Magnesium Machining and Fabrication in Charleston, SC

AZ31B sheet and plate is the workhorse grade for Charleston's aerospace fabricators. Its magnesium-aluminum-zinc chemistry delivers a tensile strength around 260 MPa with elongation sufficient for formed brackets, rib doublers, and access panels — components that appear in the hundreds on a 787 airframe. The grade machines cleanly at high surface speeds when coolant management is correct, and local shops running five-axis equipment hold ±0.001-inch tolerances on AZ31B details without exotic fixturing. AZ91D dominates the die casting side of Charleston's supply chain. The higher aluminum content (9%) gives superior castability and a yield strength approaching 150 MPa in the T4 condition, making it a practical choice for automotive transmission brackets, valve covers, and structural inserts in instrument panel carriers. Tier suppliers shipping to Volvo's South Carolina plant rely on AZ91D where wall sections drop below 3 mm and cavity fill is critical. WE43 enters the picture on programs where operating temperatures exceed 150°C or where creep resistance over long service intervals is required. The yttrium-rare earth chemistry elevates the usable temperature range well past what AZ series alloys can sustain, and it sees growing use in aerospace gearbox housings and defense electronics enclosures cycling through wide thermal environments. Charleston's ITAR-registered shops handle WE43 billets sourced through qualified domestic suppliers, maintaining full material traceability from mill cert to final inspection.

Magnesium's combustibility is real but manageable with disciplined shop practice. The ignition risk is largely confined to fine chips and dust, not the solid workpiece. Charleston shops running magnesium production maintain dry machining as the preferred approach — water-based coolants can react with freshly cut magnesium to generate hydrogen, so when fluid is used, purpose-formulated mineral oils or specialized synthetic fluids replace standard water-soluble emulsions. Chip conveyors run continuously, and chip collection bins are metal-lidded and kept separate from other swarf streams. Cutting parameters for AZ31B and AZ91D favor high spindle speeds and aggressive feeds to produce thick, curled chips that are easier to control than fine powder. Surface speeds of 1,500 to 3,000 SFM are common on carbide tooling. Sharp, polished flutes and positive rake geometry minimize heat generation at the cutting edge. Local shops performing first-article inspections on aerospace details document chip character as part of their process control records, flagging any shift toward fine or powdery swarf as a process alarm. Fire suppression for magnesium shops requires Class D extinguishers — dry sand or approved powder compounds — not CO2 or water-based systems. Shops supplying Boeing Charleston must demonstrate these protocols during supplier audits, and the discipline built into those audits has raised the baseline safety standard across the region's magnesium-capable machine shops broadly.

Bare magnesium corrodes aggressively in the presence of dissimilar metals or salt-laden environments — a genuine concern in coastal Charleston where marine humidity is a constant factor. Chemical conversion coatings, anodizing, and polymer topcoats each play a role depending on the end application. Chromate conversion (where ITAR and environmental regs permit) provides a baseline barrier, while micro-arc oxidation (MAO) builds a ceramic-like oxide layer that can reach Rockwell hardness levels and dramatically improves wear resistance for structural interfaces. For aerospace brackets and panels destined for 787 installation, the finishing sequence typically runs from conversion coat through epoxy primer and topcoat — the same general sequence used on aluminum structure, adapted for magnesium's higher galvanic sensitivity. Paint adhesion on magnesium is excellent when the conversion coat prep is done properly, and the resulting corrosion protection meets Boeing's BMS specifications for interior and exterior structure. Automotive die castings in AZ91D typically receive a powder coat or e-coat finish applied by regional coating suppliers operating within the Charleston-North Charleston industrial corridor. Consistency of coating thickness — typically 60 to 120 microns — is verified by magnetic induction gauges, and cross-hatch adhesion testing to ASTM D3359 is standard on production releases.

Domestic magnesium billet and sheet is available through authorized distributors in the Southeast, but lead times for WE43 and specialty tempers can stretch 8 to 14 weeks when demand from aerospace programs spikes. Charleston procurement teams buying for 787 supplier work typically maintain safety stock agreements with their machining partners to buffer against mill lead time variability. AZ31B sheet in common gauges (0.040 through 0.125 inch) is more readily available and most Charleston shops carry standing inventory in H24 temper. For die casting work in AZ91D, tool amortization timelines matter: production tooling for a 200-piece-per-month instrument panel bracket typically amortizes over 18 to 24 months at automotive pricing, and Charleston's tier suppliers factor those tooling costs into their long-term supply agreements with OEM customers. Prototype and bridge tooling in soft aluminum or kirksite can be quoted in 4 to 6 weeks when a program needs cast parts before hard tooling is released. ManufacturingBase connects Charleston buyers to AS9100 and ISO 9001 certified magnesium suppliers across the region, with capability data — machine envelope, fire suppression certification, material traceability systems — verified before listing. Whether the requirement is a single AZ31B prototype bracket or a 5,000-piece annual run of AZ91D die castings, the platform surfaces qualified options without the cold-call sourcing process that burns procurement time.