Sensor & Filter Housings
Thin-wall cylinders and cups with a closed end, trimmed square and deburred — ready for thread rolling, welding or clamp assembly.
Stainless Steel Metal Spinning
Seamless 304 and 316L spun parts with no weld seam, no draw marks and no tooling bill — from a single prototype to 5,000 pieces a month.
Part of our custom metal spinning service: 304 and 316 spun from Ø20 to 1,500 mm, 0.5–8 mm wall, on the same lathes and to the same tolerance.
Why stainless
One Piece of Metal, No Weld Seam
Stainless is the material buyers ask about most, and the one that punishes bad process choices hardest. Deep drawing 304 work-hardens fast and tears; welding a spun or pressed shell leaves a seam that has to be ground, pickled and re-passivated — and that seam is where corrosion starts.
Spinning forms the part from a single blank over a rotating mandrel. The wall stays continuous, the grain structure follows the shape instead of being cut across it, and there is nothing to weld, grind or re-passivate afterwards. For covers, bowls, housings and dished ends that see moisture, that difference shows up years later.
- Continuous wall — no circumferential weld, no heat-affected zone
- Cold working raises tensile strength instead of weakening the part
- Tooling is a mandrel, not a die set: typically a fraction of deep-draw tooling cost and 7–10 days to first sample
- Diameter 20–1,500 mm, sheet thickness 0.5–8 mm, tolerance ±0.1 mm on diameter
- Mirror polish, brushed, passivated or electropolished before packing
Grades we spin every week
| Grade | Where it is the right choice |
|---|---|
| 304 (1.4301) | General covers, housings, kitchen equipment, architectural parts — the default for good corrosion resistance at sensible cost |
| 316L (1.4404) | Food, pharmaceutical and coastal environments; low-carbon grade for parts that are welded or formed afterwards |
| 430 (1.4016) | Magnetic, lower-cost decorative covers and trim where 304 is over-specified |
| 321 / 310S | High-temperature exhaust and furnace parts; quoted on request |
| Duplex 2205 | Chloride-heavy service such as seawater-adjacent housings; limited to thinner sections |
Applications
Parts We Spin in Stainless
Bowls, Covers & Kitchenware
Serving bowls, pot lids, chafing dish covers and mixer bowls in 304, polished to a food-contact finish and passivated.
Cones, Reducers & Ducting
Concentric and eccentric cones for dust collection, exhaust and hopper transitions — with rolled or flanged ends as required.
Process control
What We Hold on Every Stainless Order
Stainless hides defects well until it is in service, so inspection is heavier than on aluminum. Each lot is checked at three points: incoming mill certificate and thickness, in-process diameter and wall thickness after spinning, and final dimensional plus surface inspection before packing.
| Specification | Capability |
|---|---|
| Diameter range | 20 mm – 1,500 mm (larger parts quoted individually) |
| Sheet thickness | 0.5 mm – 8 mm depending on diameter and grade |
| Diameter tolerance | ±0.1 mm on CNC-spun parts; ±0.3 mm on manual-spun large diameters |
| Wall thickness variation | Typically within 10% of nominal after CNC spinning |
| Squareness / runout | Trimmed and faced on CNC lathe to 0.1 mm where required |
| Surface | Ra 0.8 µm as-spun; Ra 0.2–0.4 µm on polished reflectors and covers |
| Documentation | Mill certificate (EN 10204 3.1), dimensional report, material traceability by heat number |
Send a 2D drawing with tolerances, or a STEP file plus a note on the critical faces. If the part is currently welded, we will tell you honestly whether spinning is cheaper at your volume — sometimes it is not.
Finishing
Finishes That Survive Shipping
Unpassivated stainless that has been spun and polished will show rust spots after a sea voyage. Every stainless part we export is degreased, pickled where weld-free forming has left embedded iron, and passivated in citric or nitric acid before it is wrapped.
- Passivation — citric or nitric, restores the chromium oxide layer after forming and polishing
- Mirror polish — progressive grits to a reflective finish for visible covers and reflectors
- Brushed / satin — directional grain for appliance and architectural parts
- Electropolishing — for pharmaceutical and ultra-clean surfaces, outsourced to a partner we have used since 2019
- Powder coating — any RAL colour over a pretreated surface when the stainless is chosen for strength rather than looks
Parts are packed with interleaved foam or VCI paper, in export cartons on fumigation-free pallets, and photographed before the carton is closed so you have a record of the finish as it left our floor.
FAQ
Questions Buyers Ask Us
Does spinning weaken 304 stainless?
The opposite. Spinning cold-works the material, which raises yield and tensile strength by roughly 10–20% in the formed wall. The trade-off is reduced elongation, so if the part needs heavy post-forming (rolling, flaring, deep flanging) we anneal it first or choose 316L, which forms more forgivingly.
Can you spin 316L without cracking?
Yes, with the right blank size, roller sequence and intermediate annealing on tight radii. 316L work-hardens faster than 304, so we plan two or three forming passes on deep domes rather than one, and we always run a first-article sample before committing to the batch.
What is the thinnest wall you can hold?
0.5 mm is our practical floor at diameters under 300 mm. Below that the part tends to chatter during trimming rather than during spinning. Above 800 mm diameter we prefer 1.0 mm minimum so the shell keeps its shape in transit.
Do you supply the material or should I?
Either. We buy 304/316L from Taiyuan and Baosteel distributors with EN 10204 3.1 certificates, and the mill certificate is passed on with the shipment. If your drawing specifies a mill and heat number, we can work with your nominated material on a buy-and-convert basis.
What is the minimum order for stainless spinning?
One piece for a sample or prototype. Stainless is priced by weight, so unit cost drops quickly once the blank nests well — most customers start at 50–100 pieces for a market test and scale from there.
Keep reading
Related Capabilities
Spun Tank Heads & Dished Ends
Hemispherical, 2:1 ellipsoidal and torispherical heads in 304/316 and carbon steel.
Read more →Spinning vs Stamping
Where the cost curves cross, and how to tell which process your part needs.
Read more →More guides: Aluminium Spinning Reflectors · Spun Tank Heads & Dished Ends · Low-Volume Metal Spinning · Metal Spinning vs Stamping · CNC Machined Aluminium Enclosures · Spinning Design Guide · Spun Cones & Funnels · Spinning for Lighting · Roof Vent Caps · Spun Drain Pans & Ice Tubs
Send Your Drawing for a 24-Hour Quote
Feasibility review, material advice and unit pricing — free of charge.