With a few exceptions, the modern stainless-steel propeller is created using the investment casting process, a metallurgical art that dates back more than 4,000 years. Also known as the lost wax process, ancient cultures used investment casting to create artwork and jewelry, usually carving a pattern from beeswax and investing, or covering, the wax pattern with a shell of clay. Molten copper, bronze or gold was then poured through a wax channel into the shell, displacing the wax. Once cooled, they knocked the shell away to reveal a replica of the original wax pattern.
This same process, though influenced by modern technology, is used to create marine stainless-steel propellers. We recently toured the Yamaha Precision Propeller Industries facility in Greenfield, Indiana, one of the newest investment-casting foundries in North America.…