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CNC Machining Materials
Stainless steel is highly resistant to corrosion and rust, making it suitable for situations where a part may be exposed to the elements for a long period of time. Stainless steel is also fairly malleable and ductile. Fictiv offers multiple stainless steel alloys, including a food-safe variety.
The 300 series family (303, 304, etc.) are austenitic stainless steels (after their crystalline structure) and are the most widely produced grades worldwide. Austenitic stainless grades are known for their high corrosion resistance and high strength across wide temperature ranges. They are not heat-treatable except by cold working, and are generally non-magnetic.
400 series stainless steels are the martensitic family and not as common as austenitic grades. Martensitic steels are extremely strong and tough due to higher carbon content, but more susceptible to corrosion in certain environments. They can be heat-treated to greatly increase their hardness and are magnetic.
17-4 PH Stainless Steel is a high-strength, highly corrosion-resistant material that maintains its durability up to 1100°F. The PH in its name stands for precipitation-hardened, a type of treatment it undergoes to increase yield strength. It is magnetic and heat treatable to a hardness of approximately Rockwell C50.
Nitronic 60 is an excellent all-purpose material with superior wear and corrosion resistance. It has a yield strength nearly double that of SS 304 and SS 316, as well as superior oxidation resistance. Popular applications include fasteners, valve stems, seats, pins, bushings, bearings, shafts and rings.
303 Stainless Steel
Yield Strength (tensile)
Elongation at Break
McMaster Part Number
304L Stainless Steel
316L Stainless Steel
410 Stainless Steel
416 Stainless Steel
440C Stainless Steel
17-4PH Stainless Steel
The finish of stainless steel varies greatly depending on surface roughness, but it’s generally characterized as being more shiny than unfinished aluminum alloys, and slightly darker and more silver in color.
Stainless steel can also be media-blasted, sanded, hand-polished, and powder coated to achieve a multitude of surface finishes.
Min Wall Thickness
Min End Mill Size
Min Drill Size
Max Part Size
Radii : Depth
Cost Saving Tip
To reduce costs, limit the number of part setups, the number of inspection dimensions or tight tolerances, and deep pockets with small radii.
What is the best stainless steel for CNC machining?
There are four primary stainless steel grades that are best for CNC machining:
How thin can you machine stainless steel?
Thin walls require extra care when CNC machining stainless steel. The absolute minimum thickness is 0.5mm for metals. To minimize costs and machining time, it’s recommended to increase the thickness of thin walls to at least 0.8mm. Unless weight is a determining factor thicker walls are more stable and less costly. Thin features are susceptible to vibration, creating extra complexity and requiring considerably more time in machining operations.
Is stainless steel difficult to machine?
Yes, stainless steels tend to be one of the most difficult metals to work with in CNC machining. Stainless steel gets harder over time, instead of wearing, which combined with the high-heat generation in machining stainless steel, can contribute to tool failure. Getting speeds and feeds right as well as proper tooling is key.