CNC Stainless Steel

Why Choose Stainless Steel

Corrosion Resistance

The chromium oxide passive layer formed on stainless steel resists oxidation, saltwater, chemicals, and most corrosive environments — making it the default choice for parts that must survive without surface coatings.
Strength and Hardness Retention at Temperature

Stainless steel retains mechanical properties at temperatures where aluminum and brass would soften. Grades like 17-4PH and 316L are commonly specified for parts operating above 200°C.
Hygienic Surface

Non-porous surface with no coating that can flake or contaminate — the reason stainless is mandatory in food processing, pharmaceutical, and surgical instrument applications.
Wide Grade Range

From free-machining 303 for threaded components to duplex 2205 for high-chloride offshore fittings — the right grade can be matched precisely to the corrosion environment and load requirement.
Aesthetic Appearance

Mirror polish, brushed, or bead-blasted finishes maintain appearance without additional coating. Electropolishing further smooths the surface and enhances corrosion resistance simultaneously.

Common Stainless Steel Grades

303

Free-machining grade — best chip-breaking of all stainless grades. Used for screws, shafts, fittings, and connectors where corrosion requirements are moderate. Not weldable.

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304 / 304L

General-purpose stainless — excellent corrosion resistance, good formability. The most widely used grade for structural parts, enclosures, and hardware not exposed to chlorides.

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316 / 316L

Marine-grade stainless — molybdenum addition improves chloride resistance significantly over 304. Standard for seawater-exposed hardware, medical implants, and chemical processing equipment.

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17-4PH

Precipitation-hardened stainless — combines high strength (up to 1,310 MPa UTS) with good corrosion resistance. Used in aerospace shafts, valve components, and surgical instruments requiring both strength and corrosion resistance.

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Duplex 2205

Dual austenitic-ferritic structure gives roughly double the yield strength of 316L plus better pitting resistance in high-chloride environments. Standard for offshore fittings, pressure vessels, and marine hydraulic components.

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Our Machining Capability

We machine all stainless grades — including hard-to-cut 17-4PH, duplex 2205, and 440C — on 100+ CNC machining centers with dedicated stainless tooling and coolant strategies. Tolerances held to ±0.005 mm on critical dimensions. Passivation is offered as a standard post-machining step for all stainless parts. All batches ship with material certs and CMM dimensional reports.
Limitations & Cost Considerations

Stainless steel machines slower than aluminum and generates more heat at the cutting tool — cycle times are longer and tooling costs are higher per part. Free-machining 303 is the exception; 316L and duplex grades are the most challenging to machine at high tolerances. Welded stainless may require post-weld heat treatment to restore corrosion resistance in the heat-affected zone. For purely structural applications without corrosion requirements, carbon or alloy steel is often a more cost-effective choice.

FAQ

What is the difference between 304 and 316L?

304 is the general-purpose grade — good corrosion resistance in most environments. 316L adds molybdenum, which improves resistance to chloride pitting significantly. If the part will be exposed to saltwater, seawater spray, or chloride-containing chemicals, 316L is the correct choice. For indoor or mild-environment applications, 304 is typically sufficient at lower cost.
Can you machine 17-4PH in the hardened condition?

Yes. We machine 17-4PH in both the annealed (Condition A) and precipitation-hardened (Condition H900–H1150) states. For best dimensional accuracy on complex features, we typically rough-machine in Condition A, heat treat to the specified H condition, then finish-machine to final tolerance.
Do you offer passivation as a standard service?

Yes. Passivation per ASTM A967 or AMS 2700 is available as a standard post-machining treatment. We re-measure critical dimensions after passivation where coating processes affect fit — passivation itself is a chemical process that doesn't add dimensional thickness but removes free iron from the surface.
Is stainless steel suitable for food contact applications?

304 and 316L are both FDA-compliant materials for food contact. 316L is preferred where cleaning chemicals (particularly chlorinated sanitizers) are used frequently. Surface finish matters: Ra ≤ 0.8 μm is the typical requirement for food contact surfaces to prevent bacterial adhesion. We can machine and verify Ra to this spec.