Brass CNC Machining and Supply in Fond du Lac, WI

The three primary brass grades used in precision manufacturing — C360 free-machining brass, C260 cartridge brass, and naval brass (C464) — serve distinct application profiles that buyers should match carefully to service environment and processing requirements. C360 (UNS C36000) is the most widely used brass alloy in CNC and screw machine production, for one dominant reason: it is the most machinable metal in common commercial use, with a machinability rating of 100 percent on the standard scale where 1212 free-machining steel is the reference point. The 2 to 3 percent lead content that earns C360 this rating acts as a chip-breaker, producing short, brittle chips that evacuate cleanly from drills, taps, reamers, and turning tools at very high cutting speeds — often 500 to 800 SFM for turning and 200 to 400 SFM for drilling. Lead also lubricates the cutting zone, reducing tool wear and improving surface finish. C360 is the default specification for valve bodies, fittings, threaded inserts, terminal blocks, lock components, and any high-production precision part where machining efficiency is the primary economic driver. Its corrosion resistance in freshwater, seawater, and many industrial environments is adequate for most applications, though its susceptibility to stress corrosion cracking in ammonia-containing environments limits use in some agricultural and refrigeration applications. C260 (cartridge brass, 70 percent copper, 30 percent zinc) prioritizes formability over machinability. Its excellent cold-working characteristics — deep drawing, stamping, and forming without intermediate annealing — make it the standard for shell casings, deep-drawn cups, and sheet-metal components. As a machining material, C260 is significantly more difficult than C360 due to its lack of lead — it produces long, stringy chips and requires sharper tooling and more controlled feeds to achieve equivalent surface finish. In the Fond du Lac region, C260 appears primarily in sheet form for stamped brackets, electrical enclosures, and formed hardware rather than machined bar components. Naval brass (C464, 59 percent copper, 40 percent zinc, 1 percent tin) was developed specifically for marine saltwater service, where zinc-bearing brasses are susceptible to dezincification — the selective leaching of zinc from the alloy structure that leaves a porous, weak copper sponge behind. The tin addition in C464 suppresses dezincification, extending service life of marine hardware — valves, fittings, ship fittings, and pump components — dramatically compared to standard brasses in seawater service. For Fond du Lac shops serving Mercury Marine and other marine OEM programs, C464 is the specified grade for any brass component that will be immersed in or frequently wetted by lake or seawater.

The productivity advantage of C360 brass in CNC and screw machine production is real and substantial — shops that run both brass and 304 stainless can typically produce 4 to 8 times as many brass parts per machine-hour as stainless parts of equivalent geometry. This productivity differential drives the economics of parts that could technically be made in stainless or steel but are specified in brass when corrosion resistance requirements are met: lock bodies, decorative hardware, fluid fittings, and electrical connectors are all cases where the machining efficiency of brass delivers cost advantages that outweigh the material premium over carbon steel. For CNC turning of C360 in the Fox Valley's precision shops, surface speeds of 400 to 800 SFM are standard for roughing with carbide inserts, with finishing passes at 600 to 1,000 SFM achieving Ra 16 to 32 microinch surface finishes in a single pass without secondary polishing. Diameter tolerances of ±0.0005 inch are held routinely on production runs, with bore tolerances for H7 and H8 fits achievable on boring and reaming operations. Thread cutting — both external and internal — produces crisp, clean thread profiles in brass without the torn threads that plague cutting of softer pure copper. Drilling and tapping brass is significantly faster and more reliable than stainless. Spiral-flute and straight-flute taps both work well in C360; tapping speeds 3 to 4 times faster than stainless are standard. For deep-hole drilling (depth-to-diameter ratios above 5), the clean chip formation of C360 reduces chip-packing risk substantially compared to aluminum or copper. Multi-spindle screw machines running C360 hex bar produce complex fittings with cross-drilled ports, internal threads, and external hex features in a single setup at rates that make brass components among the most cost-competitive precision machined parts available in the market.

Fond du Lac's manufacturing geography creates natural demand for brass in fluid handling applications — the freshwater environment of Lake Winnebago and the Great Lakes basin means that boat builders, marine engine suppliers, and watercraft equipment manufacturers all need corrosion-resistant metal for plumbing, cooling circuits, and bilge system components. C464 naval brass and C360 (for non-saltwater applications) fill this role in marine fittings: through-hull fittings, sea cocks, manifold bodies, and cooling circuit connectors are produced in brass for fresh and coastal waters. Heavy-equipment hydraulic systems also use brass in instrumentation ports, pressure gauge adaptors, push-to-connect fittings, and vent plugs where the combination of reasonable corrosion resistance, easy machining, and good thread strength makes brass the practical choice. These components see hydraulic oil rather than water, so dezincification is not a concern, and C360 is standard. OEM hydraulic component programs in the Fox Valley typically require dimensional conformance to SAE, NPT, or BSP thread standards, O-ring groove dimensions per SAE AS4716 face seal or SAE J514 bite-type standards, and pressure ratings verified by burst-test qualification. The automotive Tier supply chain in east-central Wisconsin uses brass for fuel system fittings, radiator petcock plugs, transmission fluid fittings, and sensor bosses where thread sealing and moderate corrosion resistance in glycol-water mixtures are required. Automotive programs add PPAP documentation, IMDS material declaration for RoHS/REACH compliance checking, and periodically raise lead-free specification requirements — a trend that is pushing some automotive brass applications toward C260 or low-lead alternatives as regulatory environments tighten.

C360's 2 to 3 percent lead content has faced increasing regulatory scrutiny driven by drinking water safety concerns. The Reduction of Lead in Drinking Water Act (federal, 2011 amendment) and NSF/ANSI 61 and 372 standards restrict lead content in brass for potable water contact to a weighted average of 0.25 percent, which effectively excludes C360 from drinking water plumbing applications. California Proposition 65 and similar state-level regulations additionally require warning labels on C360 products sold in certain contexts. For Fond du Lac shops and buyers, this regulatory landscape creates clear specification rules. Applications in potable water service — residential and commercial plumbing fittings, water meter components, and drinking water system hardware — must specify lead-free brass: C87850 (silicon brass), C89550 (dezincification-resistant low-lead), or BiSlide (bismuth-selenium) alloys that meet NSF 61 and NSF 372. These alloys machine less easily than C360 (machinability ratings of 60 to 80 percent versus 100 percent for C360) but are process-capable in shops with appropriate tooling and speed/feed adjustments. For non-potable applications — hydraulic fittings, marine hardware, industrial valves, and electrical components — C360 remains fully approved and widely specified. Buyers should confirm their end-use application and relevant jurisdictional requirements before specifying C360 for any application that might contact drinking water or face consumer product lead restrictions. ManufacturingBase supplier profiles note whether shops are qualified to produce both C360 and lead-free brass alternatives, allowing buyers to identify sources for both specification paths.