Squeeze Cast (SCPM) Light Weight Aluminum Front Knuckle Case Study 1999-01-0344

Squeeze Cast Permanent Mold (SCPM) is a premium grade aluminum casting process frequently used to produce safety critical aluminum suspension components. The emergence of SCPM as a major casting process for suspension components is relatively new in the high volume automotive market. Squeeze cast aluminum components have replaced iron/steel control arms and front knuckles in volume during the last four years.

In late 1994, Delphi Chassis Systems and Casting Technology Company (A joint venture between Amcast Industrial and Izumi Industries) began a joint development program for an aluminum front knuckle conversion slated for application on mainstream passenger cars. This was the first high volume production two-cavity squeeze cast aluminum conversion program of its kind. Previously, aluminum conversions on front knuckles were limited to comparatively small volume single platform programs. This joint program is applicable to volumes in excess of 1.5 million cars annually. Squeeze casting was selected based on the superior physical and mechanical properties, dimensional capabilities, integrated process controls, and previous success with the squeeze cast aluminum front knuckle used on other lower volume applications.

This paper will detail the history of the Delphi Chassis System/Casting Technology Company aluminum front knuckle conversion from cast iron to squeeze cast aluminum. The conversion process from concept design through continuous improvement will be described. Design and validation for simulated road performance relative to the aluminum conversion will be discussed as well as recent efforts to improve upon the design for an even lighter weight more near net product. Topics covered will include cast iron and squeeze cast aluminum comparisons of mass savings, near net shape, quality requirements, and processing differences from casting through final assembly.