CNC Machining for Marine

Precision Manufacturing for Marine Hardware & Offshore Equipment

Marine components operate where corrosion, mechanical fatigue, and vibration hit simultaneously — and the wrong material grade or surface treatment choice shows up as a failed seacock or a leaking throughhull, not just a warranty claim.

Keywin manufactures precision marine hardware in 316L stainless, 5083 aluminum, bronze, and duplex stainless — from prototype first articles through production batches. Material selection and surface treatment are confirmed at the quoting stage, matched to each component's actual depth, chloride load, and pressure rating.

Marine

Typical Marine Parts We Manufacture

Valve Bodies & Seacock Fittings

316L stainless or bronze — tight bore tolerances for sealing surfaces; threaded ports in NPT, BSPP, or metric

Propulsion Shaft Components

Shaft couplings, flanges, keyways — concentric tolerances critical for vibration balance at speed

Hydraulic & Steering System Parts

Actuator bodies, cylinder end caps, manifold blocks — pressure-rated bore and thread accuracy

Deck Hardware & Cleats

Aluminum and stainless cleats, fairleads, hatch hinges — structural and corrosion requirements both

Underwater Fittings & Throughhulls

Bronze or stainless throughhull fittings, rudder pintles, propeller shaft seals

Navigation & Electronics Housings

Aluminum enclosures for marine electronics — IP-rated seal grooves, anodized finish for saltwater environment

Materials for Marine Applications

316L Stainless Steel (316L): Best general-purpose marine stainless — superior Cl⁻ corrosion resistance vs. 304

Marine Aluminum (5083, 6061, 5052): Hulls, superstructure, brackets — 5083 is the standard marine alloy for saltwater resistance

Bronze (C932 (SAE 660), C954 aluminum bronze): Traditional marine bearing and valve material — excellent saltwater corrosion resistance

Brass (C360, C464 naval brass): Fittings, valves, connectors in below-waterline applications — C464 has better saltwater resistance

Duplex Stainless (2205, 2507): High-pressure and high-chloride applications — offshore fittings, pump components

Titanium (Grade 2, Ti-6Al-4V): Highest corrosion resistance — used in high-value marine systems where weight also matters

Our Manufacturing Capabilities

Our machining capabilities cover the manufacturing of metal and plastic components, ranging from precision machining to surface finishing and assembly. We flexibly meet diverse needs—from single-piece samples to mass production.

CNC Precision Machining

High-precision 3/4/5-axis milling and turning supported.

Multi-Process Integration

Integrated manufacturing of forging, casting, injection molding, and sheet metal fabrication.

Surface Finishing

Anodizing, electroplating, powder coating, Dacromet, PVD, 20+ options.

Assembly & Packaging

Component assembly, functional testing, and customized packaging solutions.

Quality & Inspection System

We run a four-checkpoint quality system: incoming material inspection → first article inspection (FAI) → in-process sampling → outgoing quality control (OQC). Every step is documented and traceable.

On the equipment side: CMM coordinate measurement, optical projection, hardness testing, surface roughness gauging. We issue CMM reports, dimensional reports, and full-inspection records per batch. Tolerances are held to ±0.005–0.01 mm as standard, with tighter specs agreed at the quoting stage.

We support custom acceptance criteria and inspection plans built around your drawings — so the quality standard that matters to you is the one we actually measure against.

Service Process

01

Drawing Submission

Upload drawings with material specification, thread standards, surface finish, and corrosion environment notes.
02

Material Confirmation

We confirm marine-appropriate material and can advise on grade selection if required.
03

Prototype / First Article

Manufacture first-off parts with full dimensional inspection; send with CMM report before production proceeds.
04

Batch Production

Run production quantity with in-process sampling and thread gauge verification.
05

Surface Treatment

Apply specified anti-corrosion treatment; re-measure critical dimensions after treatment if tight tolerances are involved.
06

Packaging & Delivery

Corrosion-protective packaging; shipped via DHL/FedEx/freight as agreed.

FAQ

What's the difference between 304 and 316L for marine use — does it really matter?

Yes, and it matters a lot in saltwater. The key difference is molybdenum content: 316L contains 2–3% Mo, which dramatically improves resistance to chloride (salt) pitting corrosion. 304 is fine for fresh water and light atmospheric exposure, but 316L is the correct choice for anything in regular contact with seawater or marine atmosphere. For below-waterline components, we always recommend 316L as the minimum.
Can you machine bronze and brass fittings?

Yes. Bronze (particularly C932 bearing bronze and C954 aluminum bronze) and naval brass (C464) are regular materials for us. Both machine very cleanly and hold thread tolerances well. We machine throughhull fittings, valve bodies, and seacock components in these materials routinely.
Do you supply material certs for marine parts?

Yes. We can provide mill certificates for all marine-grade materials — 316L, 5083 aluminum, C932 bronze, etc. For high-value marine applications where material traceability is important, let us know at the quoting stage and we'll ensure the documentation package matches your requirements.
What surface finish is best for aluminum parts used on deck?

For above-waterline aluminum deck hardware: sandblasting + Type II anodizing gives the best balance of corrosion protection, appearance, and durability. For structural aluminum in high-wear areas: Type III (hard anodize) for the wear surfaces. If weight is critical and the part will be painted, a chromate conversion coat (Alodine) provides adhesion without adding significant thickness.

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