Magnesium Suppliers and Machining Partners in Baltimore, MD

The aerospace electronics work concentrated near the port and along the I-95 corridor leans heavily on weight reduction. A radar chassis, a targeting pod housing, or a soldier-worn computing module all carry strict mass budgets, and magnesium's density of about 1.8 g/cm3 lets designers hit those numbers where aluminum at 2.7 g/cm3 cannot. Just as important for shielded electronics, cast and wrought magnesium provides excellent electromagnetic interference attenuation, so a single machined enclosure can serve structural and EMI-suppression duty at once. Baltimore's mix of ITAR-registered shops means a buyer can keep a magnesium defense part inside a controlled supply chain from raw billet to finished, chromate-converted housing. That matters when the end item is destination-controlled hardware. The shops handling this work understand drawing callouts for conversion coatings, dissimilar-metal isolation, and the documentation trail that a prime contractor's quality group will audit. The practical takeaway for a local sourcing manager is that magnesium is rarely chosen for cost. It is chosen when the platform demands it, and Baltimore's defense and aerospace concentration produces a steady stream of exactly those demands.

AZ31B is the wrought workhorse, supplied as sheet, plate, and extrusion. With roughly 3 percent aluminum and 1 percent zinc, it forms and machines predictably and is the default for bent brackets, machined plates, and weldable structures. A Baltimore fab shop doing welded magnesium assemblies will almost always be working in AZ31B because it responds well to GTAW and holds tolerance through forming. AZ91D is the high-pressure die-casting grade, the one behind thin-wall electronics enclosures produced in volume. Its 9 percent aluminum content gives good castability and corrosion resistance for a magnesium alloy, and the D designation signals tightly controlled impurity levels for better corrosion behavior. Local buyers specifying a cast housing for a handheld or vehicle-mounted unit are typically looking at AZ91D, then sending castings out for finish machining of bores and mating faces. WE43 is the premium aerospace and increasingly bioabsorbable-implant grade. Alloyed with yttrium and rare earths, it holds strength at elevated temperatures up to about 250 C and is heat-treatable to higher yield. For Baltimore's higher-tier aerospace and medical work, WE43 is specified when service temperature or fatigue life rules out the AZ grades, and it carries a correspondingly higher price and longer lead time.

Magnesium machines fast and clean, but its fine chips and dust ignite, and a magnesium fire cannot be fought with water. Reputable Baltimore shops that quote magnesium have dedicated procedures: sharp tools to keep chips coarse, generous feed rates to avoid fine swarf, sealed chip containment, and Class D extinguishing media on hand. Coolant choice matters too. Many shops machine magnesium dry or with mineral-oil-based coolant rather than water-based emulsions that can react with fresh metal surfaces. Because of this, magnesium is not a material every CNC house will accept. When sourcing locally, confirm the shop has run magnesium before and segregates its chips. A shop that hesitates on the fire question is telling you something useful. The ones that quote confidently have the dust collection and housekeeping dialed in. Tolerances on machined magnesium are easy to hold because the metal is stable and cuts with low force. Bore tolerances in the 0.0005 inch range and surface finishes of 32 microinch or better are routine, which is why electronics housings with tight connector and gasket interfaces favor the material.

Baltimore's humid summers and the salt air around the harbor make corrosion protection non-negotiable for magnesium parts that see any field exposure. Bare magnesium corrodes readily, so finishing is part of the spec, not an afterthought. The common paths are chromate conversion coating per the relevant aerospace spec, anodize-type treatments such as the proprietary plasma electrolytic systems, and primer-plus-topcoat paint systems for outdoor or shipboard hardware. Dissimilar-metal contact is the other corrosion trap. Magnesium sits at the active end of the galvanic series, so any steel fastener or aluminum mating part needs isolation, typically a sealant, an insulating washer, or a sacrificial coating. Drawings for Baltimore defense work routinely call this out, and the finishing house needs to honor it. Local buyers should plan the finishing step into lead time. A bare machined housing might come off the mill in days, but the conversion coating and paint cycle, often subcontracted, adds a week or more and is where schedule slips tend to hide.