Pure aluminum is not suitable for most die castings. Aluminum is alloyed with a number of other metals to form a material that is very fluid at casting temperatures to promote die filling, resistance to soldering to avoid sticking in the mold and resistance to cracking during solidification. These are the alloys that we commonly cast:
360 is a good choice if corrosion resistance is an important consideration. Although a combination of chem-film and powder coating provide a great protection from corrosion, 360 will allow resistance on unpainted or scratched surfaces or when exposed to salt spray and other particularly corrosive environments. Unfortunately 360 is more difficult to cast which may result in poorer casting quality in difficult to fill areas. It also has poorer thermal conductivity than other alloys which makes it less desirable for high performance heat sinks.
380 is a very widely used alloy. It was once the overwhelming choice for all die castings. It has excellent resistance to soldering. We mostly use 380 alloy on parts whose specifications were drawn before the molds were transferred to our plant. Its die filling characteristics are not as good as the modified 384 alloy.
384 is our most popular alloy. We use it for electronic enclosures, heat sinks, hand tools, aircraft components and medical equipment. The improved filling characteristics improves overall cosmetics. This is particularly important where thin walls or more intricate details exist in the part design. It is slightly less corrosion resistant than 380.
413, once known as 13, is an alloy chosen for improved pressure tightness, corrosion resistance and especially for its thermal conductivity. Since all the die cast aluminum alloys have the same specific heat, it is the thermal conductivity which can improve the performance of heat sinks. Its primary disadvantage is decreased machinability and higher price.