Why Marine Brass Demands Tighter Tolerances Than Standard CNC Parts Saltwater is a brutal environment. Standard brass parts corrode, seize, and fail within months. Our Cnc Machined Marine Hardware Bra
Saltwater is a brutal environment. Standard brass parts corrode, seize, and fail within months. Our Cnc Machined Marine Hardware Brass uses C46400 naval brass (copper-zinc-tin alloy) with a yield strength of 170 MPa and elongation of 30%. We hold tolerances at ±0.005 mm on critical sealing faces, which is 40% tighter than typical marine hardware specs. Runout on threaded shafts stays under 0.02 mm TIR. This is not decorative hardware — it is load-bearing, corrosion-resistant components for through-hull fittings, propeller shaft couplings, and deck cleats that must survive 10,000+ hours of salt spray testing.
We machine two primary alloys for marine use. C46400 naval brass offers 110 MPa tensile strength and resists dezincification — the #1 failure mode in sea water. C36000 free-cutting brass gives you 30% faster machining cycles but is only suitable for interior or freshwater applications. For exposed hardware, we default to C46400. Both alloys are stocked in round bar from 6 mm to 100 mm diameter, and hex bar from 10 mm to 50 mm across flats. Our precision manufacturing process holds surface finish at Ra 0.8 µm on sealing surfaces and Ra 1.6 µm on cosmetic areas. Hardness is certified at 75-90 HRB (Rockwell B), equivalent to roughly 20-25 HRC, which balances machinability with wear resistance.
Marine fittings fail at threads first. We cut threads with single-point CNC lathe tools, not taps, to achieve a 55° BSP taper or 60° NPT form with a pitch error under 0.01 mm over 20 mm of thread length. Sealing faces are machined with a wiper insert at 1,800 RPM and 0.05 mm depth of cut, producing a mirror finish of Ra 0.4 µm. This eliminates the need for thread sealant tape on most fittings up to 50 bar working pressure. We verify every thread with a calibrated ring gauge and every sealing face with a profilometer. If you need custom thread forms (metric, UNF, or left-hand), our CNC programs adjust within 24 hours.
Raw brass tarnishes in weeks. We offer two standard finishes. Yellow chromate conversion (MIL-DTL-5541) gives a golden tint and 96-hour salt spray resistance — sufficient for deck hardware. Electroless nickel plating (MIL-C-26074) adds 25 µm of hardness (up to 55 HRC equivalent) and pushes salt spray resistance to 500+ hours. For sacrificial anode compatibility, we can leave the brass bare or apply a clear lacquer. All finishes are applied in-house, which cuts lead time by 5 days compared to outsourcing. We carry a 1,000 kg inventory of pre-treated stock, so your Cnc Machined Marine Hardware Brass order starts the same day we receive your drawing.
Every batch — not every 10th part — gets inspected. We use a Zeiss CMM with 0.001 mm resolution to check critical diameters, thread pitch, and concentricity. A salt spray cabinet tests one sample per batch for 96 hours against your specified finish. Each shipment includes a dimensional report with actual measured values, a material certificate with heat number, and a hardness report. We retain test coupons for 12 months. If a part fails inspection, it is scrapped, not reworked. Our rejection rate for marine hardware is 0.3% — we know because we track it per customer.
| Parameter | Specification |
|---|---|
| Primary Alloy | C46400 Naval Brass (Cu 60%, Zn 39.25%, Sn 0.75%) |
| Secondary Alloy | C36000 Free-Cutting Brass (Pb 3.0%) |
| Bar Diameter Range | 6 mm – 100 mm round, 10 mm – 50 mm hex |
| Hardness (C46400) | 75-90 HRB (equivalent 20-25 HRC) |
| Dimensional Tolerance | ±0.005 mm (critical features), ±0.02 mm (general) |
| Surface Finish | Ra 0.4 µm (sealing), Ra 1.6 µm (cosmetic) |
| Runout (Concentricity) | ≤ 0.02 mm TIR |
| Thread Pitch Accuracy | ±0.01 mm over 20 mm length |
| Salt Spray Resistance | 96 hrs (chromate), 500+ hrs (electroless nickel) |
| Lead Time | 12 working days (standard), 5 days (rush, +20%) |
| MOQ | No MOQ — 1 piece to 100,000 pieces |
Most US or EU machine shops quote 4-6 weeks for marine brass. We ship from Dongguan, China in 12 working days for standard parts. Here is the breakdown: 1 day for program validation, 2 days for material cutting and preparation, 5 days for CNC machining (3-axis and 5-axis mills, Swiss lathes), 2 days for finishing and inspection, 2 days for packaging and export documentation. We keep 2,000 kg of C46400 bar stock on the floor at all times. For repeat orders, we store your fixtures and programs, cutting the next lead time to 8 days. Air freight to Los Angeles takes 3 days, to Hamburg 4 days. Total door-to-door: 15-16 days. Sea freight is slower but cuts shipping cost by 80%.
We do not enforce a minimum order quantity. This is uncommon for Chinese factories. You can order 1 piece for a prototype test or 50,000 pieces for a fleet retrofit. The price per piece drops predictably: 1-10 pieces costs 3.2× the 1,000-piece price; 100 pieces costs 1.5×; 1,000 pieces is the base line. Tooling is free for standard thread forms and diameters. For custom profiles, we charge a one-time programming fee of $150-400, which is waived for orders above 500 pieces. This model lets you validate a design without inventory risk. Many customers order 5 pieces, test them for 3 months, then scale to 5,000 units.
Send us your drawing in STEP, IGES, or PDF. We check for manufacturability within 4 hours — specifically draft angles, wall thickness, and thread depth. If your drawing has GD&T callouts that are over-constrained (e.g., flatness of 0.002 mm on a 100 mm surface), we flag it and offer an alternative. We machine threads up to M80 and through-holes down to 1 mm diameter. Wall thickness can be as thin as 1.5 mm without warping. We are experienced with the ASME Y14.5 standard and can interpret true position, concentricity, and profile tolerances correctly. For a deeper dive into how we choose cutting tools for brass, read our CNC cutting tool selection guide. To understand which tolerances are realistic for your design, check our CNC machining tolerances guide.
No MOQ — we machine a single prototype or a full production batch at the same quality standard, with only the per-piece price changing.
Yes — send us a sample or a material spec sheet, and we will source the exact alloy (including UNS numbers like C48500) and replicate the finish within 5 working days.
Every piece on orders under 20 pieces is inspected 100% with CMM and thread gauges; larger orders use a 5% random sample per batch, with full dimensional reports included.
Yes — for a 20% surcharge, we compress lead time to 5 working days on standard alloys, using pre-cut bar stock and overtime machining shifts.
We are BQUQ, a precision manufacturing factory in Dongguan, China with 20 years of CNC machining experience. We have shipped over 2 million marine brass parts to 14 countries. Our Cnc Machined Marine Hardware Brass is made in China, but inspected to ISO 2768-mK and ASME Y14.5 standards. No MOQ means you can test us with a single part.
Send your drawing to sc@bquq.com or WhatsApp +86 13713157787. You will get a firm quote with exact pricing, lead time, and finish options within 12 hours.
| Parameter | Capability |
|---|---|
| Materials | AL6061/7075, SUS303/304/316, 45# steel, T2 copper, H59 brass, POM, PEEK, nylon |
| Tolerance | ±0.005mm standard, ±0.003mm on request |
| Machines | 3/4/5-axis CNC, turn-mill, Swiss lathe |
| Surface | Anodizing, nickel, zinc, passivation, sandblast, polish |
| Size Range | Max 400 x 300 x 200 mm |
| Prototype | 72 hours, no MOQ on samples |
| Inspection | Full report per batch, CMM data on request |
