One of the first steps in designing a die cast component is
choosing the proper alloy. Typical properties for the most commonly used alloys
are shown on the following charts.
| |
Aluminum |
Brass |
Magnesium |
Zinc |
| Tensile
strength, psi x 1000 |
47 |
55 |
34 |
41 |
| Yield
strength, psi x 100 (0.2 pct offset) |
23 |
30 |
23 |
— |
| Shear
strength, psi x 1000 |
28 |
37 |
20 |
31 |
| Fatigue
strength, psi x 1000 |
20 |
25 |
14 |
7 |
| Elongation,
pct in 2 in. |
3.50 |
15 |
3.0 |
10 |
| Hardness (Brinell) |
80 |
91 |
63 |
82 |
| Specific
gravity |
2.71 |
8.30 |
1.80 |
6.60 |
| Weight,
lb/cu. in. |
0.098 |
0.305 |
0.066 |
0.24 |
| Melting
point (liquid), °F |
1100 |
1670 |
1105 |
728 |
| Thermal
conductivity, CG5 |
0.23 |
0.21 |
0.16 |
0.27 |
| Thermal
expansion, in./in./°F x 106 |
12.1 |
12.0 |
15.0 |
15.2 |
Electrical
conductivity,
pct of copper standard |
27 |
20 |
10 |
27 |
| Modulus of
elasticity, psi x 106 |
10.3 |
15 |
6.5 |
— |
| Impact
strength (Charpy), ft/lb |
3.0 |
40 |
2.0 |
43.0 |
|
Characteristics of Die Casting Alloys |
| |
Aluminum |
Brass |
Magnesium |
Zinc |
| Dimensional
stability |
Good |
Excellent |
Excellent |
Good |
| Corrosion
resistance |
Good |
Excellent |
Fair |
Fair |
| Casting ease |
Good |
Fair |
Good |
Excellent |
| Part
complexity |
Good |
Fair |
Good |
Excellent |
| Dimensional
accuracy |
Good |
Fair |
Excellent |
Excellent |
| Die cost |
Medium |
High |
Medium |
Low |
| Machining
cost |
Low |
Medium |
Low |
Low |
| Finishing
cost |
Medium |
Low |
High |
Low |
|
Chart does not intend to compare metals. Its purpose is to
show the most advantageous characteristics of each specific metal. For
more specific information, refer to NADCA Product Standards for Die
Casting. |
|
Dimensional and Weight Limit |
| |
Aluminum |
Brass |
Magnesium |
Zinc |
| Maximum
weight, lb. |
70 |
10 |
44 |
75 |
| Minimum wall
thickness, large casting, in. |
0.080 |
0.090 |
0.100 |
0.035 |
| Minimum wall
thickness, small casting, inc. |
0.040 |
0.055 |
0.040 |
0.015 |
| Minimum
variation per in. of diameter or length from drawing dimensions over one
in. |
0.0015 |
0.009 |
0.0015 |
0.001 |
| Cast
threads, max. per in. external |
24 |
10 |
24 |
32 |
| Cored holes,
min. diameter in. |
0.080 |
0.250 |
0.080 |
0.050 |
|
Finishing: Decorative |
| |
Aluminum |
Brass |
Magnesium |
Zinc |
| Chrome
plating |
Fair |
Excellent |
Fair |
Excellent |
| Black chrome
plating |
Fair |
Excellent |
— |
Excellent |
| Colored
plating |
Fair |
— |
— |
Excellent |
| Mechanical -
polishing & buffing |
Excellent |
Excellent |
Excellent |
Excellent |
| Lacquers,
enamels, epoxies & acrylics |
Excellent |
Excellent |
Excellent |
Excellent |
| Anodizing |
Fair |
— |
— |
— |
For more specific information, refer to NADCA Product
Specification Standards for Die Castings.
