Die casting is an extremely versatile process. Molds, also known as dies, can be designed with almost infinitely complex shapes and geometries. Depending on the function of the casting it could be complete after ejection and trimming. Other castings require more processing after the gates, overflows, and vents have been trimmed.
Some features, such as internally tapped holes, cannot be die cast. Secondary machining procedures can be used to form these features.
Castings may require plating or painting also. When plating or painting is necessary on a casting it is important to maintain a smooth finish on the surface of the casting. Painting or plating will magnify any surface defects.
Secondary Processing Costs
Trimming
- Flash – Die castings are ejected from the dies with their gates, runners, overflows and metal extensions attached, which are called “flash.”
- Rough casting must incorporate features that will provide support in the trim die. Castings must also have sufficient strength and rigidity.
Machining
- Typically require few, if any, finish machining operations.
- Most commonly available die casting alloys are easier to machine than low carbon steel.
Impregnation
- Impregnation – Process in which an organic material is forced into the surface pores of a casting.
- Cost can be minimized by pressure testing all castings and impregnating only those that do not meet specifications.
Surface Finishing
- Variety of surface finishes can be applied to provide decorative effects, corrosion protection, or increased hardness and wear resistance.
- Costs are equivalent to those for alternative materials and processes.
