Process Benefits of Graphite Permanent Mold Aluminum Castings
The graphite permanent mold casting process combines the low cost of machinable graphite molds with a high strength aluminum (356 T6) or zinc-aluminum alloy (ZA-12) to provide an economical alternative to other casting processes in annual volumes of 500-15,000 pieces per year.
The graphite molding process is rather simple. Two mold halves with cavities cut out in each half are pressed together and molten metal is injected into the mold under low pressure. The mold is then held together throughout the solidification stages of the casting. The mold halves are separated, the casting removed and the process is repeated.
- Cast precision to +/-.005 which reduces secondary machining
- Cast surface finish of 125 RMS or better
- Tooling cost savings is as high as 50% to 75% over die castings and other cost methods
- Excellent detailing and flatness
- Tooling lead times of only 3-6 weeks
- Porosity free castings
The graphite permanent mold process employs gravity pouring of metals using graphite molds. The castings produced have excellent grain structure and extremely low porosity which result in superior ductility and outstanding strength. The castings can be designed with thinner walls and less weight with good dimensional accuracy. Used primarily for low melting temperature metals such as: aluminum (356 T6) and aluminum zinc (ZA12), permanent mold castings produce excellent finishes and pressure tightness when compared to sand castings. Savings in reduced machining operations can also be realized due to the dimensional uniformity of the castings and details that can be cast in, as well as reducing some secondary operations such as polishing due to the excellent surface finish. Graphite permanent molds have a production life of 10,000-40,000 parts, casting sizes range from a few ounces to 25 pounds.
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 graphite permanent mold aluminium 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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