Magnesium Suppliers in San Antonio, TX

Karl Gillihan

🪶 MAGNESIUM

Magnesium Machining & Supply for San Antonio's Aerospace Sector

Magnesium is the lightest structural metal in common engineering use, roughly two-thirds the density of aluminum, and that single property keeps it in the conversation for San Antonio's aerospace and defense work. Buyers here typically aren't chasing magnesium for cost; they're chasing it for the stiffness-to-weight payoff on housings, instrument frames, and rotorcraft components. Sourcing it well in this market means finding shops that understand both the alloy chemistry and the fire-safety discipline magnesium machining demands.

AS9100ISO 9001NADCAP

Why San Antonio Buyers Specify Magnesium

The driver in this region is weight. With Boeing's Globemaster and tanker sustainment work at Port San Antonio, Lockheed Martin's local footprint, and the broader military maintenance cluster serving Joint Base San Antonio, engineers are constantly trading mass for fuel burn, range, and payload. Magnesium delivers a density near 1.8 g/cm3 against aluminum's 2.7, so a bracket or housing redesigned in magnesium can shed close to a third of its weight without a major geometry change. The second driver is damping. Magnesium alloys absorb vibration far better than aluminum, which matters for avionics trays, camera mounts, and gearbox cases that sit in high-vibration environments. For a sustainment shop replacing a legacy cast housing, AZ91D often reproduces the original part's acoustic and damping behavior more faithfully than an aluminum substitute would. The practical limit is corrosion and cost. Magnesium needs proper chromate or anodic conversion coatings and careful galvanic isolation from steel fasteners, and the alloy itself runs more expensive than aluminum per pound. San Antonio buyers who specify it tend to do so deliberately, on parts where the weight or damping return justifies the extra finishing and handling.

01

AZ31B, AZ91D, and WE43 Compared

AZ31B is the wrought workhorse, supplied as sheet, plate, and extrusion. With roughly 3% aluminum and 1% zinc, it forms and welds reasonably and shows up in formed panels, brackets, and lightly loaded structural pieces. For San Antonio sheet-metal shops adding magnesium to an aluminum-heavy line, AZ31B is the most familiar starting point because it behaves like a softer, lighter aluminum on the brake. AZ91D is the high-pressure die-cast grade, around 9% aluminum, and it dominates cast housings, covers, and gearbox cases. Its high aluminum content gives good castability and strength but limits weldability, so design intent matters early. Local sustainment work that reproduces legacy cast magnesium components most often lands on AZ91D or its sand-cast cousins. WE43 is the premium aerospace and defense grade, alloyed with yttrium and rare earths for elevated-temperature strength and creep resistance up to about 250 C. It costs considerably more and is harder to source, but for helicopter transmission housings and high-temperature aerospace castings it is frequently the only magnesium that qualifies. Buyers should confirm a supplier's WE43 traceability and heat-treat capability before committing, since material certification is non-negotiable on these flight-critical parts.

02

Machining and Fire-Safety Discipline

Magnesium machines beautifully. It cuts fast, produces clean chips, and is gentle on tooling, which is why a well-set-up shop can run it at high spindle speeds with excellent surface finish. The catch is that fine magnesium chips and dust are flammable and, once ignited, burn at temperatures that water makes worse. A shop running magnesium needs dedicated chip handling, Class D extinguishing media on hand, and operators trained to keep dry chips from accumulating. For San Antonio buyers, this is the single most important supplier qualification question. Plenty of capable aluminum shops will not touch magnesium because of the housekeeping and insurance implications, while shops with aerospace pedigree often have the protocols already in place. When you request a quote, ask directly how the shop segregates magnesium swarf and what their fire plan is. The answer tells you immediately whether they run it routinely or are improvising. Tolerance-wise, magnesium holds precision well but has a high thermal expansion coefficient, so dimensional inspection should account for part temperature. On tight-tolerance avionics housings, expect the shop to let parts normalize before final CMM inspection rather than measuring straight off a warm spindle.

Frequently Asked Questions

It depends on how the part is made and how hot it runs. For a die-cast or sand-cast housing reproducing a legacy component, AZ91D is the default because its high aluminum content casts well and delivers solid room-temperature strength. If the housing sees elevated temperatures, such as a helicopter transmission case running near 200 to 250 C, WE43 is usually required for its creep resistance and rare-earth strengthening. For a formed or fabricated bracket built from sheet or plate rather than cast, AZ31B is the wrought grade to specify. Given San Antonio's concentration of rotorcraft and fixed-wing sustainment work, many local housings end up in AZ91D, but always confirm the original drawing's callout and any AS9100 or NADCAP traceability requirements before substituting. The certification chain matters more than the alloy choice on flight-critical hardware.

Magnesium machines safely when the shop has the right discipline, but it is not a material every shop will run. The risk is in fine chips and dust, which are flammable and burn hot enough that water and standard ABC extinguishers are dangerous on a magnesium fire; Class D media is required. A qualified shop segregates magnesium swarf from steel and aluminum chips, keeps dry chips from piling up, and trains operators on the fire plan. In San Antonio, shops with aerospace pedigree from the Port San Antonio and Joint Base San Antonio supply base often already have these protocols, while general-purpose job shops frequently decline magnesium work. When sourcing, ask the supplier directly how they handle magnesium chips and what their fire suppression setup is. A clear, practiced answer signals routine experience; hesitation signals you should keep looking.

Magnesium's density is about 1.8 grams per cubic centimeter against aluminum's 2.7, so on a part with identical geometry magnesium is roughly 33% lighter. In practice the savings are often a bit less because magnesium's lower strength sometimes requires slightly thicker walls or added ribbing to match an aluminum part's stiffness, so real-world weight reduction on a redesigned component typically lands in the 20 to 30% range. For San Antonio's aerospace and defense buyers, that translates into meaningful payload, range, or fuel-burn gains across an airframe when applied to housings, brackets, and instrument frames. The trade is cost and finishing: magnesium runs more expensive per pound and requires conversion coating plus galvanic isolation from steel hardware. The weight win is real, but it pays off best on parts where mass is genuinely the constraint.

Magnesium is reactive and will corrode quickly if left bare, so finishing is part of the spec, not an afterthought. The two common approaches are chromate conversion coatings, which give a thin protective and paint-ready surface, and anodic treatments such as the Tagnite or Keronite-style processes that build a harder, more durable oxide layer for demanding environments. Most aerospace magnesium parts then receive a primer and topcoat. Equally important is galvanic isolation: magnesium is anodic to nearly every other structural metal, so direct contact with steel fasteners or aluminum without isolation invites rapid galvanic corrosion. Designers in San Antonio's defense supply chain typically call out dielectric washers, sealants, or compatible fastener platings to manage this. When sourcing, confirm the shop can apply the specified conversion coating in-house or has a qualified local finishing partner, since shipping bare magnesium between vendors adds corrosion exposure.

Last updated: July 2026

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