Stainless Steel CNC Machining
Stainless steel has become a pivotal material in CNC machining. This is owing to its unparalleled features of high strength, durability, and corrosion resistance. In high-performance applications like aerospace, medical, and food industries, stainless steel is a cornerstone material. It can withstand moisture, chemicals & tough environments. It maintains structural integrity even under high stress and temperature.
Common stainless steel grades for CNC machining include 303, 304, 316, 17-4 PH, 303, 416, 420, and 430. Each offers a unique balance of machinability, strength, and corrosion resistance to meet different industry needs.
Looking for high-precision custom stainless steel CNC machining services? Multi-Win provides expert CNC stainless steel machining with tight tolerances, smooth finishes, and quick lead times. Contact us today to get a free quote and explore how our stainless steel CNC machining services can support your project.
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Common Stainless Steel Grades for CNC Machining
Below is a list of widely used stainless steel grades for CNC machining with their key features and applications.
Stainless Steel 303
SS303 is a typical non-magnetic austenitic stainless steel in natural status. It is suitable for high-speed CNC turning and CNC milling parts owing to its strong machinability. And it is ideal for producing high precision complex parts with minimal tool wearing.
Properties:
- Best machinability in austenitic grade stainless steel
- Tensile Strength: ~620 MPa
- Yield: ~240 MPa
- Hardness: ~200 HB
- Non-Hardenable but can be improved by cold processing.
Typical Applications: Screws, fasteners, shafts, fittings, gears, non-critical automotive and aerospace parts
Stainless Steel 304
SS304 is another typical austenitic stainless steel. It has a good balance between corrosion resistance and workability, which makes it go for general-purpose use globally. This material is widely used for intricate CNC machined parts with post-welding or forming.
Properties:
- Non-magnetic in annealed state
- Excellent formability and weldability
- Tensile: ~520–750 MPa
- Yield Strength: ~215 MPa
- Hardness: ~170 HB
- Heat Resistance: 870°C (max up to 925°C)
Typical Applications: tanks, piping, trim, railings, surgical tools, implants, heat exchangers
Stainless Steel 316
SS316 has super corrosion resistance by molybdenum content. In extreme environments, especially where chlorides, acids, or saltwater are, SS316 is an ideal choice.
Properties:
- Adds ~2-3% molybdenum significantly improving resistance to localized corrosion
- Superior for marine, chemical, saline or chloride-exposed environments
- Tensile: ~515–760 MPa
- Yield: ~205 MPa
- Hardness: ~217 HB
- Best suited for harsh environments where corrosion is a concern.
- Ideal for medical or marine-grade CNC parts that require biocompatibility or saltwater resistance.
Typical Applications: Medical implants, MRI scanners, valves, pumps, boat fitting, offshore platforms, and equipment or CNC parts which require exposing to salt or acidic working conditions.
Stainless Steel 17-4 PH
17-4 PH is a martensitic precipitation-hardening stainless steel. It has a perfect balance of strength, toughness, and corrosion resistance in one alloy. During heat treatment, it has minimal distortion. It is suitable for manufacturing lightweight and high-strength hardened machined parts.
Properties:
- Magnetic
- Composition: ~17% chromium, 4% nickel, 4% copper, 0.3% Nb, and 0.07% C
- Tensile: ~930–1310 MPa (after aging)
- Yield: ~860–1170 MPa
- Hardness: up to 45 HRC
- Annealing: Heated to ~1,040°C, then rapidly cooled.
Typical Applications: Landing gears, turbine blades, surgical tools, valves, pumps, nuclear reactor components, and precision CNC machining parts with resistance to high stress and impact.
Stainless Steel 416
SS416 is a martensitic free-machining stainless steel. It contains sulfur (0.15% min), which helps improve chip-breaking and reduce tool wear significantly. It is suitable for large quantities and tight tolerances CNC machined parts.
Properties:
- Composition: ~12-14% chromium, 0.1-0.3% sulfur, low nickel (<1%).
- Best machinability in all stainless steels owing to high sulfur content
- Tensile Strength: ~550 MPa
- Yield Strength: ~275 MPa
- Hardness: ~200–240 HB (annealed)
- Magnetic: fully magnetic due to martensitic structure
Typical Applications: pins, bolts, spindles, shafts, screws, engine components, and non-corrosive fluid-handling system parts.
Stainless Steel 420
SS420 contains high carbon, offering good hardness and wear resistance. For CNC machining parts that need sharp edge retention or high surface hardness, it will be an ideal choice.
Properties:
- Composition: Chromium: 12–14%, Carbon: 0.15–0.40%
- Fully magnetic
- Can be heated up to 50~55 HRC
- Tensile Strength: ~700–900 MPa
- Hardness: up to 50–56 HRC(after heat treatment)
- Can’t be welded
Typical Applications: Knives, surgical tools, cutting blades, bearings, dental forceps, scalpels, industrial wear components.
If you want to know more Stainless Steel Grades, please check the form below:
| Grade | UNS | EN Equivalent | Key Features | Applications | Recommended Finishes |
|---|---|---|---|---|---|
| 303 | S30300 | 1.4305 | Excellent machinability, lower corrosion resistance | High-speed machined parts, fasteners | Polishing, Passivation |
| 304/304L | S30400/S30403 | 1.4301/1.4307 | General purpose, good corrosion resistance and formability | Kitchenware, architectural parts, food equipment | Polishing, Passivation |
| 316/316L | S31600/S31603 | 1.4401/1.4404 | Molybdenum added for enhanced corrosion resistance, marine use | Chemical processing, marine components, medical instruments | Polishing, Passivation |
| 17-4 PH | S17400 | 1.4542 | Precipitation hardening, high strength and corrosion resistance | Aerospace, nuclear, oil & gas | Heat Treatment, Passivation |
| 15-5 PH | S15500 | 1.4545 | Similar to 17-4 but with better toughness | Aerospace, pressure vessels | Heat Treatment, Passivation |
| 416 | S41600 | 1.4005 | Heat treatable, great machinability, magnetic | Gears, shafts, bolts | Heat Treatment, Passivation |
| 420 | S42000 | 1.4028 | Hardenable, high hardness, good wear resistance | Cutting tools, surgical instruments, valves | Heat Treatment, Polishing |
| 440C | S44004 | 1.4125 | High carbon, extremely hard, excellent wear resistance | Bearings, blades, molds | Heat Treatment, Polishing |
| 430 | S43000 | 1.4016 | Ferritic, magnetic, decent corrosion resistance | Home appliances, trim, automotive decorations | Polishing, Passivation |
| 2205 Duplex | S32205 | 1.4462 | Duplex steel, high strength, excellent corrosion resistance | Chemical plants, marine structures | Passivation, Sandblasting |
| 301 | S30100 | 1.4310 | High strength, good formability | Springs, fasteners, automotive parts | Polishing, Passivation |
Finishing Options for Stainless Steel CNC Machining Parts
The finishes for stainless steel parts will help meet the needs of both functionality and corrosion resistance while also improving aesthetic appearance. Below are several common finishes for consideration.
- Cold & Hot rolled annealed
- Polishing
- Plating
- Glass Bead Blasting
- Passivation
- Powder Coating
- Brushing/ Satin
- Matte: Tampico brushing or light polishing
- Mirror Polishing
- PVD Coating
- Embossing
The correct finish for stainless steel parts matches not only functional but also aesthetic requirements. If you still can’t decide which one is most suitable for your products, feel free to consult our professional technical team.
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Is Stainless Steel the Right Choice for CNC Machining?
Stainless steel is becoming a dominant material among CNC machining processes. It offers exceptional performance, adaptability, and longevity. By selecting the right type, stainless steel material plays an unmatched role in various industries. These include food, medical, aerospace, marine, and mold.
When to Choose Stainless Steel for CNC Machining?
1. High strength & load-bearing required
2. Long-term cost savings
3. Corrosion resistance critical
4. Hygiene or cleanability needed
5. Biocompatibility & recyclability goals
When to Avoid Stainless Steel for CNC Machining?
1. Lightweight: Stainless steel is much heavier than plastic, aluminum, and titanium. If one project has a lightweight requirement, it is better to use others instead.
2. Non-corrosive working conditions: If corrosion resistance is not necessary, aluminum, steel, or plastic can optimize cost savings even better.
3. High thermal or electrical conductivity is needed: Stainless steel has low conductivity, which is not suitable for cooling or heat sink products.
4. Magnetic Interference Concerns: Most stainless steels are magnetic. If the working condition doesn’t allow any magnet, we need to do an annealing treatment or use other materials instead.
Looking for high-precision stainless steel CNC machining services for your project? We specialize in custom stainless steel CNC machining parts with tight tolerances, fast turnaround, and reliable quality.
Contact us today to get a free quote and expert consultation tailored to your requirements.
