (mm) DraftAngleinDegrees NADCA S/P-4A-7-09 STANDARD/PRECISION TOLERANCES NADCA Product Specification Standards for Die Castings / 2009
  • 29. 4A-29NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning 4A Flatness Requirements: Standard Tolerance Flatness defines surface condition not part thickness. See the flatness explanation on the opposite page. Standard Tolerance is calculated using the largest dimensions defining the area where the toler- ance is to be applied. If flatness is to be determined for a circular surface such as the top of a can, the largest dimension is the diameter of the can. If flatness is to be determined for a rectangular area, the largest dimension is a diagonal. For greater accuracy, see Precision Tolerances for flatness on the opposite page. Example: Flatness Tolerance - Diagonal For a part where the diagonal measures 10 inches (254 mm), the maximum Flatness Standard Tolerance from table S-4A-8 is 0.008 inches (0.20 mm) for the first three inches (76.2 mm) plus 0.003 inches (0.08 mm) for each of the additional seven inches for a total Flatness Standard Tolerance of 0.029 inches (0.76 mm). Table S-4-8 Flatness Tolerances, As-Cast: All Alloys Maximum Dimension of Die Cast Surface up to 3.00 in. (76.20 mm) Additional tolerance, in. (25.4 mm) for each additional in. (25.4 mm) Tolerance inches (mm) 0.008 (0.20 mm) 0.003 (0.08 mm) Flatness Example Explanation NADCA S-4A-8-09 STANDARD TOLERANCES The flatness values shown here represent Standard Tolerances, or normal casting production practice at the most economical level. For greater casting accuracy see Precision Tolerances for this characteris- tic on the facing page. Flatness is described in detail in Section 5, Geometric Dimensioning Toleranc- ing. Simply put, Flatness Tolerance is the amount of allowable surface variation between two parallel planes which define the tolerance zone. See the figures below. Flatness of a continuous plane surface on a casting should be measured by a method mutually agreed upon by the designer, die caster and the customer before the start of die design. Note: The maximum linear dimension is the diameter of a circular surface or the diagonal of a rectangular surface. Flatness Design Guidelines: 1. All draft on walls, bosses and fins surrounding and underneath flat surfaces should be standard draft or greater. 2. Large bosses or cross sec- tions can cause sinks and shrinkage distortions and should be avoided directly beneath flat surfaces. 3. Changes in cross section should be gradual and well filleted to avoid stress and shrinkage distortions. 4. Symmetry is important to obtain flatness. Lobes, legs, bosses and variations in wall height can all affect flatness. Flatness Example Explanation NADCA Product Specification Standards for Die Castings / 2009
  • 30. 4A-30 NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning Flatness Requirements: Precision Tolerance The values shown for Precision Tolerance for flatness represent greater casting accuracy involving extra steps in die construction and additional controls in production. They should be specified only when and where necessary since additional costs may be involved. Even closer tolerances may be held by working with the die caster to identify critical zones of flatness. These areas may be amenable to special die construction to help maintain flatness. Flatness Explanation As noted in the explanation diagram, flatness is independent of all other tolerance features including thickness. Part thickness has a nominal thickness of 0.300 ±0.010. Flatness Tolerance is 0.005. Therefore at the high limit thickness the part surface flatness can be between 0.305 and 0.310 nominal thickness flatness can be between 0.300 and 0.305. Low limit thickness flatness can be between 0.290 and 0.295. Flatness can not range between 0.290 and 0.310. Using both high and low thickness in combination with flatness defeats the purpose for specifying flatness. Example: Flatness Tolerance - Diagonal For a part where the diagonal measures 10 inches (254 mm), the maximum Flatness Precision Tolerance from table P-4A-8 is 0.005 inches (0.13 mm) for the first three inches (76.2 mm) plus 0.002 inches (0.05 mm) for each of the additional seven inches for a total Flatness Standard Tolerance of 0.019 inches (0.48 mm). Standard Tolerance Zone Precision Tolerance Zone Flatness Tolerance 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 3 (76.2) 4 (101.6) 5 (127.0) 6 (152.4) 7 (177.8) 8 (203.2) 9 (228.6) 10 (254.0) 11 (279.4) 12 (304.8) Tolerance Zone in Inches (mm) Tolerancein+Inches Table P-4A-8 Flatness Tolerances, As-Cast: All Alloys Maximum Dimension of Die Cast Surface up to 3.00 in. (76.20 mm) Additional tolerance, in. (25.4 mm) for each additional in. (25.4 mm) Tolerance inches (mm) 0.005 (0.13 mm) 0.002 (0.05 mm) Explanation PART AT HIGH SIZE LIMIT PART AT NOMINAL SIZE PART AT LOW SIZE LIMIT .005 TOL ZONE.005 TOL ZONE.005 TOL ZONE .310 .300 .290 NADCA P-4A-8-09 PRECISION TOLERANCES Precision Tolerance values for flatness shown represent greater casting accuracy involving extra precision in die construction. They should be specified only when and where necessary since additional cost may be involved. Notes: The maximum linear dimension is the diameter of a circular surface or the diagonal of a rectangular surface. Flatness Design Guidelines: 1. All draft on walls, bosses and fins surrounding and underneath flat surfaces should be standard draft or greater. 2. Large bosses or cross sec- tions can cause sinks and shrinkage distortions and should be avoided directly beneath flat surfaces. 3. Changes in cross section should be gradual and well filleted to avoid stress and shrinkage distortions. 4. Symmetry is important to obtain flatness. Lobes, legs, bosses and variations in wall height can all affect flatness. NADCA Product Specification Standards for Die Castings / 2009
  • 31. 4A-31NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning 4A Design Recommendations: Cored Holes As-Cast Cored holes in die castings can be categorized according to their function. There are three major classifications. • Metal savers • Clearance holes • Function/locating holes Each of these functions implies a level of precision. Metal savers require the least precision; function/locating holes require the greatest precision. Leaving clearance holes in-between. Specifications for cored holes are the combination of form, size and location dimensions and tolerances required to define the hole or opening. Metal Savers Metal savers are cored features, round or irregular, blind or through the casting, whose primary purpose is to eliminate or minimize the use of raw material (metal/alloy). The design objective of the metal saver is to reduce material consumption, while maintaining uniform wall thickness, good metal flow characteristics, good die life characteristics with minimal tool maintenance. Design recommendation: 1. Wall thickness Design for uniform wall thickness around metal savers. Try to maintain wall thickness within ±10% of the most typical wall section. 2. Draft Use draft per NADCA S-4A-7 for inside walls. Keep walls as parallel as practical. 3. Radii/fillets Use as large a radius as possible, consistent with uniform wall thickness. Refer to NADCA guidelines G-6-2. Consider 0.06 inch radius (1.5 mm radius.) as a minimum. A generous radius at transitions and section changes will promote efficient metal flow during cavity filling. Clearance Holes Clearance holes are cored holes, round or irregular, blind or through the casting, whose primary purpose is to provide clearance for features and components. Clearance implies that location of the feature is important. Design recommendation: 1. Tolerance Dimensions locating the cored hole should be per NADCA Standard tolerances; S-4A-1 Linear Dimension, S-4A-2 Parting Line Dimensions and S-4A-3 Moving Die Components. 2. Wall thickness Design for uniform wall thickness around metal savers. Try to maintain wall thickness within ±10% of the most typical wall section. If hole is a through hole, allowance should be made for any trim edge per NADCA G-6-5, Commercial Trimming within 0.015 in. (0.4 mm). 3. Draft Use draft per NADCA S-4A-3 for inside walls. Keep walls as parallel as practical. 4. Radii/fillets Use as large a radius as possible, consistent with uniform wall thickness. Refer to NADCA guidelines G-6-2. Consider 0.06 inch radius (1.5 mm radius.) as a minimum. A generous radius at transitions and section changes will promote efficient metal flow during cavity filling. NADCA Product Specification Standards for Die Castings / 2009
  • 32. 4A-32 NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning For holes with less than a 0.25 inch diameter, wall stock should be a minimum of one half the hole diameter. For holes with larger than a 0.25 inch diameter, the wall stock shall be the nominal wall thickness (subject to part design). Functional/Locating Holes Functional/locating holes are cored holes whose purpose is to provide for a functional purpose such as threading, inserting and machining or location and alignment for mating parts or second- ary operations. Design recommendation: 1. Tolerance Dimensions locating the cored hole to be per NADCA Precision tolerances; P-4A-1 Linear Dimen- sion, P-4A-2 Parting Line Dimensions and P-4A-3 Moving Die Components. 2. Wall thickness Design for uniform wall thickness around metal savers. Try to maintain wall thickness within ±10% of the most typical wall section. If hole is a through hole, allowance should be made for any trim edge per NADCA G-6-5, Commercial Trimming within 0.015 inch (0.4 mm) or if this is not acceptable, a mutually agreed upon requirement. 3. Draft Use draft per NADCA P-4A-7 for inside walls. Keep walls as parallel as practical. 4. Radii/fillets Use as large a radius as possible, consistent with uniform wall thickness. Refer to NADCA guidelines G-6-2. Consider 0.03 inch radius (0.8 mm radius.) as a minimum. A generous radius at transitions and section changes will promote efficient metal flow during cavity filling. Other Design Considerations Hole depths Note: The depths shown are not applicable under conditions where small diameter cores are widely spaced and, by design, are subject to full shrinkage stress. Perpendicularity See Section 5 pages 5-19 and 5-20 Orientations Tolerances. Diameter of Hole — Inches 1/8 5/32 3/16 1/4 3/8 1/2 5/8 3/4 1 Alloy Maximum Depth — Inches Zinc* 3/8 9/16 3/4 1 1-1/2 2 3-1/8 4-1/2 6 Aluminum* 5/16 1/2 5/8 1 1-1/2 2 3-1/8 4-1/2 6 Magnesium* 5/16 1/2 5/8 1 1-1/2 2 3-1/8 4-1/2 6 Copper 1/2 1 1-1/4 2 2-1/2 5 NADCA Product Specification Standards for Die Castings / 2009
  • 33. 4A-33NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning 4A NADCA Product Specification Standards for Die Castings / 2009
  • 34. 4A-34 NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning Cored Holes for Cut Threads: Standard Tolerances Cored holes for cut threads are cast holes that require threads to be cut (tapped) into the metal. The table below provides the dimensional tolerances for diameter, depth and draft for each specified thread type (Unified and Metric Series). When required, cored holes in Al, Mg, Zn and ZA may be tapped without removing draft. This Standard Tolerance recommenda- tion is based on allowing 85% of full thread depth at the bottom D2 (small end) of the cored hole and 55% at the top D1 (large end) of the cored hole. A countersink or radius is also recommended at the top of the cored hole. This provides relief for any displaced material and can also serve to strengthen the core. Threads extend through the cored hole as by Y. X shows the actual hole depth. As with the countersink at the top of the hole, the extra hole length provides relief for displaced material and allows for full thread engagement. Tolerances below apply to all alloys. NADCA S-4A-9-09 STANDARD TOLERANCES The values shown represent Standard Tolerances, or normal casting production practice at the most economi- cal level. For greater casting accuracy see Precision Toler- ances for the characteristic on the facing page. Metric Hole Diameter Thread Depth Hole Depth Series D1, Max. D2 , Min. Y, Max. X, Max. Thread Size mm mm mm mm M3.5 X 0.6 3.168 2.923 7.88 9.68 M4 X 0.7 3.608 3.331 9.00 11.10 M5 X 0.8 4.549 4.239 11.25 13.65 M6 X 1 5.430 5.055 13.50 16.50 M8 X 1.25 7.281 6.825 18.00 21.75 f M8 X 1 7.430 7.055 14.00 17.00 M10 X 1.5 9.132 8.595 22.50 27.00 f M10 X 0.75 9.578 9.285 10.00 12.25 f M10 X 1.25 9.281 8.825 20.00 23.75 M12 X 1.75 10.983 10.365 27.00 32.25 f M12 X 1 11.430 11.055 15.00 18.00 f M12 X 1.25 11.281 10.825 18.00 21.75 M14 X 2 12.834 12.135 31.50 37.50 fM14 X 1.5 13.132 12.595 24.50 29.00 f M15 X 1 14.430 14.055 15.00 18.00 M16 X 2 14.834 14.135 32.00 38.00 f M16 X 1.5 15.132 14.595 24.00 28.50 f M17 X 1 16.430 16.055 15.30 18.30 f M18 X 1.5 17.132 16.595 24.30 28.80 M20 X 2.5 18.537 17.675 40.00 47.50 f M20 X 1 19.430 19.055 15.00 18.00 f M20 X 1.5 19.132 18.595 25.00 29.50 f M22 X 1.5 21.132 20.595 25.30 29.80 M24 X 3 22.239 21.215 48.00 57.00 f M24 X 2 22.834 22.135 30.00 36.00 f M25 X 1.5 24.132 23.595 25.00 29.50 f M27 X 2 25.834 25.135 33.75 39.75 M30 X 3.5 27.941 26.754 60.00 70.50 Table S-4A-9 Cored Holes for Cut Threads (Standard Tolerances) — Unified Series and Metric Series Unified Hole Diameter Thread Depth Hole Depth Series/ D1, Max. D2, Min. Y, Max. X, Max. Class inches inches inches inches 6-32, UNC/2B, 3B 0.120 0.108 0.414 0.508 6-40, UNF/2B 0.124 0.114 0.345 0.420 8-32, UNC/2B 0.146 0.134 0.492 0.586 8-36, UNF/2B 0.148 0.137 0.410 0.493 10-24, UNC/2B 0.166 0.151 0.570 0.695 10-32, UNF/2B 0.172 0.160 0.475 0.569 12-24, UNC/2B 0.192 0.177 0.648 0.773 12-28, UNF/2B 0.196 0.182 0.540 0.647 1/4A-20, UNC/1B, 2B 0.221 0.203 0.750 0.900 1/4A-28, UNF/1B, 2B 0.230 0.216 0.500 0.607 5/16-18, UNC/1B, 2B 0.280 0.260 0.781 0.948 5/16-24, UNF/1B, 2B 0.289 0.273 0.625 0.750 3/8-16, UNC/1B, 2B 0.339 0.316 0.938 1.125 3/8-24, UNF/1B, 2B 0.351 0.336 0.656 0.781 7/16-14, UNC/1B, 2B 0.396 0.371 1.094 1.308 7/16-20, UNF/1B, 2B 0.409 0.390 0.766 0.916 1/2-13, UNC/1B, 2B 0.455 0.428 1.250 1.481 1/2-20, UNF/1B, 2B 0.471 0.453 0.750 0.900 9/16-12, UNC/1B, 2B 0.514 0.485 1.406 1.656 9/16-18, UNF/1B, 2B 0.530 0.510 0.844 1.010 5/8-11, UNC/1B, 2B 0.572 0.540 1.563 1.835 5/8-18, UNF/1B, 2B 0.593 0.573 0.781 0.948 3/4A-10, UNC/1B, 2B 0.691 0.657 1.688 1.988 3/4A-16, UNF/1B, 2B 0.714 0.691 0.938 1.125 7/8- 9, UNC/1B, 2B 0.810 0.772 1.750 2.083 7/8-14, UNF/1B, 2B 0.833 0.808 1.094 1.308 1- 8, UNC/1B, 2B 0.927 0.884 2.000 2.375 1-12, UNF/1B. 2B 0.951 0.922 1.250 1.500 DD1 2 Y X Tip or Spherical Radius Optional Table S-4A-9: Cored Holes for Cut Threads (Standard Tolerances) – Unified Series and Metric Series f = Fine Pitch Series NADCA Product Specification Standards for Die Castings / 2009
  • 35. 4A-35NADCA Product Specification Standards for Die Castings / 2006 Engineering Design: Coordinate Dimensioning 4A Cored Holes for Cut Threads: Precision Tolerances Cored holes for cut threads are cast holes that require threads to be cut (tapped) into the metal. The table below provides the dimensional tolerances for diameter, depth and draft for each specified thread type (Unified and Metric Series). When required, cored holes in Al, Mg, Zn and ZA may be tapped without removing draft. This Precision Tolerance recommendation is based on allowing 95% of full thread depth at the bottom D2 (small end) of the cored hole and the maximum minor diameter at the top D1 (large end) of the cored hole. A countersink or radius is also recommended at the top of the cored hole. This provides relief for any displaced material and can also serve to strengthen the core. The Precision Tolerance values shown represent greater casting accuracy involving extra precision in die construction and/or special control in production. They should be specified only when and where necessary, since additional cost may be involved. Table P-4A-9: Cored Holes for Cut Threads (Precision Tolerances) – Unified Series and Metric Series Table P-4A-9 Cored Holes for Cut Threads (Precision Tolerances) — Unified Series and Metric Series Unified Hole Diameter Thread Depth Hole Depth Series/ D1, Max. D2, Min. Y, Max. X, Max. Class inches inches inches 0-80, UNF/2B, 3B (0.051) (0.047) (0.130) (0.163) 1-64, UNC/2B, 3B (0.062) (0.057) (0.200) (0.250) 1-72, UNF/2B, 3B (0.064) (0.059) (0.160) (0.200) 2-56, UNC/2B, 3B (0.074) (0.068) (0.240) (0.300) 2-64, UNF/2B, 3B (0.075) (0.070) (0.200) (0.250) 3-48, UNC/2B, 3B (0.085) (0.078) (0.280) (0.350) 3-56, UNF/2B, 3B (0.087) (0.081) (0.220) (0.275) 4A-40, UNC/2B, 3B (0.094) (0.086) (0.320) (0.400) 4A-48, UNF/2B, 3B (0.097) (0.091) (0.240) (0.300) 5-40, UNC/2B, 3B 0.106 0.099 0.280 0.350 5-44, UNF/2B, 3B 0.108 0.102 0.240 0.300 6-32, UNC/2B, 3B 0.114 0.106 0.350 0.438 6-40, UNF/2B 0.119 0.112 0.270 0.338 8-32, UNC/2B 0.139 0.132 0.290 0.363 8-36, UNF/2B 0.142 0.135 0.260 0.325 10-24, UNC/2B 0.156 0.147 0.390 0.488 10-32, UNF/2B 0.164 0.158 0.240 0.300 12-24, UNC/2B 0.181 0.173 0.340 0.425 12-28, UNF/2B 0.186 0.179 0.270 0.338 1/4A-20, UNC/1B, 2B 0.207 0.199 0.370 0.463 1/4A-28, UNF/1B, 2B 0.220 0.213 0.270 0.338 5/16-18, UNC/1B, 2B 0.265 0.255 0.440 0.550 5/16-24, UNF/1B, 2B 0.277 0.270 0.310 0.388 3/8-16, UNC/1B, 2B 0.321 0.311 0.470 0.588 3/8-24, UNF/1B, 2B 0.340 0.332 0.340 0.425 7/16-14, UNC/1B, 2B 0.376 0.364 0.570 0.713 7/16-20, UNF/1B, 2B 0.395 0.386 0.400 0.500 1/2-13, UNC/1B, 2B 0.434 0.421 0.640 0.800 1/2-20, UNF/1B, 2B 0.457 0.449 0.370 0.463 9/16-12, UNC/1B, 2B 0.490 0.477 1.280 1.600 9/16-18, UNF/1B, 2B 0.515 0.505 0.880 1.100 5/8-11, UNC/1B, 2B 0.546 0.532 1.430 1.788 5/8-18, UNF/1B, 2B 0.578 0.568 0.930 1.163 3/4A-10, UNC/1B, 2B 0.663 0.647 1.590 1.988 3/4A-16, UNF/1B, 2B 0.696 0.686 0.950 1.188 7/8- 9, UNC/1B, 2B 0.778 0.761 1.750 2.188 7/8-14, UNF/1B, 2B 0.814 0.802 1.200 1.500 1- 8, UNC/1B, 2B 0.890 0.871 1.900 2.375 1-12, UNF/1B. 2B 0.928 0.914 1.340 1.675 Metric Hole Diameter Thread Depth Hole Depth Series D1, Max. D2, Min. Y, Max. X, Max. Thread Size mm mm mm mm M1.6 X 0.35 (1.32) (1.24) (2.40) (3.45) M2 X 0.4 (1.68) (1.59) (3.00) (4.20) M2.5 X 0.45 (2.14) (2.04) (3.75) (5.10) M3 X 0.5 (2.60) (2.49) (4.50) (6.00) M3.5 X 0.6 2.99 2.88 5.25 7.05 M4 X 0.7 3.42 3.28 6.00 8.10 M5 X 0.8 4.33 4.17 7.50 9.90 M6 X 1 5.15 4.96 9.00 12.00 M8 X 1.25 6.91 6.70 12.00 15.75 f M8 X 1 7.15 6.96 12.00 15.00 M10 X 1.5 8.68 8.44 15.00 19.50 f M10 X 0.75 9.38 9.23 12.50 14.75 M10 X 1.25 8.91 8.70 15.00 18.75 M12 X 1.75 10.44 10.17 18.00 23.25 f M12 X 1 11.15 10.96 15.00 18.00 f M12 X 1.25 10.91 10.70 15.00 18.75 M14 X 2 12.21 11.91 21.00 27.00 f M14 X 1.5 12.68 12.44 21.00 25.50 f M15 X 1 14.15 13.96 18.75 21.75 M16 X 2 14.21 13.91 28.00 34.00 f M16 X 1.5 14.68 14.44 24.00 28.50 f M17 X 1 16.15 15.96 17.00 20.00 f M18 X 1.5 16.68 16.44 22.50 27.00 M20 X 2.5 17.74 17.38 30.00 37.50 f M20 X 1 19.15 18.96 20.00 23.00 f M20 X 1.5 18.68 18.44 20.00 24.50 f M22 X 1.5 20.68 20.44 22.00 26.50 M24 X 3 21.25 20.85 36.00 45.00 f M24 X 2 22.21 21.91 30.00 36.00 f M25 X 1.5 23.68 23.44 25.00 29.50 f M27 X 2 25.21 24.91 27.00 33.00 M30 X 3.5 26.71 26.31 37.50 48.00 DD1 2 Y X Tip or Spherical Radius Optional NADCA P-4A-9-09 PRECISION TOLERANCES Values in italics and parentheses are achievable but should be discussed with the die caster prior to finalization of a casting design. f = Fine Pitch Series NADCA Product Specification Standards for Die Castings / 2009

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