Magnesium Machining & Supply for Fort Worth's Aerospace Sector

Fort Worth is one of the few cities in America where the single largest employer builds combat aircraft. The Lockheed Martin plant on the west side runs F-35 final assembly, and Bell's facilities turn out the V-280 and rotorcraft programs. That concentration of airframe and rotor-drive work creates a real, recurring need for magnesium where it earns its place: transmission and gearbox housings, where AZ91D and WE43 castings cut weight off the rotating-assembly support structure without giving up the stiffness those parts demand. Magnesium's density runs about 1.74 g/cm3, roughly two-thirds that of aluminum and a quarter that of steel. For a city whose flagship products are weight-constrained flying machines, that ratio is not academic. A gearbox housing or an avionics enclosure machined from AZ31B plate instead of 6061 aluminum can shed meaningful mass on a part that flies thousands of hours. The trade-off is corrosion sensitivity and a lower modulus, so designers in the Fort Worth supply base tend to reserve magnesium for protected, weight-critical internal structure rather than exposed skins. The automotive Tier suppliers in the broader DFW metroplex add a second pull on magnesium, mostly AZ91D die castings for steering-column brackets, seat frames, and instrument-panel beams. Between defense and automotive, a Fort Worth buyer rarely has to look far for a shop that already knows how to handle the metal safely.

AZ31B is the wrought workhorse, supplied as sheet, plate, and extrusion. With roughly 3 percent aluminum and 1 percent zinc, it forms and welds well and machines beautifully, which makes it the default for bracketry, enclosures, and formed panels. Fort Worth shops cutting AZ31B typically hold general tolerances around plus or minus 0.005 in and tighter where mating surfaces demand it, taking advantage of magnesium's excellent machinability to run high feeds. AZ91D is the casting alloy, the most common magnesium die-cast grade in North America. Its higher aluminum content (around 9 percent) raises strength and castability, and the controlled low-iron 'D' chemistry improves corrosion resistance over older AZ91 variants. This is the grade behind most automotive magnesium brackets and many aerospace housings produced near here. WE43 is the premium aerospace grade, alloyed with yttrium and rare-earth elements to hold strength at elevated temperature, up to about 250 C continuous. WE43 shows up in helicopter and fixed-wing transmission housings and missile components where heat and load coexist, and it is the grade Fort Worth defense buyers ask about most when AZ-series tempers run out of thermal margin. Grade choice usually starts with the load path and operating temperature, then folds in corrosion exposure and whether the part is cast or wrought. A good local supplier will push back on a spec that calls for WE43 where AZ91D would do, since the rare-earth alloy carries a real cost premium.

Magnesium machining is straightforward once a shop respects the fire hazard. Fine magnesium chips and dust ignite readily, and a magnesium fire cannot be put out with water, which violently accelerates it. Fort Worth shops that machine magnesium run dry or use mineral-oil-based coolant rather than water-based fluids, keep Class D extinguishers and dry-sand bins at the machine, and manage chips so they never accumulate as fine, dry piles. The practical upshot for buyers is that not every Fort Worth machine shop will quote magnesium even though they could cut it geometrically. The ones that do have invested in the housekeeping, fire suppression, and chip-handling procedures that make it routine. When you source magnesium parts locally, confirm the shop runs sharp tooling at high feed to produce coarse chips rather than fine dust, and that they segregate magnesium from any aluminum or steel grinding that could throw sparks. Welding magnesium is also common in fabrication-heavy Fort Worth, done by TIG with AC and argon shielding. AZ31B welds cleanly; cast grades need more care around porosity. Reputable local fabricators will provide weld procedure documentation, which matters when the part is headed into an AS9100 or ITAR-controlled aerospace program.

Bare magnesium corrodes, particularly galvanically when bolted against steel or aluminum, so finishing is part of nearly every Fort Worth magnesium job rather than an afterthought. The two dominant systems are chromate conversion coatings and anodizing-type treatments, often followed by epoxy primer and topcoat for aerospace parts. Conversion coating per the relevant aerospace and military specifications gives a paint-ready base and a measure of bare corrosion resistance. For defense work feeding the F-35 and rotorcraft supply chains, the finish callout is usually driven by the prime's spec rather than left to the shop. Buyers should expect to provide the full finish and identification requirements up front, since reworking a finish on a delivered magnesium part is costly. Many Fort Worth suppliers coordinate finishing through dedicated coaters in the metroplex who hold the right approvals, so lead time planning should include that hand-off.