Magnesium Machining and Casting Suppliers in St. Louis, MO

Magnesium is machined safely every day, but it requires specific practices because magnesium chips and especially fine dust are flammable, and a magnesium fire burns extremely hot and cannot be put out with water, which makes it worse by releasing hydrogen. Shops that handle magnesium routinely manage the risk through several measures. They machine with sharp tools and adequate feed rates to produce coarse chips rather than fine powder, because coarse chips are much harder to ignite. They control and promptly remove chip accumulation, and they keep magnesium dust collection separate from aluminum and other metals, since mixed metal dusts are especially hazardous. They keep Class D dry-powder fire extinguishers rated for combustible-metal fires available rather than relying on water or ordinary extinguishers, and they select coolants carefully because some water-based coolants can react with magnesium to release hydrogen gas. For a buyer, the takeaway is not to fear magnesium but to verify the shop's experience and setup. A shop that machines magnesium regularly will speak fluently about chip control, separate dust collection, and Class D suppression, while one that has barely touched the material may not have the dedicated practices in place. In St. Louis, the aerospace-tier shops that handle magnesium do so with the proper discipline, so the key is sourcing to those experienced shops rather than a general job shop improvising.

Magnesium is one of the most chemically active structural metals, which means bare magnesium corrodes readily in the presence of moisture and is especially vulnerable to galvanic corrosion when it is in electrical contact with a more noble metal like steel, aluminum, or a fastener. In a galvanic couple, magnesium becomes the sacrificial anode and corrodes preferentially, sometimes rapidly. Because magnesium parts rarely exist in isolation, they are usually bolted, mounted, or assembled against other metals, this galvanic risk is a constant design concern. Protection is therefore essentially mandatory: magnesium parts typically receive a chromate or chromate-free conversion coating to passivate the surface, followed by a primer and topcoat system, and the aerospace specs call out these coatings explicitly. Equally important is galvanic isolation at interfaces with dissimilar metals, achieved through coatings, sealants, insulating washers, or non-conductive barriers, so that the magnesium is not in direct electrical contact with steel or aluminum. A buyer must treat the corrosion protection and isolation as integral to the part, not optional finishing, and require certification that the conversion coating was applied to the specified standard. An inadequately protected or poorly isolated magnesium part will corrode in service in a way that is both predictable and traceable to the missed protection step, so this is one area where cutting corners reliably causes field failures.

The alloy depends on the form and the application. For wrought parts, made from sheet, plate, bar, or extrusion and then machined or formed, AZ31B is the common general-purpose magnesium alloy, offering a good balance of strength, formability, and weldability for structural brackets, panels, and machined components. For die castings, which make up much of magnesium's volume in both automotive and aerospace, AZ91D is the dominant alloy, used for housings, gearbox and transmission cases, instrument-panel structures, and similar cast components where its castability and corrosion behavior suit high-volume production. Where higher strength is needed, ZK60 is a wrought alloy strengthened with zinc and zirconium, used for forged and extruded high-performance parts. For elevated-temperature applications such as certain aerospace transmission and engine-adjacent housings, rare-earth-containing alloys like the WE and EZ families provide better high-temperature strength and creep resistance, but they are more specialized and costly. For most St. Louis sourcing the practical answer is AZ31B for wrought machined parts and AZ91D for die castings, specified to the appropriate standard with the temper or casting condition stated. Confirm the alloy and condition with a material certification, since magnesium's mechanical and corrosion behavior depends on getting the specified alloy, and require the conversion-coating certification alongside it.

Magnesium is a specialty material with a narrow supplier base everywhere, including St. Louis, so the decision depends more on finding a genuinely qualified and equipped shop than on geography. The region's aerospace and defense heritage means there are shops that machine and handle magnesium with the proper safety and corrosion-control discipline, and for aerospace work the engineering proximity to a program during qualification and first-article is valuable, which argues for local sourcing when a capable shop exists. The catch is that the field is small, so you may have limited local options and should qualify the shop's magnesium experience carefully rather than assuming any aluminum shop can pivot to it, given the flammability handling and corrosion-protection requirements. For magnesium die castings at automotive volumes, the specialized die-casting houses that pour magnesium are a limited national set, so high-volume cast work may route to a national or regional die caster regardless of where machining happens. Raw magnesium stock and castings often come through specialized national suppliers in any case. A reasonable approach is to source the casting or stock through the established specialty supply chain while keeping machining and finishing with a local shop that has the proper magnesium handling and conversion-coating capability, capturing the engineering-proximity benefit where it matters most. Whatever the choice, the shop's demonstrated magnesium experience and the corrosion-protection documentation matter more than location.