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Machine Design

Magnesium Injection Molding Turns Out Lightweight Parts for Communication Gear

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One of the U.S. Army’s goals is to reduce the weight of equipment soldiers must carry by about 25%. One method of shedding some weight could entail replacing aluminum used on communication gear with parts made by magnesium injection molding, a process pioneered and refined by Phillips Plastics Corp., Hudson, Wis. ( In the process, magnesium chips are fed into a screw and barrel where they are heated and mixed into a semifluid state. This lets the material behave like a thermoplastic for more-controlled, laminar flow into the die than the liquid metals used in die casting. Resulting parts are net shape and need no secondary finishing operations. The process uses no ozone-depleting gases and parts are 100% recyclable.

Magnesium components have the same EMI and RFI-shielding properties as their aluminum counterparts and are just as durable. But, magnesium is both lighter and stronger than aluminum, so engineers can substitute thinner-walled components that weigh 30% less than aluminum versions. The parts can be coated to resist corrosion and weather, and the magnesium parts can be overmolded with plastics if needed. And despite preconceptions about magnesium, it is not very flammable. Tests show it does not ignite until it reaches 875°F and will not sustain combustion once the flame or heat source is removed.

Edited by Stephen J. Mraz

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