🪶 MAGNESIUM
Magnesium Suppliers and Die Casters in Flint, MI
Magnesium is the lightest structural metal in volume use, roughly 35% lighter than aluminum, and Flint's automotive supplier base has every reason to care about it as weight targets tighten on EV platforms. Whether you need AZ91D die castings for a steering column bracket or WE43 plate for a higher-temperature application, this guide covers how buyers in Genesee County actually source magnesium and what to specify.
ISO 9001IATF 16949ISO 14001
Why Flint's Automotive Base Specifies Magnesium
Flint built its name on stamped steel body panels and powertrain components for GM, and that same engineering culture is what drives interest in magnesium today. When a Tier 1 supplier near Bristol Road needs to pull mass out of an instrument-panel cross-car beam or a seat structure, magnesium die casting is one of the few ways to consolidate a multi-piece steel weldment into a single net-shape part. AZ91D, the workhorse die-casting alloy at roughly 9% aluminum and 1% zinc, delivers good castability and corrosion resistance and is the grade most local buyers will reach for first.
The heavy-equipment work in the region adds a second pull. Magnesium gearbox covers, oil pans, and housings reduce mass on components where every pound off the top end helps fuel economy and handling. Because Flint shops already understand high-pressure die casting from aluminum and zinc work, the transition to magnesium tooling is less of a leap than it would be in a region without that base. The hot-chamber process used for magnesium runs faster cycle times than cold-chamber aluminum, which matters when a program calls for hundreds of thousands of parts a year.
Grade Selection: AZ31B, AZ91D, and WE43
AZ31B is the wrought grade, supplied as sheet, plate, and extrusion. With roughly 3% aluminum and 1% zinc, it forms and welds better than the higher-aluminum casting alloys and is the right choice when a buyer needs a bracket bent or machined from stock rather than cast. Local CNC shops can machine AZ31B at very high feed rates because magnesium cuts with about a quarter of the power that steel demands, though chip handling requires fire-safe practices.
AZ91D dominates die casting. It offers the best combination of strength, castability, and corrosion resistance of the common alloys, and its tightly controlled impurity limits on iron, nickel, and copper are what give it acceptable salt-spray performance for under-hood and structural use. WE43 is the specialty grade: a rare-earth magnesium alloy with yttrium and neodymium that holds strength up to around 250 degrees C, far above the 120 to 150 degree ceiling of AZ alloys. WE43 shows up in aerospace and defense gearbox housings and is the grade to call out when an application sees sustained heat that would creep an AZ casting.
Frequently Asked Questions
Flint and the broader Genesee County and mid-Michigan region have a deep die-casting base built around the automotive supply chain, and several casters run hot-chamber lines suited to magnesium. The most common production grade is AZ91D, used for structural brackets, housings, and covers where weight reduction matters. If you cannot place magnesium die casting locally, regional sourcing across southeast Michigan is straightforward, and Flint shops can still handle the secondary machining and finishing. When you request a quote, specify your annual volume, the alloy, wall thickness targets, and whether the part needs a corrosion finish, since magnesium nearly always requires a protective coating. ManufacturingBase can connect you with casters and machinists whose certifications and process capability match your program, including IATF 16949 shops feeding automotive Tier 1 work.
For die-cast automotive components, AZ91D is the default choice. It combines good castability with the corrosion resistance needed for under-hood and structural parts, and its controlled limits on iron, nickel, and copper are what make that corrosion performance reliable. For parts that are formed, bent, or machined from stock rather than cast, AZ31B sheet and plate is the better pick because it has superior ductility and weldability. WE43 is reserved for applications that run hot, above roughly 150 degrees C, such as certain gearbox or powertrain housings, because its rare-earth content lets it hold strength where AZ alloys would creep. Most Flint automotive work lands on AZ91D for castings and AZ31B for wrought parts, with WE43 only specified when temperature demands it. Always confirm the corrosion finish, since magnesium exposed to Michigan road salt without protection degrades quickly.
Magnesium has a density of about 1.74 grams per cubic centimeter versus roughly 2.70 for aluminum, so a direct material swap saves about 35% of the mass. In practice the savings are smaller because magnesium's lower stiffness and strength often require slightly thicker sections to hit the same load targets, so a realistic part-level reduction is usually in the 15 to 25% range over an equivalent aluminum design. The bigger win often comes from part consolidation: a single magnesium die casting can replace a multi-piece stamped-and-welded steel assembly, cutting both mass and assembly labor. For Flint suppliers weighing the change, the tradeoffs are cost, since magnesium alloy runs at a premium per pound, and corrosion management. When weight is the dominant driver, as on EV structural and seating components, magnesium frequently wins despite the higher material cost.
Magnesium is highly anodic and corrodes rapidly when bare, so any part exposed to road salt needs a multi-layer finish. The standard baseline is a conversion coating, either traditional chromate or one of the newer chrome-free chemistries, which passivates the surface and gives paint something to grip. On top of that, production automotive parts typically get an e-coat or powder coat to seal against moisture and chloride. Galvanic corrosion is a second concern: when magnesium contacts steel or aluminum fasteners, it becomes the sacrificial anode and corrodes preferentially, so designs need isolation washers, coated fasteners, or sealants at every dissimilar-metal joint. For Flint-area parts that see salt spray every winter, insist that your supplier validate the finish with salt-fog testing per ASTM B117 to a duration that matches your program's corrosion warranty.
Magnesium chips and fine dust are combustible, and that is the main reason not every machine shop will quote magnesium even when they run aluminum daily. The risk comes from fine, dry swarf that can ignite from a spark or from heat buildup with a dull tool. Shops set up for magnesium control it by running sharp tools, taking heavier cuts that produce larger chips rather than fine dust, keeping coolant flood or specialized non-aqueous coolant on the cut, and collecting chips in dedicated covered containers away from other metals. They also keep Class D fire extinguishers or dry sand on hand, never water, which reacts with burning magnesium. When sourcing CNC work in Flint, confirm the shop has machined magnesium in production before, not just spec sheets, since the handling discipline is what keeps the process safe and consistent.
Last updated: July 2026
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