Magnesium Parts Sourcing Eau Claire, WI

Karl Gillihan

🪶 MAGNESIUM

Magnesium Machining and Fabrication in Eau Claire, WI

Magnesium alloys occupy a narrow but critical band of the material selection chart: lighter than aluminum by roughly 35 percent, yet stiff enough for structural housings, orthopedic instrument handles, and gearbox covers where every gram of mass savings compounds across thousands of assembled units. Eau Claire's machining ecosystem, built around close-tolerance work for medical device OEMs and industrial equipment producers, gives procurement teams a regional source for magnesium components that meet both dimensional and surface finish requirements without shipping parts across the country. Understanding which alloy grade fits your application before you issue an RFQ shortens lead time and avoids costly material swaps mid-production.

ISO 9001ISO 13485AS9100

Heavy-equipment manufacturers in the Eau Claire region have long sourced precision-machined housings, covers, and bracket assemblies from local shops capable of holding tolerances in the +/-0.001 inch range on complex geometry. Magnesium entered that supply chain as OEM engineering teams pushed weight reduction into powertrain and cab components without sacrificing stiffness. AZ91D die-cast alloy, with its tensile strength near 34,000 psi and excellent castability, became a go-to for thin-wall housings where aluminum's higher density added measurable cost at scale. On the medical device side, Eau Claire suppliers serving surgical instrument and implantable-component customers have increasingly evaluated WE43 magnesium for resorbable implant applications. WE43's rare-earth additions (yttrium nominally at 4 percent, zirconium at 0.5 percent) produce a corrosion resistance profile far above standard magnesium alloys, and its degradation behavior in physiological environments is predictable enough for regulatory submissions. Shops processing WE43 must maintain dedicated tooling, separate coolant management, and dry-chip protocols — capabilities that ISO 13485-certified facilities in western Wisconsin have built into their quality systems. The Chippewa Valley's industrial base, anchored by equipment production and component manufacturing for national OEMs, creates steady demand for machined magnesium in batch sizes from 50 to 5,000 pieces. Buyers sourcing here benefit from shorter freight lanes, direct shop communication, and faster iteration on first-article parts compared to sourcing from coastal or international suppliers.

AZ31B Sheet and Plate: The Forming and Welding Grade

AZ31B is the most fabrication-friendly wrought magnesium alloy in common production. Its composition — roughly 3 percent aluminum, 1 percent zinc, 0.2 percent manganese — gives it enough ductility to be formed at elevated temperatures (typically 300 to 450 degrees F) without cracking, making it the preferred choice for enclosures, panels, and formed structural members that cannot be die-cast or machined from billet. Tensile strength runs approximately 38,000 psi with yield around 29,000 psi, placing it in a useful structural range for lightweight frames and support brackets. Welding AZ31B requires TIG process with AZ61A or AZ101A filler rod in an inert-gas environment; MIG is feasible on thicker sections but TIG produces cleaner beads with less porosity on the thin gauges (0.040 to 0.125 inch) common in enclosure work. Fabrication shops in the Eau Claire area that handle aluminum sheet work typically have the process discipline to transition to AZ31B with modest procedure qualification effort. Post-weld stress relief at 300 to 350 degrees F for one hour reduces residual stress concentrations at joint lines. For procurement teams, AZ31B plate is available from service centers in standard widths up to 48 inches; thicknesses from 0.25 to 3 inches cover most structural plate applications. Request material certs confirming composition to ASTM B90 and mechanical properties to ASTM B557 before releasing to production, especially for load-bearing assemblies.

Finishing, Coating, and Corrosion Protection for Magnesium Parts

Bare magnesium corrodes aggressively in humid or saline environments, so virtually every structural magnesium part leaves the shop with a surface treatment. Chromate conversion coating (per MIL-M-3171) provides basic corrosion protection and serves as a paint base; however, hexavalent chromium restrictions under RoHS and REACH push most new designs toward anodize (HAE or Dow 17 processes) or micro-arc oxidation (MAO), which builds a ceramic-like oxide layer 5 to 25 micrometers thick with significantly better corrosion resistance. For medical components, anodized or MAO-finished surfaces must be validated for biocompatibility under ISO 10993 if the part contacts tissue or fluids. Powder coat over a phosphate or anodize base layer is common for industrial housings where color coding and impact resistance matter. Electroless nickel plating is occasionally specified for magnesium bushings and bearing surfaces, but adhesion requires a zincate intermediate step and close attention to bath chemistry. Procurement teams in Eau Claire sourcing finished magnesium parts should verify that the supplier's coating vendor has experience with magnesium substrates specifically — aluminum anodizers do not automatically have the process knowledge for magnesium, and failures at the coating interface are the most common quality escape in magnesium fabrication supply chains.

AZ91D Die Casting and AZ31B Machining: Sourcing Considerations for Eau Claire Buyers

AZ91D is overwhelmingly a die-cast alloy — its 9 percent aluminum content gives excellent fluidity in the die and a fine-grained microstructure that produces good surface finish and pressure tightness. Tensile strength of approximately 34,000 psi and good hardness (around 63 Brinell) make it suitable for transmission covers, pump housings, and instrument cases where light weight and modest structural loads coexist. Regional buyers sourcing AZ91D castings should confirm the foundry's shot velocity and die temperature controls, since cold-shot defects in magnesium are harder to detect by standard X-ray than similar defects in aluminum. Machining AZ91D and AZ31B billet stock requires high-speed cutting (surface speeds of 1,000 to 3,000 sfm are common), sharp carbide or PCD tooling, and dry or mist cutting rather than flood coolant — water-based coolants risk hydrogen evolution at the chip pile if left unmanaged. Chips must be collected in closed steel containers and disposed of per OSHA 29 CFR 1910.119 protocols; most established precision shops in the region have chip-management procedures already in place from aluminum and titanium work. WE43 for medical applications commands a price premium of 8 to 15 times AZ31B sheet cost and requires dedicated process controls from bar stock through finished part. When qualifying a western Wisconsin shop for WE43 work, ask for their material traceability system, dedicated fixture sets, and documented cleaning procedures — contamination from ferrous chips causes galvanic corrosion that can compromise implant performance.

Frequently Asked Questions

AZ31B wrought plate and bar stock are the most readily sourced grades from regional distributors and machine shops in the Chippewa Valley. AZ91D is typically sourced as a die casting from foundries in the upper Midwest rather than machined from billet, since its primary value is in net-shape casting. WE43 bar and plate for medical applications is a specialty item — only a handful of western Wisconsin shops maintain the dedicated tooling, dry-machining protocols, and ISO 13485 quality systems required to process it correctly. When issuing RFQs, specify your alloy, temper (for wrought forms), and whether you need material certifications to ASTM B90 or AMS 4375 standards, as this affects both sourcing lead time and price.

Magnesium is approximately 35 percent lighter than aluminum by density (1.74 g/cc vs. 2.70 g/cc for 6061), which is the primary driver for its use in weight-sensitive housings, covers, and bracket assemblies. However, aluminum typically wins on corrosion resistance, weldability without specialized procedures, and fatigue performance in high-cycle applications. For heavy-equipment components that see moderate structural loads and benefit from mass reduction — instrument panels, cab trim brackets, small gearbox covers — AZ91D or AZ31B deliver a compelling weight-cost tradeoff. For parts in high-humidity environments or those requiring frequent welding repairs in the field, 6061-T6 or 5052 aluminum is usually the more practical choice. Eau Claire shops familiar with both materials can help you run a rapid trade study based on your load case and operating environment.

Magnesium chips and fine swarf are combustible — fine particles below 420 microns can ignite, and bulk chip piles can sustain a fire that cannot be extinguished with water or CO2. Wisconsin shops machining magnesium must comply with NFPA 480 (Standard for the Storage, Handling, and Processing of Magnesium Solids and Powders) and OSHA 29 CFR 1910.119 for process safety. In practice this means dry-machining or mist-only coolant, steel chip containers with lids, no open flames or grinding operations near the machining cell, and Class D fire extinguishers (dry sand or Met-L-X powder) staged in the work area. Shops that process aluminum and titanium regularly typically already have the infrastructure; ask specifically about their magnesium-specific fire plan before qualifying a new supplier.

Yes — magnesium's excellent machinability (it cuts faster and with less tool wear than aluminum at equivalent surface speeds) actually makes tight-tolerance work easier than with harder alloys. Experienced shops in the Eau Claire region routinely hold +/-0.001 inch on bored holes and +/-0.0005 inch on critical mating surfaces in AZ31B and AZ91D with sharp carbide insert tooling and proper fixturing. The main tolerance challenge is thermal expansion: magnesium's coefficient of thermal expansion (approximately 26 micrometers per meter per degree C) is higher than steel and slightly higher than aluminum, so in-process temperature control and final inspection at 68 degrees F reference temperature matter for parts with tight positional requirements. For WE43 medical components, first-article inspection against a full PPAP or AS9102 balloon drawing is standard practice.

Start by requesting the shop's quality certifications (ISO 9001 at minimum; ISO 13485 for medical; AS9100 for aerospace), their documented magnesium machining procedure including chip management and fire safety plan, and at least two reference jobs with similar material and tolerance requirements. Request a material traceability example showing the chain from mill cert to finished part number. For first production orders, require first-article inspection (FAI) with dimensional ballooning and material cert attached. Ask whether they use dedicated tooling for magnesium or shared tooling — dedicated tooling prevents cross-contamination issues, especially for WE43. Finally, confirm their coating or finishing vendor has specific magnesium experience, since this is the most common gap in otherwise capable shops.

Last updated: July 2026

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