Die casting Tolerance

Linear Dimensions: Standard Tolerances

Note: Beczuse dies tuear over tbe course of producing casting,it should be noted that tbe mumber of sbots on a die prior to repair or replacement will belesfor tighter casting tolerances and greaterfor oider castin olerances.

Linear Dimensions: Precision Tolerances

Note:Because dies zwear over the course of producing castings,it should be noted that the number of sbots on a die prior to repair or replacement zoill be lessfor tighter casting tolerances and greater for wider casting tolerances.

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.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.

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.

Table S-4A-2 Parting Line Tolerances(Standard)-Added to Linear Tolerances
Projected Area of Die Casting inches²(cm²	Casting Alloys Tolerances shown are plus”values onb)
	Zinc	Aluminum	Magnesium	Copper
up to 10 jn² (64.5cm²)	+0.0045 (+0.114  mm)	+0.0055 (+0.14 mm)	+0.0055 (+0.14mm)	+0.008 (+0.20mm)
11in²to  20  in² 71.0  cm²to  129.0cm²)	+0.005 (+0.13mm)	+0.0065 (+0.165mm)	+0.0065 (+0.165mm)	+0.009 (+0.23mm)
21in²to   50in² (135.5cm²to    322.6cm²)	+0.006 (+0.15mm)	+0.0075 (+0.19mm)	+0.0075 (+0.19mm)	+0.010 (+0.25mm)
51in²to    100in² (329.0cm²to645.2cm²)	+0.009 (+0.23mm)	+0.012 (+0.30  mm)	+0.012 (+0.30mm)	一
101in²to    200in² (651.6cm²to  1290.3  cm²)	+0.012 (+0.30 mm)	+0.018 (+0.46mm)	+0.018 (+0.46mm)	一
201in²to  300  in² (1296.8  cm²to  1935.5cm²)	+0.018 (+0.46mm)	+0.024 (+0.61mm)	+0.024 (+0.61mm)	一

For projected area of die casting over 300in2(1935.5cm²), consult with your die coster.

NADCA Product Specification Standards for Die Castings/2012

Parting Line Shift: Standard Tolerance

Example: Parting Line Shift Tolerance

Table S-4A-6:Parting Line Shift Tolerance(Excluding unit dies)
Projected Area of Die Casting inches  ²(cm  ²)	Additional Tolerance inches(mm)
up to 50 in ²	±.004
(322.6cm  ²)	(±.102 mm)
51 in²to 100 in ²	±.006
(329.0cm²to  645.2  cm  ²)	(±.152 mm)
101  in²to  200  in²	±.008
(651.6cm²to 1290.3 cm 2)	(±.203 mm)
201 in²to 300 in ²	±.011
(1296.8cm²to  1935.5  cm  ²)	(±.279 mm)
301  in²to  500  in²	±.016
(1941.9cm²to 3225.8 cm 2)	(±.406mm)
501 in²to 800 in ²	±.020
(3232.3cm²to  5161.3  cm  ²)	(±.508mm)
801in²to  1200  in²	±.025
(5167.7 cm²to 7741.9 cm ²)	(±.635 mm)

Draft Requirements: 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:

Draft Requirements:Standard Tolerances

Table S-4A-7: Draft Constants for Calculating Draft and Draft Angle.

Values of Constant “C”by Features and Depth (Standard Tolerances)
Alloy	Inside Wall For  Dim.i inches  (mm)	Outside Wall For  Dim.in inches  (mm)	Hole,Total Draft for  Dim.in inches  (mm)
Zinc/ZA	50(9.90mm)	100(19.80 mm)	34(6.75mm)
Aluminum	30 (6.00 mm)	60(12.00 mm)	20(4.68 mm)
Magnesium	35 (7.00 mm)	70 (14.00 mm)	24(4.76 mm)
Copper	25(4.90 mm)	50 (9.90 mm)	17 (3.33 mm)

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 recommendation 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.

Table S-4A-9: Cored Holes for Cut Threads (Standard Tolerances) – Unified Series and Metric Series.

Unified Series/Class	Hole  Diameter D₁.Max.D2       ,Min. inches    inches		Thread Depth Y,Max. inches	Hole Depth X,Max. inches		Metric Series Thread	Hole Diameter		Thread Depth Y,Max. mm	Hole Depth XMax. mm
							D1,Max   mm	D2 Min.   mm
						Size A
6-32,UNC/2B,3B	0.120	0.108	0.414	0.508		M3.5X0.6	3.168	2.923	7.88	9.68
6-40,UNF/2B	0.124	0.114	0.345	0.420		M4X07	3.608	3.331	9.00	11.10
8-32,UNC/2B	0.146	0.134	0.492	0.586		M5X0.8	4.549	4.239	11.25	13.65
8-36,UNF/2B	0.148	0.137	0.410	0.493		M6X1	5.430	5.055	13.50	16.50
10-24 UNC/2B	0.166	0.151	0.570	0.695		M8X1.25	7.281	6.825	18.00	21.75
10-32,UNF/2B	0.172	0.160	0.475	0.569		FM8X1	7.430	7.055	14.00	17.00
12-24 UNC/2B	0.192	0.177	0.648	0.773		M10X1.5	9.132	8.595	22.50	27.00
12-28,UNF/2B	0.196	0.182	0.540	0.647		FM10X0.75	9.578	9.285	10.00	12.25
1/4A-20,UNC/1B,2B	0.221	0.203	0.750	0.900		fM10X1.25	9.281	8.825	20.00	23.75
1/4A-28,UNF/1B,2B	0.230	0.216	0.500	0.607		M12X175	10.983	10.365	27.00	32.25
5/16-18,UNC/1B,2B	0.280	0.260	0.781	0.948		fM12X1	11.430	11.055	15.00	18.00
5/16-24,UNF/1B,2B	0.289	0.273	0.625	0.750		FM12X1.25	11.281	10.825	18.00	21.75
3/8-16,UNC/1B,2B	0.339	0.316	0.938	1.125		M14X2	12.834	12.135	31.50	37.50
3/8-24,UNF/1B,2B	0.351	0.336	0.656	0.781		FM14X1.5	13.132	12.595	24.50	29.00
7/16-14,UNC/1B,2B	0.396	0.371	1.094	1.308			14.430	14.055	15.00	18.00
7/16-20,UNF/1B,2B	0.409	0.390	0.766	0.916		M16×2	14.834	14.135	32.00	38.00
1/2-13,UNC/1B,2B	0.455	0.428	1.250	1.481			15.132	14.595	24.00	28.50
1/2-20,UNF/1B,2B	0.471	0.453	0.750	0.900		FMI6×15	16.430	16.055	15.30	18.30
9/16-12,UNC/1B,2B	0.514	0.485	1.406	1.656		fM18X1.5	17.132	16.595	24.30	28.80
9/16-18,UNF/1B,2B	0.530	0.510	0.844	1.010		M20X2.5	18.537	17.675	40.00	47.50
5/8-11,UNC/1B,2B	0.572	0.540	1.563	1.835			19.430	19.055	15.00	18.00
5/8-18,UNF/1B,2B	0.593	0.573	0.781	0.948		FM20×15	19.132	18.595	25.00	29.50
3/4A-10,UNC/1B,2B	0.691	0.657	1.688	1.988		fM22X1.5	21.132	20.595	25.30	29.80
3/4A-16,UNF/1B,2B	0.714	0.691	0.938	1.125		M24X3	22.239	21.215	48.00	57.00
7/8-9,UNC/1B,2B	0.810	0.772	1.750	2.083		fM24X2	22.834	22.135	30.00	36.00
7/8-14,UNF/1B,2B	0.833	0.808	1.094	1.308		FM25X1.5	24.132	23.595	25.00	29.50
1-8,UNC/1B,2B	0.927	0.884	2.000	2.375		fM27×2	25.834	25.135	3375	39.75
1-12,UNF/1B.2B	0.951	0.922	1.250	1.500		M30X3.5	27.941	26.754	60.00	70.50

f= Fine Pitch Series

Additional Considerations for Large Castings

1 Fillet Radii:

1.1: Definition: Wall thickness is the distance between two parallel or nearly parallel surfaces. Wall thickness may vary depending on the application of draft. Wall thickness should be maintained as uniform as possible. A general guideline would be to keep the range of thickness within 2X of the thinnest wall. A second guideline is to keep the wall as thin as possible to meet the castings functional requirements.

1.2: General: 0.14” (3.5mm (+/- 0.5mm)1.2.1 Deviations: from the nominal condition are based upon product function and manufacturing process requirements.

2 Radii:

2.1 Fillet Radii: 2.1.1 General: 0.14” (+0.08/-0.04”) [3.5mm (+2.0mm/-1.0mm)]

2.1.1.1 Deviations: from the nominal condition are based upon product function and manufacturing process requirements.

2.1.2 Minimum: 0.060” (1.5mm)

2.2 Corner Radii:2.2.1 General: 0.060” (+0.08/-0.04”) [1.5mm (+2mm/-1mm)]

2.2.1.1 Deviations: from the nominal condition are based upon product function and manufacturing process requirements.

2.2.2 Minimum: 0.020” (0.5mm)

3 Cores:

3.1 Guidelines: Cores should be used to minimize machining stock, and should be pulled perpendicular to each other. Use stepped cores where possible to minimize finish stock, reduce heavy sections, and minimize porosity.

3.2 Minimum: Cored hole diameter to be 0.25” (6.0mm) in and parallel to the direction of die draw.

3.3 For holes Less Than: 0.50” (12.5mm) diameter the core hole length to diameter (L/D) ratio should not exceed 4:1.

3.4 For Holes Greater Than: 0.50” (12.5mm) diameter the core pin length to diameter (L/D) ratio should not exceed 10:1

Ejector Pin Bosses:

Surface Geometry:6.2.1: 0.06” (1.5mm) raised to 0.03” (0.8mm) depressed.

7 Trimming & Cleaning:

7.1 Parting Lines:

7.1.1 Trim Ribs-Gate and Parting Line: 0.12” maximum (1.5mm)

7.1.2 Gates & Overflows: 0-0.059” (0-1.5mm)

7.1.3 Flash: Asspecified in normal standard.

7.2 Cored Holes: 0-0.02” (0-0.5mm)

7.3 Openings:

7.3.1: 0-0.06” (0-1.5mm) at the finish machined face

7.3.2: 0-0.03”(0-0.8mm) on as-cast surfaces

7.3.3: 0-0.01” (0-2.5mm) of corner radii

7.4 Corners – Sharp: Not removed.

7.5 Ejector Pin Flash (Max. Projection):

7.5.1: 0-0.12” (0-3.0mm) on machined surfaces.

7.5.2: 0-0.04” (0-1.0mm) on as-cast surfaces.

7.6 Machined Surfaces: 0.12” (0-0.3mm) max.

7.7 Seam Lines: 0-0.02” (0-0.5mm)

7.8 Negative trim (shearing): condition is allowed when the nominal wall thickness is maintained.

Engineering & Design: Additional Specification Guidelines

Acceptable Ejector Pin Marks

Ejector pin marks on most die castings may be raised or depressed .015” (.381 mm). Raised ejector pin marks are preferred for optimum production. Larger castings may require additional ejector pin tolerances for proper casting ejection.

Ejector Pin Flash

Ejector pin marks are surrounded by a flash of metal. Normally, ejector pin flash will not be removed, unless it is objectionable to the end use of the part.Alternatively, ejector pin flash may be specified as crushed or flattened.In the case of either nonremoval or crushing/flattening, flash may flake off in use.Complete removal of ejector pin marks and flash by machining or hand scraping operations should be specified only when requirements justify the added expense.

With each die casting cycle, the die opens and the ejector plate in the ejector half of the die (Fig. A) automatically moves all ejector pins forward (Fig. B), releasing the casting from the die. Then, the die casting is removed from the die manually or mechanically.

5 Metal Extension (Flash) Removal

Guidelines to Extent of Removal

The table below provides a guide to the types of die casting metal extension (flash) which occurs in typical die castings and the amount of metal extension material which remains after (1) degating (removal of any gates and runners from the casting), and (2)commercial trimming of die casting metal extension.

Note that in some instances, where special surface finish characteristics are not involved, the most economic method of degating and metal extension (flash) removal may include a tumbling or vibratory deburring operation.

Guide to Nominal Metal Remaining by Type of Extension
Type of Metal Extension and Nominal Amount Remaining After Degating and Trimming
Operation Description	Thick  Gates  & Overflows >0.12”(3.0 mm)	Thin Gates &  Overflows  ≤0.12”(3.0 mm)	Parting Line and Seam Line Metal Extension	Metal Extension in Cored Holes	Sharp Corners
After Degating Nominal Flash Remaining	Rough   within 0.12”(3.0 mm)	Rough   within  0.12”(3.0 mm)	Excess Only Broken  Off	Not Removed	Not Removed
After Commercial Trimming* Nominal Extension Emaining	Within 0.06”(1.59mm)	Within  0.03”(0.8mm)	Within 0.015”(0.38 mm)	Removed within 0.010”(0.25 mm)	Not Removed
*“Commercially trimmed”does not include additional operations to remove loose material.For very beavy gates and overflowus,consultyour die caster.

Surface Finish, As-Cast

General Guidelines for As Cast Surface Finish on Die Cast Parts

The specification of external surface finish requirements is desirable for selected die casting applications and, in the case of some decorative parts, essential.The purpose of the guidelines presented here is to classify as-cast surface finish for die castings into a series of grades so that the type of as-cast finish required may be addressed and defined in advance of die design.These guidelines should be used for general type classification only, with final surface finish quality requirements specifically agreed upon between the die caster and the customer.The first four classes listed relate to cosmetic surfaces. Classfive relates to selected surface areas where specified surface finish limitations are required.

As-Cast Surface Finish Classifications and Final Finish or End Use
Class		As-Cast Finish	Final Finish or End Use
1	Utility Grade	No cosmetic requirements.Surface imperfections (cold shut,rubs,surface porosity,lubricant build-up,etc.)are acceptable	Used as-cast or with protective coatings;     Anodize(non-decorative)     Chromate(yellow,clear)
2	Functional   Grade	Surface imperfections(cold shut,rubs, surface porosity,etc.),that can be removed by spot polishing or can be covered by heavy paint,are acceptable.	Decorative Coatings:     Lacquers     Enamels     Plating(A1)     Chemical  Finish     Polished  Finish
3	Commercial   Grade	Slight surface imperfections that can be removed by agreed upon means are acceptable.	Structural Parts     (high stress areas) Plating(Zn) Electrostatic Painting Transparent Paints
4	Consumer   Grade	No objectionable surface imperfec- tions.Where surface waviness (flatness), noted by light reflection,is a reason for rejection special agreement should be reached with the die caster.	Special Decorative Parts
5	Superior   Grade	Surface finish,applicable to limited areas of the casting and dependent on alloy selected,to have a maximum value in micro inches as specified on print.	O-Ring Seats or Gasket Areas

7 Die Cast Lettering and Ornamentation

Lettering, medallions, logotypes, trademarks and a range of identification symbols may be reproduced on the surfaces of die cast parts.

Such as-cast ornamentation may be raised or depressed, but note that raised lettering will result in lower die construction costs and reduced die maintenance over the life of the die.Raised lettering on a depressed panel can be an economical substitute for depressed letters, as shown in the illustration below

Cast-in Lettering/Ornamentation Guidelines

In addition to the avoidance of depressed lettering or symbols in the casting surface,the following guidelines will achieve the most satisfactory results. The terms used refer to the illustrations below.

1. The Line Thickness (or “face”) of any letter to be clearly cast should be 0.010 in. (0.254 mm) or greater.

2. The Height (or raised dimension) of a cast letter or symbol should be equal to or less than the line thickness.

3. The Draft Angle should be greater than 10。.

4. Letters or symbols containing fine serifs or delicate lines cannot be expected to die cast cleanly.