Stainless Steel CNC Machining
At Resolute Precision Manufacturing, we provide reliable stainless steel CNC machining services tailored for mission-critical and high-performance environments. Whether you need custom medical components, sanitary food-grade fittings, or structural marine hardware, our team machines a wide range of CNC stainless steel alloys to exact tolerances. Using high-precision Swiss lathes, multi-axis turning centers, and vertical mills, we deliver completely finished parts with full quality control, passivation coordinated per ASTM F86 and AMS 2700, and post-process finishing. Request a QuoteWhy Stainless Steel Requires Specific Machining Knowledge
CNC machining stainless steel requires a completely different approach than cutting carbon steel or aluminum. Austenitic grades like 303, 304, and 316 work harden quickly if setups are not dialed in. If an insert dwells or rubs for even a split second instead of cutting cleanly, the material glazes, dulling tools and leaving a rough surface finish.
Getting consistent results with CNC stainless steel demands rigid work holding, sharp tool geometries, positive chip engagement, and high-pressure coolant to keep temperatures in check. Our machinists develop custom feeds, speeds, and toolpaths for each specific alloy, ensuring your stainless steel CNC machined parts meet strict dimensional tolerances and clean surface finishes straight off the machine.
Our Stainless Steel CNC Machining Capabilities
Our precision stainless steel CNC machining covers the full path from raw bar to finished, passivated part. For small-diameter, tight-tolerance components, our stainless steel Swiss machining runs bar stock on 20mm–38mm Swiss lathes and completes turned, milled, and cross-drilled features in a single setup. Larger components move to bar-fed and chucked lathes for precision stainless steel turning, and to vertical and horizontal mills for multi-face geometry. Every order of stainless steel CNC machined parts is inspected against your print before it ships, whether it is a single prototype or a high-volume release.
Whether you need stainless steel CNC machining for prototypes or full production runs, we manufacture custom components based on your drawings and specifications. Before machining begins, we review each design for manufacturability to identify potential challenges. Our capabilities cover a wide range of parts, from miniature medical pins to marine shafts and manifolds for chemical processing applications.
Stainless Steel Grade Selection Guide
Selecting the right stainless steel grade is an important first step in producing a successful machined component, especially in custom CNC machining stainless steel projects where corrosion resistance, strength, and weldability must be balanced.
- 303 Stainless Steel — One of the most machinable austenitic stainless grades. Its sulfur addition improves chip breaking and machinability. It is generally selected for machined components where welding is not required.
- 304 and 304L Stainless Steel — Widely used stainless grades offering good corrosion resistance and weldability. They are commonly used for food processing, chemical processing, and general industrial applications.
- 316 and 316L Stainless Steel — Molybdenum provides improved resistance to chloride pitting and crevice corrosion compared with 304. These grades are commonly used in marine, medical, chemical processing, and other corrosive environments. 316L is the low-carbon version and is commonly specified for welded assemblies.
- 17-4 PH Stainless Steel — A precipitation-hardening stainless steel that can be heat treated to achieve high strength. H900 can reach approximately 200–220 ksi tensile strength depending on specification and condition. It provides a strong combination of mechanical strength and corrosion resistance for demanding applications.
- 15-5 PH Stainless Steel — A precipitation-hardening stainless steel offering high strength and corrosion resistance with good toughness. It is commonly used for aerospace, defense, and structural components.
Specifications
| Grades | 303, 304, 304L, 316, 316L, 17-4 PH, 15-5 PH; standard stocked grades with additional grades available upon request |
| Turning | Swiss CNC (20mm–38mm) for small-diameter parts; bar-fed and chucked turning for larger components |
| Milling | 3, 4, and 5-axis vertical milling; horizontal milling for multi-face parts and castings |
| Tolerances | ±0.001″ standard; ±0.0005″ on precision surfaces with appropriate process controls |
| Surface Finish | Ra 32–63 microinch standard; Ra 16 available with fine finishing; electropolishing coordinated through qualified outside service providers |
| Passivation | Coordinated per ASTM F86 and AMS 2700; standard for medical and food-contact stainless steel components |
| Heat Treat (PH Grades) | 17-4 PH (H900 through H1150) and 15-5 PH heat treatment conditions coordinated through qualified outside heat treatment providers |
| Volume | 1 prototype through high-volume production |
| Certifications | ISO 9001:2015 |
Stainless Steel Applications From RPM
We deliver high-tolerance stainless steel CNC machined parts across industries where part failure is not an option:
- Medical Devices: Precision 316L instrumentation, surgical tool bodies, and device components built to strict finish and cleanliness standards.
- Food and Beverage: 304 and 316 sanitary valve bodies, fluid connectors, and pump components designed to withstand daily washdown cycles.
- Marine Hardware: High-grade 316 deck hardware, shafting, and corrosion-resistant fittings engineered for saltwater environments.
- Chemical Processing: 316 and 316L manifolds, flow nozzles, and seals designed for aggressive fluid transfer.
- Aerospace and Defense: High-strength 17-4 PH and 15-5 PH brackets, pins, structural mounts, and custom fasteners built to rigid aerospace prints.
- Automotive: Sensor housings, fluid fittings, and precision shafts in 303 and 304.
- Fluid Power: Hydraulic and pneumatic fittings, manifold blocks, and valve components in 303, 304, and 316.
Industries We Serve
Aerospace & Defense
Medical Devices
Automotive
Fluid Power
Frequently Asked Questions
What is the difference between 304 and 316 stainless?
304 stainless provides good corrosion resistance in most environments. 316 stainless adds 2–3% molybdenum, which provides substantially better resistance to chloride pitting and crevice corrosion particularly important in marine environments, chemical service, and medical applications. 316L (low carbon) is specified for welded assemblies to prevent carbide precipitation at weld heat-affected zones.
What tolerances can RPM hold on stainless steel parts?
Our precision stainless steel CNC machining holds ±0.001″ as standard and ±0.0005″ on precision surfaces with appropriate process controls. Tighter requirements should be reviewed against your drawing.
Does RPM offer stainless steel Swiss machining for small parts?
Yes. Our Swiss lathes cover 20mm–38mm bars, which suit small-diameter, slender parts such as pins, shafts, and fittings. Larger parts run on bar-fed and chucked lathes.
Q: What is the hardest stainless grade RPM can machine?
A: We machine 17-4 PH in H900 condition (Rc 40–44) and 440C stainless in the hardened condition (Rc 55–60). Hardened stainless machining requires carbide tooling and specific cutting parameters — contact us for a feasibility assessment on hardened stainless components.
Why choose RPM for custom CNC stainless steel work?
We combine an ISO 9001:2015 quality system, Swiss turning and multi-axis milling under one roof, and coordinated passivation and heat treatment. Capacity runs from a single prototype to high-volume production of stainless steel CNC machining parts.