Magnesium Machining and Casting Suppliers in Austin, TX

You use magnesium when weight is the dominant design driver and aluminum is already as light as it can go but still too heavy. Magnesium is about 35 percent less dense than aluminum, roughly 1.74 g/cm3 against 2.70, and on a stiffness-to-weight and strength-to-weight basis it is the best structural metal available, so a magnesium part can hit a weight target that an aluminum redesign simply cannot reach without losing stiffness. For Austin's EV and electronics work, where range and low-inertia motion are worth real money, those grams justify the extra cost. Magnesium also machines faster and easier than aluminum, with lower cutting forces and excellent chip formation, so machined precision parts can actually be cheaper to cut even though the raw material costs more per pound. The tradeoffs are real and you have to manage them: magnesium corrodes more readily than aluminum and must be conversion-coated, anodized, or painted and galvanically isolated in assembly, and machining it requires fire-safety handling for the flammable fines. The decision rule is straightforward. If your part lives in a weight-sensitive application like a portable electronic device, an EV bracket, a moving fixture, or an aerospace housing, and you have a supplier equipped to finish and handle magnesium properly, the weight savings are worth it. If weight is not critical or the part faces a harsh corrosive environment without good finishing, aluminum is the simpler and cheaper choice. Match the metal to whether grams genuinely matter.

These three grades cover wrought, cast, and high-temperature magnesium respectively, and they are not interchangeable. AZ31B is a wrought magnesium-aluminum-zinc alloy supplied as sheet, plate, bar, and extrusion. It machines and forms well, is the most weldable of the three, and is the grade you specify for parts that start from mill stock and get machined or fabricated, such as brackets, plates, and panels. It offers good strength for its weight at a reasonable cost. AZ91D is a die-casting alloy with higher aluminum content, around 9 percent, formulated for fluidity and consistency in high-pressure die casting; it is the choice for production-volume parts where you need thousands of identical thin-walled castings like electronics housings, covers, and powertrain components, and it has relatively good corrosion resistance and castability for a magnesium alloy. WE43 is a premium magnesium-yttrium-rare-earth alloy engineered for elevated-temperature performance: it retains strength and resists creep up to roughly 250 degrees Celsius, well beyond what the AZ alloys tolerate, which makes it the aerospace and defense grade for gearbox housings, transmission cases, and missile and helicopter components. WE43 costs several times more than the AZ grades, so you only reach for it when temperature, creep resistance, or aerospace certification genuinely require it. The practical selection: AZ31B for machined and fabricated stock parts, AZ91D for high-volume die castings, and WE43 strictly for high-temperature or certified aerospace duty. Always call out the exact grade and temper on the drawing, because the alloys differ in cost, castability, and mechanical behavior, and a substitution can leave a part unable to meet its requirement.

Magnesium machining carries a genuine fire risk, but it is well understood and routinely managed by shops equipped for it, so it is a handling discipline rather than a reason to avoid the material. The hazard comes from fine magnesium chips, dust, and fines, which are flammable and, once ignited, burn at very high temperature in a fire that cannot be extinguished with water; water actually makes a magnesium fire worse because the burning metal reacts with it to release hydrogen. Bulk magnesium and coarse chips are not the danger, the fine particulate is. A shop that works with magnesium controls this several ways. They use sharp tools and proper feed rates to produce larger, cooler chips instead of fine dust, since coarse chips are far less prone to ignition. They keep magnesium chip collection separate, dry, and clean rather than letting fines accumulate or mix with other metals or oils. They keep Class D dry-powder extinguishers rated for combustible metals on hand instead of relying on water or ordinary extinguishers. Many machine magnesium dry or with specific non-water-based coolants, because water-based coolant can react with fresh magnesium surfaces to generate hydrogen. They also avoid letting tools dull, because a dull tool generates heat and fine particles, the two things that start fires. The upshot is that magnesium is actually one of the easier metals to cut, with low cutting forces, fast speeds, and excellent surface finish, and the safety practices are standard for any shop that does this work. The real risk is a general shop with no magnesium experience trying it on a one-off, which is exactly why you should source magnesium parts through a supplier who runs it regularly and already owns the chip handling and suppression setup.

You protect a magnesium part with a deliberate finishing and assembly strategy specified on the drawing, because bare magnesium will not survive real-world exposure, especially in a hot, humid climate like Austin's. Magnesium sits very low on the galvanic series, so it corrodes readily in moisture and corrodes aggressively when it touches a more noble metal such as steel or aluminum without isolation, becoming the sacrificial anode in that pairing. The first line of defense is a surface treatment. Chromate or modern chromate-free conversion coatings passivate the magnesium and provide a base for further finishing. Magnesium-specific anodizing builds a harder, thicker protective layer for parts needing more durability. Powder coating or painting over a properly prepared and pretreated surface seals the part against weather and handling, and is common for visible or exposed components. The second, equally important line is galvanic isolation in the assembly. When magnesium contacts steel fasteners, aluminum mating parts, or other dissimilar metals, you must isolate the junction with coatings, isolating washers, or compatible hardware so moisture does not complete a galvanic cell that eats the magnesium. Designing for this means choosing compatible or isolated fasteners and avoiding direct dissimilar-metal contact at any point that can stay wet. The practical approach is to treat finishing and isolation as part of the part definition, not an afterthought: call out the conversion coat or anodize, the topcoat if needed, and the isolation hardware on the print, and use a finisher who has processed magnesium before rather than one who treats it like aluminum, because the chemistries and galvanic rules are different. Get that right and magnesium parts last; skip it and they fail fast.