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The Reynolds’ 390 engine technology eliminates the need for iron bore liners in aluminum engines. This allows casting of the cylinder block and bores as an integral unit. The technology is a three-part system consisting of the hypereutectic 390 aluminum-silicon alloy, compatible pistons and a special cylinder bore finish. When properly applied, it can produce a lightweight, strong, compact and relatively low-cost aluminum engine block.

A small addition of magnesium (0.3%) to prime 380 die casting alloy (SAE 308) was found to improve the alloy's machinability. Magnesium hardens the matrix and by doing so reduces the tendency to build up on a tool edge, results in shorter and tighter chips, provides a better workpiece surface finish, giving prime 380 desirable machining characteristics similar to those of secondary alloy. However, tool wear rates for the magnesium-modified prime alloy were significantly lower than those for secondary alloy. Other minor/impurity element alloy variations also affected machining characteristics but less dramatically than the magnesium. Some elements traditionally credited with improving machinability were found in this study to be of little benefit.

The technical benefits of the SSM (Thixo) casting process for aluminum and other metals are now reasonably well understood; the process is able to make castings having thin walls, details, complexity and dimensional controls akin to conventional die castings, while using appropriate alloys, enabling heat treatment and providing part integrity, properties and consistency suitable for structural applications. Less well understood, however, are the inherent economics of the process; that is, material thrifting, energy conservation during parts manufacturing, long tool life and minimized secondary machining through net shape casting. The high cost of MHD billet for the process has here-to-fore been viewed as more than offsetting the inherent economics and has thus served to severely deter the widespread use of SSM components. Significant cost reductions via slurry approaches and/or other alternatives to MHD billet are major current thrusts.

High integrity aluminum castings are potential replacements for cast iron in current vehicle weight reduction programs. Domestically, several cast aluminum structural-type components are already realities, saving weight and contributing to improved fuel economy; wheels, brake drums, master brake cylinders and power steering housings. In Europe, suspension components, wheel hubs and disc brake calipers are cast in aluminum for some car models, indicating the functional and economic feasibility of such parts. Alloy and process technology already exist to enable production of realiable, high strength aluminum castings. Domestic automotive product engineers are urged to carefully consider and thoroughly test such aluminum castings along with the many other weight reduction possibilities currently being investigated.

Aluminum castings have much to offer the automotive industry in terms of weight reduction and energy savings. Their long-term acceptability can only be assured, however, by applying the most cost-effective combinations of material and processing. This paper will point out some “cost-saving” opportunities in two basic areas: (1) The use of hypereutectic aluminum-silicon alloys to eliminate a need for ferrous wear-surface inserts, to reduce machining capital expenditures and to reduce overall part weight; and (2) The use of two processing methods, “Pore-Free” die casting and “low-pressure” casting, to produce aluminum parts with minimum metal usage and energy consumption.