Magnesium Parts and Sourcing for Milwaukee, WI Manufacturers

Magnesium is safe to machine when the shop is set up for it, and it actually cuts very well with low cutting forces, excellent finishes, and long tool life. The real concern is the chips. Fine magnesium turnings and dust are flammable, and once ignited they burn at extreme temperatures that water intensifies rather than extinguishes, so a magnesium-capable shop runs sharp tooling to keep chips coarse, controls feeds to avoid making fines, segregates magnesium swarf from steel and aluminum chips, and keeps Class D fire suppression on hand. Milwaukee's deep machining bench includes shops that handle magnesium routinely, but not every shop does, so this is a material where you must qualify the supplier. Ask directly whether they machine magnesium regularly, how they collect and dispose of chips, and what fire-suppression they have in place. A shop that gives clear answers to all three is a safe partner; one that hesitates should not run your magnesium work no matter how good their tolerances are on other metals.

Choose magnesium when weight is the dominant driver and aluminum is not light enough. Magnesium is roughly 35% lighter than aluminum and about a quarter the density of steel, so on moving assemblies, brackets, housings, and structural components where reducing mass and inertia matters, it can deliver savings aluminum cannot match. That is exactly the pressure Milwaukee's automotive and powertrain suppliers face. The tradeoffs are real, though: magnesium costs more than aluminum, corrodes more readily and almost always needs a protective finish, requires special handling during machining, and has lower elastic modulus, so designs sometimes need geometry changes to recover stiffness. For a part where weight savings clearly justify the added cost and process care, magnesium wins. For a part where aluminum already hits the weight target, the extra complexity rarely pays off. The honest answer for many Milwaukee programs is that magnesium makes sense for a targeted set of weight-critical components rather than as a blanket aluminum replacement.

These three cover most magnesium work and they are not interchangeable. AZ31B is a wrought alloy supplied as sheet, plate, and extrusion, and it is the grade for formed, fabricated, and machined parts. It welds reasonably, forms when warm, and machines fast, making it the easiest entry point into magnesium. AZ91D is the dominant die-casting alloy, used for the bulk of magnesium castings such as housings, covers, and complex brackets made in volume; its high aluminum content gives good castability, and the 'D' designation means tightly controlled impurity levels for better corrosion resistance. WE43 is a premium rare-earth and yttrium alloy that retains strength at elevated temperatures where the AZ-series alloys soften, and it is used in aerospace and demanding high-temperature applications. WE43 costs substantially more, so it should be specified only when the application genuinely needs its high-temperature performance. Match the grade to the process: wrought and machined points to AZ31B, volume castings to AZ91D, and high-temperature or aerospace-grade needs to WE43.

In almost every real application, yes. Bare magnesium corrodes, and it is especially vulnerable to galvanic corrosion when it touches dissimilar metals such as steel or aluminum fasteners, so finishing is treated as part of the part's specification rather than an optional extra. Common protection systems include chromate-type conversion coatings, anodizing processes that build a harder protective layer, and powder coat or e-coat top layers for environmental durability. The right system depends on the service environment, from a sheltered interior bracket that may need only light protection to an exposed automotive underbody component that needs a robust multi-layer system. Design details matter as much as the coating: isolating the magnesium from steel and aluminum at joints with coatings, sealants, or non-conductive washers prevents galvanic attack, and that should be settled at the print stage. When you quote a magnesium part with a Milwaukee supplier, give them the service environment and the mating-metal and fastener details so they can recommend a finish that will actually last in the field.