Related Resources: mechanical-tolerances
Casting Tolerances per. NADCA and ISO
Manufacturing Processes | Mechanical Tolerances
The North American Die Casting Association (NADCA) has standard specifications for setting high pressure die casting tolerances. There is also the international ISO standard series, which focuses on casting tolerances. This series replaces the former ISO 8062:1994. ISO 8062:1994 did not have specifications to high pressure die castings.
ISO 8062-1…3 defines casting tolerances as DCT (Dimensional Casting Tolerance) grades and GCT (Geometrical Casting Tolerance) grades. The former ISO 8062 defined tolerances only as CT (Casting Tolerance) grades.
ISO 8062-1…3 consists of the following titles.
- ISO 8062-1:2007 Geometrical product specifications (GPS) Dimensional and geometrical tolerances for molded parts.
- ISO/TS 8062-2 Geometrical product specifications (GPS) Dimensional and geometrical tolerances for molded parts.
- ISO 8062-3:2007 Geometrical product specifications (GPS) Dimensional and geometrical tolerances for molded parts Part 3: General dimensional and geometrical tolerances and machining allowances for castings
Per the NADCA specifications, high pressure die casting tolerances are divided into two groups: normal and precision tolerances. International ISO standard does not use these terms, but specifies the tightest geometrical tolerance grade as one to be used only by "special agreement". The precision tolerances may be more costly to achieve, because the die caster has to pay more attention to the thermal stability during casting cycles and also the die has to be more rigid and well tested. Usually rigidity requires thicker plates and these add to the die costs.
NADCA specifications cover the following high pressure die casting tolerances:
- dimensional tolerance
- angular tolerance, which includes flatness, parallelism and perpendicularity tolerances
- concentricity tolerance
- parting line shift tolerance
- flatness tolerance
ISO 8062 covers the following tolerances:
- dimensional tolerances
- combined roundness, parallelism, perpendicularity and symmetry tolerance
- concentricity tolerance
- straightness tolerance − flatness tolerance
Dimensional tolerances cover tolerances for dimensions in one die half and dimensions over parting line. ISO 80623 standard asks to notice the dimensions over parting line, but does not give precise rules how.
NADCA dimensional tolerances, dimensions in one die halfStandard |
Aluminum |
Magnesium |
Zinc |
Copper |
Normal |
± 0,25 mm per 25 mm + additional ± 0,025 mm per each full 25 mm |
± 0,36 mm per 25 mm + additional ± 0,076 mm per each full 25 mm | ||
Precision |
± 0,05 mm per 25 mm + additional ± 0,025 mm per each full 25 mm |
± 0,18 mm per 25 mm + additional ± 0,05 mm per each full 25 mm | ||
ISO 80623:2007 dimensional tolerances
Largest overall dimension |
Aluminum |
Magnesium |
Zinc |
Copper |
≤ 50 mm |
DCTG 6: |
DCTG 3 – 6 |
DCTG 6 – 8 | |
> 50 mm ≤ 180 mm |
DCTG 7 | |||
> 180 mm ≤ 500 mm |
DCTG 8 | |||
> 500 mm |
DCTG 9 | |||
NADCA dimensional tolerances, dimension over parting line; normal (and precision) tolerances
Projected area of the casting |
Zinc |
Aluminum |
Magnesium |
Copper |
65cm2 |
+0,114 mm (+0,076) mm |
+0,14 mm (0,089) mm |
+0,14 mm (+0,089) mm |
+0,20 mm (+0,20) mm |
65 – 130 cm2 |
+0,13 mm (+0,089) mm |
+0,165 mm (+0,102) mm |
+0,165 mm (+0,102) mm |
+0,23 mm (+0,23) mm |
130 – 325 cm2 |
+0,15 mm (+0,102) mm |
+0,19 mm (+0,153) mm |
+0,19 mm (+0,153) mm |
+0,25 mm (+0,25) mm |
325 – 650 cm2 |
+0,23 mm (+0,153) mm |
+0,30 mm (+0,203) mm |
+0,30 mm (+0,203) mm |
- |
650 – 1300 cm2 |
+0,30 mm (+0,203) mm |
+0,46 mm (+0,305) mm |
+0,46 mm (+0,305) mm |
- |
1300 – 1950 cm2 |
+0,46 mm (+0,305) mm |
+0,61 mm (+0,406) mm |
+0,61 mm (+0,406) mm |
- |
NADCA dimensional tolerances, dimension towards a moving core; normal (and precision) tolerances
Projected area of the casting |
Zinc |
Aluminum |
Magnesium |
Copper |
65 cm2 |
+ 0,15 mm (+ 0,127) mm |
+ 0,20 mm (0,152) mm |
+ 0,20 mm (+ 0,127) mm |
+ 0,12 mm (+ 0,254) mm |
65 - 130 cm2 |
+ 0,23 mm (+ 0,178) mm |
+ 0,33 mm (+ 0,254) mm |
+ 0,33 mm (+ 0,178) mm |
- |
130 - 325 cm2 |
+ 0,33 mm (+ 0,254) mm |
+ 0,48 mm (+ 0,356) mm |
+ 0,48 mm (+ 0,254) mm |
- |
325 - 650 cm2 |
+ 0,48 mm (+ 0,356) mm |
+ 0,61 mm (+ 0,457) mm |
+ 0,61 mm (+ 0,356) mm |
- |
650 - 1300 cm2 |
+ 0,66 mm (+ 0,483) mm |
+ 0,81 mm (+ 0,61) mm |
+ 0,81 mm (+ 0,483) mm |
- |
1300 - 1950 cm2 |
+ 0,81 mm (+ 0,61) mm |
+ 0,1 mm (+ 0,762) mm |
+ 0,1 mm (+ 0,61) mm |
- |
Geometrical tolerances
Geometrical tolerances include straightness, flatness, combined roundness, parallelism, perpendicularity and symmetry tolerance, concentricity, parting line shift and flatness tolerance.
ISO 8062-3 straightness tolerance
Raw casting basic dimension (mm) |
Geometrical casting tolerance grade GCTG for straightness |
|||
From |
To |
2: Only by special agreement |
3: Common castings without back draft features with moving die components |
4: Complex castings and castings with moving die components |
— |
10 |
0,08 |
0,12 |
0,18 |
> 10 |
30 |
0,12 |
0,18 |
0,27 |
> 30 |
100 |
0,18 |
0,27 |
0,4 |
> 100 |
300 |
0,27 |
0,4 |
0,6 |
> 300 |
1000 |
0,4 |
0,6 |
0,9 |
Calculated for the largest dimension, for example diameter, measure from corner to corner in the case of rectangular objects, etc.
ISO 80623 and NADCA flatness tolerancesRaw casting basic dimension (mm) |
Geometrical casting tolerance grade GCTG for flatness |
NADCA casting tolerance for flatness |
|||
From |
To |
Only by special agreement |
Common castings without back draft features with moving die components |
Complex castings and castings with moving die components |
|
— |
10 |
0,12 |
0,18 |
0,27 |
At the first 75 mm 0,20 mm + 0,08 mm after each additional 25 mm |
> 10 |
30 |
0,18 |
0,27 |
0,4 | |
> 30 |
100 |
0,27 |
0,4 |
0,6 | |
> 100 |
300 |
0,4 |
0,6 |
0,9 | |
> 300 |
1000 |
0,6 |
0,9 |
1,4 | |
Tolerance mm
NADCA parting line shift tolerance
Projected area |
Tolerance |
< 325 cm2 |
± 0,102 mm |
325 650 cm2 |
± 0,152 mm |
650 1290 cm2 |
± 0,203 mm |
1290 1940 cm2 |
± 0,279 mm |
1940 3225 cm2 |
± 0,406 mm |
3225 5160 cm2 |
± 0,508 mm |
5160 7740 cm2 |
± 0,635 mm |
Raw casting basic dimension (mm) |
Only by special agreement |
Common castings without back draft features with moving die components |
Complex castings and castings with moving die components | |
| From | To | |||
— |
10 |
0,18 |
0,27 |
0,4 |
> 10 |
30 |
0,27 |
0,4 |
0,6 |
> 30 |
100 |
0,4 |
0,6 |
0,9 |
> 100 |
300 |
0,6 |
0,9 |
1,4 |
> 300 |
1000 |
0,9 |
1,4 |
2 |
Tolerance mm
Standard |
Both surfaces in the same die half |
Surfaces across the parting line or the other surface parting surface |
Both surfaces in the same die half, the other surface is a moving core surface |
Surfaces across the parting line or the other surface parting surface, tolerance towards a moving core surface |
Normal
|
0,13 mm per 75 mm + 0,025 mm per each additional 25 mm |
0,20 mm per 75 mm + 0,038 mm per each additional 25 mm |
0,20 mm per 75 mm + 0,038 mm per each additional 25 mm |
0,28 mm per 75 mm + 0,076 mm per each additional 25 mm |
Precision
|
0,08 mm per 75 mm + 0,025 mm per each additional 25 mm |
0,13 mm per 75 mm + 0,025 mm per each additional 25 mm |
0,13 mm per 75 mm + 0,025 mm per each additional 25 mm |
0,20 mm per 75 mm + 0,05 mm per each additional 25 mm |
Raw casting basic dimension (mm) |
2: Only by special agreement |
3: Common castings without back draft features with moving die components |
4: Complex castings and castings with moving die components | |
From |
To |
|||
— |
10 |
0,27 |
0,4 |
0,6 |
> 10 |
30 |
0,4 |
0,6 |
0,9 |
> 30 |
100 |
0,6 |
0,9 |
1,4 |
> 100 |
300 |
0,9 |
1,4 |
2 |
> 300 |
1000 |
1,4 |
2 |
3 |
Tolerance mm
NADCA concentricity tolerances
Projected area |
Both surfaces in the same die half |
Surfaces across the parting line, additional tolerance |
< 325 cm2 |
0,20 mm per 75 mm + 0,05 mm to each additional 25 mm
|
0,20 mm |
325 - 650 cm2 |
0,30 mm | |
650 - 1290 cm2 |
0,41 mm | |
1290 - 1940 cm2 |
0,56 mm |
ISO 8062:2007 Dimensional casting tolerance grades (DCTG)
The table presents the grades and dimension intervals, which are workable for high pressure die castings.
Raw casting basic dimension (mm) |
Dimensional casting tolerance grade DCTG |
||||||||||
From |
To |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
— |
10 |
±0,09 |
±0,13 |
±0,18 |
±0,26 |
±0,36 |
±0,52 |
±0,74 |
±1 |
±1,5 |
±2 |
10 |
16 |
±0,1 |
±0,14 |
±0,2 |
±0,28 |
±0,38 |
±0,54 |
±0,78 |
±1,1 |
±1,6 |
±2,2 |
16 |
25 |
±0,11 |
±0,15 |
±0,22 |
±0,3 |
±0,42 |
±0,58 |
±0,82 |
±1,2 |
±1,7 |
±2,4 |
25 |
40 |
±0,12 |
±0,17 |
±0,24 |
±0,32 |
±0,46 |
±0,64 |
±0,9 |
±1,3 |
±1,8 |
±2,6 |
40 |
63 |
±0,13 |
±0,18 |
±0,26 |
±0,36 |
±0,5 |
±0,7 |
±1 |
±1,4 |
±2 |
±2,8 |
63 |
100 |
±0,14 |
±0,2 |
±0,28 |
±0,4 |
±0,56 |
±0,78 |
±1,1 |
±1,6 |
±2,2 |
±3,2 |
100 |
160 |
±0,15 |
±0,22 |
±0,3 |
±0,44 |
±0,62 |
±0,88 |
±1,2 |
±1,8 |
±2,5 |
±3,6 |
160 |
250 |
— |
±0,24 |
±0,34 |
±0,5 |
±0,7 |
±1 |
±1,4 |
±2 |
±2,8 |
±4 |
250 |
400 |
— |
— |
±0,4 |
±0,56 |
±0,78 |
±1,1 |
±1,6 |
±2,2 |
±3,2 |
±4,4 |
400 |
630 |
— |
— |
— |
±0,64 |
±0,9 |
±1,2 |
±1,8 |
±2,6 |
±3,6 |
±5 |
630 |
1 000 |
— |
— |
— |
— |
±1 |
±1,4 |
±2 |
±2,8 |
±4 |
±6 |
1 000 |
1 600 |
— |
— |
— |
— |
— |
±1,6 |
±2,2 |
±3,2 |
±4,6 |
±7 |
Tolerance ± mm
ISO 8062:1994 Casting tolerance grades (CTG)
The tolerance grade is described with CT. It varies depending on the casting method and also on used material and alloy. Normal high pressure die casting tolerance grade is CT 57 for aluminum and magnesium, CT 68 for copper and CT 46 for zinc.
Raw casting basic dimension (mm) |
Casting tolerance grade CTG |
|||||||||||
From |
To |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
13 |
14 |
0 |
10 |
0,26 |
0,36 |
0,52 |
1,00 |
1,5 |
2,0 |
2,8 |
4,2 |
- |
- |
|
10 |
16 |
0,28 |
0,38 |
0,54 |
0,78 |
1,10 |
1,6 |
2,2 |
3,0 |
4,4 |
||
16 |
25 |
0,30 |
0,42 |
0,58 |
0,82 |
1,20 |
1,7 |
2,4 |
3,2 |
4,6 |
6,0 |
8,0 |
25 |
40 |
0,32 |
0,46 |
0,64 |
0,90 |
1,30 |
1,8 |
2,6 |
3,6 |
5,0 |
7,0 |
9,0 |
40 |
63 |
0,36 |
0,50 |
0,70 |
1,00 |
1,40 |
2,0 |
2,8 |
4,0 |
5,6 |
8,0 |
10,0 |
63 |
100 |
0,40 |
0,56 |
0,78 |
1,10 |
1,60 |
2,2 |
3,2 |
4,4 |
6,0 |
9,0 |
11,0 |
100 |
160 |
0,44 |
0,62 |
0,88 |
1,20 |
1,80 |
2,5 |
3,6 |
5,0 |
7,0 |
10,0 |
12,0 |
160 |
250 |
0,50 |
0,70 |
1,00 |
1,40 |
2,00 |
2,8 |
4,0 |
5,6 |
8,0 |
11,0 |
14,0 |
250 |
400 |
0,56 |
0,78 |
1,10 |
1,60 |
2,20 |
3,2 |
4,4 |
6,2 |
9,0 |
12,0 |
16,0 |
400 |
630 |
0,64 |
0,90 |
1,20 |
1,80 |
2,60 |
3,6 |
5,0 |
7,0 |
10,0 |
14,0 |
18,0 |
630 |
1000 |
1,00 |
- |
1,40 |
2,00 |
2,80 |
4,0 |
6,0 |
8,0 |
11,0 |
16,0 |
20,0 |
1000 |
1600 |
1,6 |
- |
- |
2,2 |
3,0 |
4,6 |
7,0 |
9,0 |
13,0 |
18,0 |
23,0 |
Tolerance ± mm
- J. Campbell, Castings, 2 nd edition, Elsevier, UK, 2005
- ISO 8062: 1994 Castings - System of dimensional tolerances and machining allowances
- EN ISO 80623:2007 Geometrical Product Specifications (GPS). Dimensional and geometrical tolerances for molded parts. Part 3: General dimensional and geometrical tolerances and machining allowances for castings
- Product Design for Die Casting, NADCA, USA 1998
- Product Specification Standards for Die Castings, NADCA, USA, 2006
Link to this Webpage:
© Copyright 2000 -
2024, by Engineers Edge, LLC
www.engineersedge.com
All rights reserved
Disclaimer |
Feedback
Advertising
| Contact
