We began using Magnesium castings for multiple products over 30 years ago, most notably for our Maxi-Sump Oil Systems. Over that time, we've been able to better understand and develop the Magnesium castings, dies, and machining processes. Aircraft components need to be able to deal with harsh environments including cold temperatures at altitude, hot temperatures during long taxi, acidic oil buildup from non-use, etc. all while being unforgiving to any defective behavior. With over 750 Maxi-Sump systems in the field, we have an excellent level of knowledge as to the effects on Magnesium in aircraft use.

Magnesium alloy castings are used in aerospace applications because they offer a superior strength-to-weight advantage over aluminum and other materials. Our sand castings are alloy AZ92A-T6. This means that both Aluminum and Zinc are the most prevalent elements besides Magnesium in the casting. "T-6" refers to the heat treatment process performed on the raw castings. A T-6 heat treatment significantly increases the strength and hardness without altering the density.

Magnesium castings can be seen as a direct replacement for aluminum castings when a lightweight product is required. A typical cast Magnesium piece will have very similar strength properties to Aluminum. Magnesium also handles elevated temperatures like Aluminum and has similar hardness and elongation ratings. All this with a comparative weight savings of 35%. Magnesium castings also are able to be machined more quickly than aluminum while using less cutting fluid.

Magnesium does have some issues that are important to understand. Because of it's relative scarcity, raw material cost is higher for Magnesium than Aluminum. Also, whereas aluminum naturally builds it's own protective coating to fight oxidation, Magnesium requires an applied chemical process to resist oxidation and seal the surface. Unfortunately, this process turns raw magnesium from an attractive bright silver color to a less attractive grey/green.

As the use of composites has increased over the past 10 years to replace metals in various aerospace components, a few companies have attempted to use composites in the manufacturing of engine parts. To understand the effectiveness of composite engine parts, it's necessary to note the differences in composite properties - both positive and negative - compared with metals. Even the best composite structures still lack the significant strength and chemical resistance properties to be safely utilized in aircraft engine applications where high ambient temperatures can quickly degrade the structure. The chart below gives a good representation of the properties of each material. It shows that while composite/resin structures are significantly lighter per volume than aluminum, they weigh similarly to Magnesium, but give up significant strength and temperature ratings.