Stainless Steel CNC Machining Service
Plyconn machines corrosion-resistant stainless steel prototypes and production parts with controlled tooling, heat management, finishing, passivation, and dimensional inspection.
- Material-specific DFM and process selection
- Critical features down to ±0.01 mm after review
- Machining, secondary processing, and inspection
Stainless Steel CNC Machining Capabilities
Practical starting points; final capability depends on grade, condition, part size, geometry, finishing, and inspection method.
Why Use Stainless Steel for CNC Machining?
Material selection connects mechanical performance, service environment, manufacturability, finishing, availability, and total production cost.
Corrosion resistance
Chromium-rich passive films protect components in moisture, chemicals, food, medical, and clean-process environments.
Mechanical strength
Austenitic, martensitic, and precipitation-hardening grades cover a wide range of strength and hardness.
Temperature capability
Selected grades retain useful strength and oxidation resistance across demanding thermal environments.
Cleanability
Smooth, passivated, and electropolished surfaces support hygienic and vacuum applications.
Weldability options
304L and 316L are common choices where fabrication and corrosion performance must work together.
Finish versatility
Passivation, electropolishing, blasting, polishing, PVD, and plating support functional requirements.
CNC Machining Services for Stainless Steel Parts
We select the platform around geometry, datum relationships, access, size, batch volume, and manufacturing risk.
5-Axis CNC Machining
Complex housings, deep cavities, compound angles, and multi-face geometry tied to a common datum.
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Mill-Turn Machining
Rotational parts with flats, cross holes, pockets, threads, and back-working in one coordinated cycle.
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Swiss Machining
Small-diameter fittings, pins, inserts, connectors, and high-volume turned components.
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Electrical Discharge Machining
Conductive hard materials and features that are inaccessible to conventional cutters.
Explore service →Stainless Steel Grades for CNC Machining
International references are consolidated for sourcing comparison. Nominal equivalents can differ by chemistry, product form, condition, and governing standard.
| Grade | International cross-reference | Machining performance / behavior | Suitable applications |
|---|---|---|---|
| 303 | AISI 303 · EN 1.4305 · GB Y1Cr18Ni9 · JIS SUS303 | Excellent stainless machinability with short chips; lower corrosion and weld performance than 304. | Fittings, shafts, fasteners, valve and instrument parts |
| 304 / 304L | AISI 304/304L · EN 1.4301/1.4307 · GB 06Cr19Ni10/022Cr19Ni10 · JIS SUS304/L | Work-hardens during cutting; needs rigid setups, positive tooling, and consistent feed. | Food equipment, housings, semiconductor and general industrial parts |
| 316 / 316L | AISI 316/316L · EN 1.4401/1.4404 · GB 06Cr17Ni12Mo2/022Cr17Ni12Mo2 · JIS SUS316/L | More demanding than 304 due to work hardening and molybdenum; benefits from sharp tools and heat control. | Marine, chemical, medical, vacuum, and fluid-control parts |
| 17-4 PH | UNS S17400 · EN 1.4542 · GB 05Cr17Ni4Cu4Nb · JIS SUS630 | Machines well in solution-treated condition; final dimensions must account for the selected aging condition. | High-strength shafts, valve parts, aerospace and automation hardware |
| 420 / 440C | AISI 420/440C · EN 1.4021/1.4125 · GB 20Cr13/9Cr18Mo · JIS SUS420J1/SUS440C | Machining route depends strongly on hardness; grinding or EDM may follow heat treatment. | Wear parts, blades, seats, bearings, and precision tooling |
** Specify the governing standard, condition, product form, and certificate requirement. We verify equivalency before production.
Stainless Steel CNC Machining Tolerances and Part Sizes
Critical dimensions are reviewed against material condition, wall thickness, datums, tool access, temperature, and inspection method.
| Capability | Reference value | Application note |
|---|---|---|
| Typical tolerance | ±0.025 mm | For controlled drawing dimensions |
| Precision features | ±0.01 mm | Subject to geometry and inspection review |
| Surface finish | Ra 0.8 μm | Achievable on accessible machined surfaces |
| 5-axis envelope | 600 × 600 × 500 mm | Complex multi-face components |
| 3-axis travel | 1,000 × 600 × 600 mm | Plates, housings, and fixtures |
| Turning range | Ø3–300 mm | Pins, fittings, shafts, and sleeves |
| Geometric tolerance | ⏥ 0.02 mm | Typical position Ø0.03–0.05 mm |
| General tolerance | ISO 2768-mK | Unless the drawing specifies otherwise |
Surface Finishes for Stainless Steel CNC Machined Parts
Choose a finish by function first. Thickness, masking, and final dimensions are defined before machining where tolerances are affected.
As machined
Controlled cutting marks and deburring for functional parts.
No buildup. Deburring can soften small edges.
Passivation
Removes free iron and supports the natural corrosion-resistant surface.
Minimal. Negligible dimensional change.
Electropolishing
Smooths peaks to improve cleanability and corrosion behavior.
Removes material. Allow for controlled material removal on critical features.
Bead blasting
Creates a uniform matte appearance.
Minimal. Protect precision surfaces and sharp edges.
Mechanical polishing
Produces brushed through mirror-like cosmetic surfaces.
Removes material. Flatness and edge definition require protection.
PVD coating
Adds a thin hard wear-resistant decorative layer.
Allow for buildup. Typical coating is only a few micrometers.
Heat Treatment and Stability in Stainless Steel CNC Machining
Stainless heat treatment depends on alloy family, hardness target, corrosion requirement, and final dimensional risk.
Solution annealing
Used for selected austenitic grades to restore corrosion performance and dissolve detrimental phases.
Precipitation hardening
17-4 PH aging conditions balance strength, toughness, corrosion resistance, and dimensional response.
Hardening and tempering
Martensitic stainless grades are machined and heat treated according to the specified hardness.
Finish after heat treatment
Grinding, EDM, lapping, or final machining can restore critical dimensions after thermal processing.
Stainless Steel CNC Machining Project Examples
Examples of material selection, process planning, finishing, and inspection for common component types.
Fluid-Control Manifold
- Grade
- 316L
- Process
- 5-axis machining, passivation, CMM inspection
Ports, sealing faces, and cross-hole positions controlled for corrosion-resistant service.
Precision Valve Component
- Grade
- 17-4 PH
- Process
- Mill-turn, aging, grinding
Concentric sealing geometry and high strength coordinated through heat treatment.
Medical Instrument Part
- Grade
- 304
- Process
- Swiss machining, electropolishing
Small features, clean edges, and a controlled hygienic surface.
Quality Control for Stainless Steel CNC Machined Parts
Inspection is planned from the drawing. We identify datum access, measurement uncertainty, finishing state, sampling frequency, and required records before production.
Learn about our quality systemIncoming material control
Grade, condition, product form, heat or lot identity, and requested mill certificates are checked before release.
First article inspection
Critical dimensions, datums, threads, surface finish, and visual requirements are verified before batch production.
In-process verification
Machine probing, calibrated gauges, and scheduled checks monitor tool wear and dimensional drift.
Final dimensional inspection
CMM, optical, contour, roughness, thread, and conventional measurement are selected around drawing risk.
Available documentation
FAI, dimensional, CMM, material, finish, heat-treatment, and conformity records are available by requirement.
Repeat-order control
Approved programs, fixtures, inspection plans, revisions, and traceability records support consistent repeat production.
Our Stainless Steel CNC Machining Workflow
A clear workflow carries the project through engineering review, production, secondary processing, inspection, and shipment.
Upload files
Send CAD, drawing, material condition, quantity, finish, tolerances, and documentation needs.
Quote and manufacturability analysis
We review geometry, stock, tooling, distortion, datums, finishing allowance, inspection, lead time, and cost.
Machining and first article inspection
Material is released, setups are controlled, and the first part is inspected before the remaining quantity proceeds.
Heat treatment and post-processing
Approved thermal processing, deburring, finishing, marking, and cleaning are coordinated.
Final inspection and shipping
Dimensions, finish, appearance, documents, cleaning, and packaging are verified before shipment.
Stainless Steel CNC Machining FAQs
Which stainless steel is easiest to machine?
303 is commonly selected for high machinability. 304 and 316 provide broader corrosion performance but work-harden more readily.
Can machined stainless steel be passivated?
Yes. We plan cleaning, passivation standard, masking, and verification around the alloy and service environment.
Can you machine hardened stainless steel?
Yes, depending on hardness and geometry. The route may combine machining with grinding or EDM after heat treatment.
Discuss Your Stainless Steel CNC Machining Project
Send us your drawing, material, quantity, and quality requirements.
We’ll help define the next step.