The main differences are the surface roughness and cost of casting. Water glass and silica sol investment casting are the two primary investment casting methods nowadays. Due to the hardness of refractory materials used, investment casting can produce products with exceptional surface qualities, which can reduce the need for secondary machine processes. The material is poured into a cavity in a refractory material that is an exact duplicate of the desired part. Many materials are suitable for investment casting examples are stainless steel alloys, brass, aluminium, carbon steel and glass. Investment casting derives its name from the pattern being invested (surrounded) with a refractory material. Lost-foam casting is a modern form of investment casting that eliminates certain steps in the process. Much of the wax used in investment casting can be reclaimed and reused. The fragile wax patterns must withstand forces encountered during the mold making. Investment casting is valued for its ability to produce components with accuracy, repeatability, versatility and integrity in a variety of metals and high-performance alloys. Today, more advanced waxes, refractory materials and specialist alloys are typically used for making patterns. In its earliest forms, beeswax was used to form patterns necessary for the casting process. Investment casting has been used in various forms for the last 5,000 years. The term 'lost-wax casting' can also refer to modern investment casting processes. Investment casting is an industrial process based on lost-wax casting, one of the oldest known metal-forming techniques. Inlet-outlet cover of a valve for a nuclear power station produced using investment casting

Investment casting of turbine blades