Designing with Investment Casting
When your design calls for a complicated, thin wall casting with undercuts, holes, bosses and hardness or strength requirements, investment castings may be the casting process for your parts. Simple designs are also cast using the investment casting process as well.
Sometimes referred to as lost wax process, the investment casting process begins with production of a heat disposable pattern, usually made of wax or plastic. The pattern is dipped into a refractory slurry and then, into fine sand. Once the slurry sets, the process may be repeated. The pattern is then melted out in a steam autoclave, leaving the ceramic mold cavity behind. After being hardened in a kiln at about 2000 degrees, the mold is ready for metal to be poured in. Once the metal cools, the ceramic shell is removed.
The investment casting process provides an exceptionally sound product with outstanding dimensional accuracy. Cast part dimensions vary less than +/- .001 from part to part. The process allows for components to meet x-ray and non-destructive testing specifications for military, aerospace and semi-conductor industries. It is also an ideal process for values, pumps, and many other industrial applications, as investment casting can produce complicated shapes that would be difficult or impossible with die casting. Investment casting provides excellent accuracy, repeatability, versatility and integrity with lower equipment cost.
Other advantages of the investment casting method are the various alloys cast. These include: stainless steel in 300 and 400 series, high temperature stainless steel such as : 15-5PH, 17-4PH for corrosive purposes; carbon steels 1020, 8620 and 4140 to name a few; very hard tool steels a1D2 among others and, all non ferrous alloys, aluminum 356, bronze, brass and copper.
In addition, investment casting parts can often be cast to net shape requiring minimal secondary machining, finishes 125 rms or better and internal coring for holes cast to desired diameter.
For more information , please use the alloy and process charts to best select an alloy to comply with your application needs. Be sure to also view our video on Investment Casting.
Please contact Dick Palmer for assistance with your casting project. PDF and 3D files of your design can be sent to: Palmer Associates, 142 Main Street, Suite 302, Nashua, NH 03060 or call toll free: (888) 494-0414
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