The Investment Casting Process

1. Design-All castings start out with the customer's plans, blueprints, or specifications. Our experienced engineers work out design details with the customer and develop computer models of the cast part. Since every application has different requirements, our personnel are an invaluable resource in answering questions and providing design information.
2. Pattern-For every casting a wax pattern must be manufactured. By injecting wax into an aluminum die, a pattern is formed that is the exact replica of the part to be produced. The die can be manually operated to fully automatic, depending on the customer's requirements.
3. Assembly-The wax pattern is then attached to a large runner system called a tree. Many patterns are attached to the tree forming a cluster. A ceramic pouring cup, which will receive the molten metal, is attached to the top of the tree.
4. Investing & Stuccoing-The assembly of patterns is dipped repeatedly into an agitated vat of ceramic slurry (investment), drained, coated with a fine silica sand (stuccoing), and allowed to dry. This process is repeated using progressively coarser grades of sand until a self-supporting shell (approximately 3/8" thick) has been formed.
5. De-waxing-Once the shell has dried, it is placed into an autoclave where pressure and steam-heat remove the wax, leaving a hollow mold for casting.
6. Firing-The hollow molds are placed in a firing furnace and preheated to 1800 degrees Fahrenheit in order to crystallize the shell and prepare it to receive the molten metal.
7. Casting-Molten metal is then poured or cast immediately into the preheated molds. After the molds have cooled, the ceramic shells are removed from the casting by mechanical vibration, blasting and chemical cleaning.
8. Finishing-Parts are then cut from the assembled clusters and finished using a variety of cleaning operations similar to other casting processes. While some castings may be ready for use at this point, others require secondary operations including machining, polishing, plating, etc.
9. Inspection-Inspection is performed manually and using a computerized coordinate measuring machine to verify casting conformance to customer requirements. Craft Cast uses SPC methods to ensure consistent performance in all critical processes.