🪶 MAGNESIUM

Magnesium Machining and Sourcing in San Jose, CA

Magnesium is the lightest structural metal in common use, and in San Jose it tends to show up wherever engineers are fighting inertia or mass budgets rather than fighting load. Buyers sourcing AZ31B, AZ91D, or WE43 here are usually building handheld instruments, motion stages, or airborne hardware where stiffness-to-weight beats raw strength. This page covers how San Jose shops machine, cast, and finish magnesium, and what to verify before you release a job.

ISO 9001AS9100ITAR
Silicon Valley product engineering lives and dies on mass budgets. A handheld medical scanner, a drone gimbal, or a wafer-handling end effector all share the same problem: every gram of moving mass costs you in battery life, vibration, or settling time. Magnesium delivers a density of roughly 1.74 g/cm3, about two-thirds that of aluminum and a quarter that of steel, which is why San Jose's robotics and instrumentation startups keep it on the table even when aluminum would be cheaper to machine. The two workhorse grades you will source most often locally are AZ31B, a wrought magnesium-aluminum-zinc alloy that machines and forms well in plate and bar, and AZ91D, the dominant die-casting alloy for thin-wall enclosures. AZ31B is the go-to for machined brackets, optical mounts, and fixtures pulled from billet, while AZ91D shows up when a startup moves from a machined prototype to a die-cast production housing for a consumer or medical device. For defense and aerospace work flowing through San Jose primes and their subs, WE43 is the specialty grade. It is a magnesium-yttrium-rare-earth alloy that holds strength at elevated temperature and is qualified for aircraft transmission housings and missile components. WE43 is also biocompatible and bioresorbable, which is why a handful of Bay Area medical device teams evaluate it for temporary implants.

Machining Magnesium Safely and Cleanly

Magnesium is the easiest structural metal to cut. It has low cutting forces, excellent thermal conductivity, and produces clean chips that let shops run high spindle speeds and aggressive feeds. A well-tooled San Jose CNC shop can hold tight tolerances on magnesium with less tool wear than aluminum, and surface finishes come off the tool looking nearly polished. The catch is fire risk. Fine magnesium chips, dust, and grinding swarf ignite, and a magnesium fire cannot be put out with water or standard ABC extinguishers; it needs Class D media. Shops that machine magnesium routinely use flood coolant or dedicated mineral-oil coolant, keep feeds high to produce chunky chips rather than fine dust, and segregate magnesium swarf in covered steel containers. When you vet a San Jose shop for magnesium, ask directly whether they run it as a standard material or as a one-off; the difference shows up in their chip handling and fire procedures. Because of the fire-control and swarf-segregation requirements, not every general machine shop in the South Bay welcomes magnesium. The shops that do are usually the ones already serving aerospace and instrumentation accounts, so AS9100 and ITAR registration tend to travel together with magnesium capability here.

Finishing and Corrosion Protection

Bare magnesium corrodes, especially in coastal Bay Area humidity, so finishing is part of nearly every San Jose magnesium job rather than an afterthought. The most common protective treatment is chromate conversion coating per MIL-DTL-5541, though many buyers now specify hexavalent-free alternatives to meet RoHS and ISO 14001 expectations. For harder, more durable protection, plasma electrolytic oxidation and anodize-type coatings such as Tagnite and Keronite are used on aerospace and defense parts. Magnesium also accepts powder coat and primer-plus-topcoat systems well once properly pretreated, which matters for handheld consumer and medical enclosures that need a specific color and feel. The key is controlling galvanic corrosion: any time a magnesium part bolts to aluminum, steel, or stainless in an assembly, the joint needs isolation, because magnesium is anodic to nearly everything and will sacrifice itself at the interface. When you request a quote in San Jose, specify the finish and the mating materials up front. A shop quoting bare machined magnesium against a part that will see field humidity is quoting the wrong job.

Frequently Asked Questions

It depends on how the part is made and what it has to survive. If you are machining brackets, optical mounts, or fixtures from billet or plate, AZ31B is the standard choice; it machines and forms cleanly and is widely stocked. If you are moving a thin-wall enclosure into volume production, AZ91D is the dominant die-casting alloy and gives you good castability with reasonable strength. If your part is aerospace, defense, or a temperature-exposed component, WE43 is the high-performance grade that holds strength at elevated temperature and carries aerospace qualifications, though it costs significantly more and fewer shops stock it. For most San Jose robotics and instrumentation work, AZ31B covers machined parts and AZ91D covers cast production housings. Tell your supplier the application, the operating environment, and whether you are prototyping or producing, and a good shop will steer you to the right grade rather than just quoting what is on the shelf.
Yes, when it is machined by a shop that runs it routinely. Magnesium ignites only as fine chips, dust, or grinding swarf, not as solid stock, and experienced shops control that risk by running high feeds to produce chunky chips, using flood or mineral-oil coolant, keeping work areas clean, segregating swarf in covered steel containers, and stocking Class D fire extinguishers since water and ordinary ABC extinguishers make a magnesium fire worse. The real question for a buyer is not whether magnesium is dangerous in the abstract but whether your chosen San Jose shop treats it as a standard material. Shops that already serve aerospace and instrumentation accounts usually have the chip-handling and fire procedures in place. A general job shop that machines magnesium once or twice a year may not, so ask directly about their swarf segregation and fire suppression before releasing the job.
AZ31B in plate and bar is the most readily available form and many South Bay shops can pull it from regional metal distributors within a day or two. AZ91D is primarily a die-casting alloy, so you will source it as castings from a foundry rather than as billet for machining, and that supply chain runs on tooling lead times rather than stock. WE43 is a specialty aerospace alloy with limited distribution, often mill-direct or through specialty suppliers, and you should plan for longer lead times and minimum-quantity considerations. Because magnesium is a lower-volume material in general manufacturing, even AZ31B can carry longer lead times than aluminum during tight markets. The practical move in San Jose is to confirm material availability with your shop before you finalize a delivery date, and if your program is recurring, ask the shop to carry buffer stock of your grade so you are not exposed to distributor lead-time swings.
Plan the finish into the design, not after it. Bare magnesium corrodes readily, and Bay Area coastal humidity accelerates it, so nearly every San Jose magnesium part gets a protective coating. The common baseline is chromate conversion coating per MIL-DTL-5541, with hexavalent-free alternatives available for RoHS and environmental compliance. For tougher service, plasma electrolytic oxidation coatings like Tagnite or Keronite give a hard, durable layer, and many enclosures get powder coat or primer-plus-topcoat over a proper pretreatment. The other half of corrosion control is galvanic isolation: magnesium is anodic to aluminum, steel, and stainless, so any fastener or mating part needs isolation washers, coatings, or sealants at the joint to prevent the magnesium from sacrificing itself. When you quote a job, specify the coating and list every material the magnesium part contacts in the assembly so your shop can design the protection correctly.
For external medical hardware like handheld scanner housings and instrument enclosures, magnesium is a strong fit because of its low weight and good machinability, and you would treat it like any other enclosure material with appropriate biocompatible finishing. For implantable applications it gets more specialized. WE43 is biocompatible and bioresorbable, which has made it a research and clinical material for temporary implants and stents that dissolve in the body over time, and a few Bay Area medical device teams evaluate it for that reason. That said, implantable use pulls in ISO 13485 quality systems, full material traceability, and regulatory pathways that go well beyond standard machining. If you are building external medical hardware, most San Jose precision shops serving the device industry can handle magnesium under ISO 13485. If you are pursuing a bioresorbable implant, you will need a supplier with specific experience in medical-grade magnesium and the documentation chain to support a submission.

Related Pages

Magnesium in Los AngelesMagnesium in San DiegoMagnesium in SacramentoMagnesium in FresnoMagnesium in BakersfieldMagnesium in StocktonMagnesium CNC MachiningMagnesium Swiss MachiningMagnesium EDM / Wire EDMMagnesium Laser CuttingMagnesium Stamping

Last updated: July 2026

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