Component Design Rules

Abstract

Semisolid Metal Processes generate near net-shape end products with a high degree of precision because they use hard steel tooling and high injection pressures. This combination results in a high level of replication of the die contours and generally the NADCA standards for “precision tolerances” can be achieved on a regular basis. It is important whenever possible to eliminate sharp corners and provide proper draft and radii that assist the smooth and complete filling of the die cavity under speeds associated with high production cycles. Such provisions will tend to extend die life as well as allow the manufacturers to make use of the natural advantages of the SSM processes. Wall thicknesses typically range down as low as 1 mm, depending on the alloy system used, part size and shape and of course the intended application. Apart from the linear dimensional tolerances, other tolerances will be additive, such as “Parting line, Moving die components, Angularity, Concentricity, Parting line shift, Draft requirements, Flat requirements, Cored holes for cut threads, Cored holes for formed threads, Cored holes for pipe threads, and Machining stock allowance” tolerances. The NADCA publication no: 403 on “Product specification standards for die castings produced by the semisolid and squeeze casting processes” provides a full list of tolerances for a variety of alloys systems [NADCA].