There are several different considerations when choosing cast aluminum block alloys and options. The various physical, mechanical and chemical properties will all need to be considered in relation to how the aluminum component will be used.
For many types of applications, a cast aluminum block will be required because of the internal stability of the metal. This is also called dimensional stability, and it ensures that the aluminum will continue to be stable and have the strength, machinability and weldability that is required for a specific application.
Some types of cast aluminum will also have a higher Brinell hardness rating, which may be important for specific uses and applications. Often these harder types of cast aluminum will be required when the mold will have to go through additional machining. As some aluminum can become weaker when machined or welded, this may be an essential consideration.
Resistance to Heat and Corrosion
Alloys within specific series will have different levels or resistant to exposure to heat and corrosion. This allows the mold block to be carefully selected to meet the needs of the application.
Generally, aluminum has a good corrosion resistance level. However, some aluminum alloys, such as the 2000 series, tend to have a lower corrosion level than others. On the other end of the spectrum is the 5000 series, with 5083 alloy being particularly effective in high corrosion environments including in salt water marine applications.
Cost
One often misunderstood issues with cast aluminum block and mold suppliers is the difference in price and cost. Large volume aluminum fabricators are often able to obtain the best prices from mills. Buying directly from the fabricator rather than through a metal supplier often provides the best possible cost.
Very low costs with aluminum mold block may be a result of several different factors. The biggest is typically using recycled aluminum that is not monitored for quality assurance purposes. This can result in aluminum products that are not RoHS compliant or that contain high levels of contaminants or other items with the internal structure of the aluminum.
Invisible to the naked eye, these contaminants and other materials in the composition of the alloy can result in a loss in strength, higher corrosion rates and problems with maintaining the stability. This can impact machining, fabrication and working, all which result in added time, costs and frustration in production.
