What is a “lost wax” “investment casting”? What advantages do I have switching to this method?
Wax is injected into an aluminum tool to produce a pattern. This wax is a positive replica of the actual part increased by a calculated shrinkage of the wax and steel (approx 3%). For every casting one wax pattern must be made. The patterns are then assembled on a common “sprue” The assembly is commonly referred to as a “tree” of parts. The tree is repeatedly dipped into a ceramic slurry followed immediately with a refractory material (sand or stucco with excellent thermal properties). After a proper shell thickness is built, usually taking a week, the wax is removed (usually by autoclaving). The hollow shells are then preheated up to 2000 deg. F and molten metal is immediately poured into the hot shells. After cooling, the spent shell material now cracked and fractured is removed. Cleaning operations (cut off, grind, heat treat, straightening, blasting) takes place.
The goal is to supply near net shape parts often requiring little or no further machining or minimal operations. This process offers cost savings, design improvement, broad alloy selection including material interchangeability, close tolerances, and weight reduction. Once the initial tool is made you can start producing consistent parts order after order.