Metal spinning is a proven method of forming sheet metal or cylinders into precise, hollow shapes such as cones, reducers, venturis, and other circular profiles. The process uses a metal spinning lathe, where a blank is held against a tool or chuck, and rollers form the metal as it spins at high speed. The result is a seamless or seamed part with exceptional strength and structural integrity.
While any ductile metal that can be cold formed by other methods can be spun, Church Metal Spinning specializes in stainless steel — particularly austenitic grades such as 304, 316, and 321, ferritic grades like 409 and 439, and low-carbon steels like ASTM A1008 and A1011. These materials offer excellent performance, but also present unique challenges that require specific design considerations.
Why Stainless Steel Presents Unique Challenges
Austenitic stainless steels have higher initial strength, are more abrasive, and are highly susceptible to work hardening. These characteristics demand greater forming force, tougher tooling, and precise process control. At Church Metal Spinning, our combination of equipment, skilled operators, and process expertise ensures consistent results, excellent surface finishes, and competitive costs.
Tooling: The Foundation of Quality Metal Spinning
The first step toward producing a high-quality spun part is starting with precision tooling:
- Springback Compensation: Tool design must account for material rebound after forming.
- Durable Materials: We generally use A2 tool steel, hardened to 60 Rockwell C, to withstand forming pressures and the abrasiveness of stainless steel.
- Precision Finish: A finely finished tool surface helps achieve the desired surface quality on the spun part.
Design Considerations for Manufacturability
While Church Metal Spinning does not offer full design engineering services, we provide valuable feedback to help improve manufacturability and reduce costs.
1. Transition Radii and Draft Angles
- Larger radii reduce stress on the material and tooling.
- Adding even a small draft angle to straight walls can simplify forming and reduce annealing needs.
2. Seamless vs. Seamed Designs
- Seamless Parts: Offer a uniform look but can see a 10%–50% reduction in wall thickness, depending on the design.
- Seamed Parts: TIG or laser-welded blanks can be cost-effective and allow for longer parts than spinning from a disc alone.
3. Material Thickness Variation
- Spinning down a cylinder increases thickness at the smaller end.
- Using multiple forming setups or incorporating annealing can reduce excessive thinning.
4. Managing Work Hardening
- Minimize the number of spin strokes to prevent rapid hardness increase.
- Cutting or punching features after spinning can cause distortion — plan carefully.
- Annealing between forming stages can restore ductility for deep or complex shapes.
Special Cases: Spinning Conical Shapes
Conical parts can be spun deeper than straight-walled cylinders. An included angle of 30° or more is ideal. For example:
- A part spun from 11-gauge stainless with a 30° angle may end up with a 0.028” wall thickness.
- The same part with a 60° angle could retain about 0.058” wall thickness.
Material Quality Matters
High-quality raw material improves surface finish, reduces scrap, and ensures consistency across production runs. At Church Metal Spinning, all materials are traceable back to their original mill certification.
Examples of Metal Spun Parts We Produce
- Heavy-Duty Reducer: 10ga 304L stainless steel, 11.5” deep, spun with a 2° draft to eliminate annealing; minimum wall thickness 0.090”.
- Airflow Component: 20ga 321 stainless steel, 35% thickness reduction, multiple forming stages with one anneal.
Metal spinning is a versatile and efficient process for producing stainless steel and other metal parts with precision and strength. By understanding how design choices impact manufacturability, part consistency, and cost, manufacturers can achieve better outcomes.
If you have a project that could benefit from our expertise, send us your print and specifications for a quotation on prototype or production runs.
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