Investment casting (lost-wax) is one of the oldest known metal-forming techniques. The term "lost-wax casting" can also refer to modern investment casting processes. From 5,000 years ago, when beeswax formed the pattern, to today’s high-technology waxes, refractory materials, and specialist alloys, the castings allow the production of components with accuracy, repeatability, versatility and integrity in a variety of metals and high-performance alloys. Lost foam casting is a modern form of investment casting that eliminates certain steps in the process.
Water glass and silica sol investment casting are the two primary investment casting methods nowadays. The main differences are the surface roughness and cost of casting. The water glass method dewaxes into the high-temperature water, and the ceramic mold is made of water glass quartz sand. The Silica sol method dewaxes into the flash fire, and silica sol zircon sand makes the ceramic mold. The Silica sol method costs more but has a better surface than the water glass method.
- Process Cost Roughness Tolerance Suitable material
- Water glass Cheap Ra6.4~Ra12.5 CT7,CT8 Carbon steel,Alloy Steel
- Silica sol High Ra3.2~Ra6.4 CT6,CT7 Stainless steel
Castings can be made from an original wax model (the direct method) or from wax replicas of an original pattern that need not be made from wax (the indirect method). The following steps describe the indirect process, which can take two to seven days to complete.
- Die design and tool-making
- Wax pattern injection
- Wax pattern assembly
- Dipping and stuccoing
- Wax removing
- Mold preheat
- Pouring
- Casting shake out
- Casting cut off
- Ingate grinding
- Sandblasting
Workshop:
