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Manufacturing services
CNC turning and milling · From 1 part
Precision machined 303 stainless steel parts: special fasteners, fittings, bushings, shafts and threaded components, turned and milled from your file. Upload your CAD and order online, starting at a single part.
Shoulder screw
303 Stainless · Ø18 head with 6 mm hex socket · Ø12 × 40 mm shoulder · M10 × 1.5 thread
1 pc
$74.80 USD
per part
25 pcs
$13.84 USD
per part
-81.50%100 pcs
$11.67 USD
per part
-84.40%303 stainless steel (AISI 303, UNS S30300) is an 18-8 austenitic stainless with added sulfur so it cuts easily: it is the free-machining stainless. That is why it is used for turned parts with many operations, such as fittings, bushings, shafts, special fasteners and threaded parts. At PREMSA we CNC turn and mill it from your file, starting at a single part with an instant price.
Engineering-grade properties of 303 stainless steel, including mechanical, physical, and machining characteristics relevant to precision machined components. This data supports material selection for threaded, turned, and tight-tolerance parts.
Alloy Type
Austenitic Stainless Steel (18-8 with sulfur addition)
Primary Characteristics
Excellent machinability, good corrosion resistance, non-magnetic in annealed condition, reliable surface finish
Tensile Strength (Ultimate)
85 ksi (586 MPa)
Tensile Strength (Yield)
35 ksi (241 MPa)
Elongation at Break
50%
Hardness
Brinell 160 HB (max, annealed)
Density
8.03 g/cm³ (0.290 lb/in³)
Elastic Modulus
28,000 ksi (193 GPa)
Poisson’s Ratio
0.29
Thermal Conductivity
16.3 W/m·K
Coefficient of Thermal Expansion
17.3 µm/m·°C
Melting Range
1400–1450 °C (2550–2640 °F)
Machinability
Excellent (the free-machining stainless)
Formability
Moderate
Weldability
Not recommended (sulfur causes cracking)
Corrosion Resistance
Good in water and air; not recommended for seawater or harsh chemicals
Common Forms
Bar, rod, hex bar, shapes
Typical Applications
Fittings, bushings, shafts, special fasteners, threaded parts, valve parts
Material Composition
Iron (Fe): balance, Chromium (Cr): 17–19%, Nickel (Ni): 8–10%, Sulfur (S): 0.15–0.35%, Manganese (Mn): ≤2.0%
ASTM Standard
ASTM A582 / A276
Rating across key engineering and manufacturing criteria.
Strength
Weight
Machinability
Formability
Weldability
Corrosion Resistance
Thermal Resistance
Cost Efficiency
Upload your CAD file and get an instant price and delivery date. CNC turning and milling from one part to production.
We CNC turn and mill 303 stainless steel parts for machinery, process equipment, valves, instruments and assemblies.
Threaded fittings and adapters
Bushings and spacers
Shafts and axles
Special screws and bolts
Nuts, inserts and threaded parts
Valve and pump parts
Turned caps, plugs and covers
Instrument parts
Assembly components
Common questions about custom 303 stainless steel parts: properties, machinability, hardness, magnetism, welding, tolerances and cost.
303 is the stainless steel chosen when a part needs a lot of machining. Its sulfur breaks the chip and allows faster cutting with a good finish. It is available in round, hex and square bar.
At PREMSA Industries we machine 303 with CNC turning and milling from your file, from prototype to production.
303 is chosen when a part has to resist corrosion from water and air and needs a lot of machining.
If your drawing doesn’t specify tolerances, we machine to ISO 2768-m (medium). On dimensions you call out we can hold ±0.025 mm (±0.001 in), and critical dimensions are checked in inspection.
Sulfur forms small inclusions that break the chip. That is what makes it cut easily, and also what lowers its corrosion resistance somewhat and makes it unsuitable for welding. For parts that will be welded or used in harsh environments, another stainless grade is a better fit.
303 machines well in CNC turning, CNC milling, drilling and threading.
303 is not recommended for welding.
Because it is free machining, 303 is used in many turned CNC machined components.
303 is often the right choice when a part needs a lot of machining and must resist corrosion from water and air.