Metal Spinning vs Stamping
The same round part can be spun or stamped. One needs a mandrel and a week, the other needs a die and a quarter — here is how to tell which one your volume justifies.
Part of our metal spinning service: the comparison below is based on how we quote both routes in our Nanjing workshop.
The Comparison Buyers Actually Need
Both processes start with a flat blank and end with a round part. Everything that differs between them comes from one fact: spinning needs a mandrel, stamping needs a die set. A mandrel is a single turned piece of steel; a die set is two matched blocks with guides, springs and a press to run it.
| Factor | Metal spinning | Deep drawing / stamping |
|---|---|---|
| Tooling | One mandrel, often a few hundred euros equivalent | Die set plus press time, typically an order of magnitude more |
| Tooling lead time | 7–10 days | 6–12 weeks including tryout |
| Economic volume | 1 – ~5,000 pcs per year | From roughly 5,000–10,000 pcs upward |
| Unit cost trend | Falls slowly with volume; labour and machine time dominate | Falls sharply once the die is amortised; material and cycle time dominate |
| Change after approval | Re-machine the mandrel — days, low cost | Modify or rebuild the die — weeks, high cost |
| Wall thickness control | Thins slightly at the crown; typically within 10% of nominal | Thinning at the draw radius, controlled but harder to change |
| Strength | Cold-worked, continuous grain, no seam | Cold-worked with a drawn wall; may need annealing stages |
| Surface | As-spun tool marks removed by polishing; excellent for reflectors | Draw marks and die polishing lines; good for painted parts |
| Best shape fit | Domes, cones, dished ends, reflectors, low and medium volume | Shallow, high-volume parts: lids, pans, caps, shells |
The volume ranges above are typical, not absolute. A part with a tight tolerance and a simple profile can be stamped economically at 2,000 pieces; a large 1,200 mm head is effectively never stamped.
Where the Two Cost Curves Cross
Unit cost in spinning is roughly flat: material plus machine time plus finishing. Unit cost in stamping starts high because the die is spread over the order, then flattens out lower than spinning. The crossing point is your break-even volume.
As a rule of thumb for a part around 300 mm diameter in 1 mm aluminum: spinning wins below a few thousand pieces a year, stamping wins above roughly ten thousand. Between those numbers it depends on the die cost and how much of the cost your supplier is willing to amortise into the first order.
- Ask for the die cost separately, and for the amortised unit price at 1k / 5k / 20k pieces — not one number
- Ask what a design change costs after approval. On a die it is a rebuild; on a mandrel it is often a day
- Check whether your forecast is real. Dies are justified by committed volume, not by hope
- Consider spinning for launch volume and stamping later, once the design has stopped moving
A worked example
| Stage | Spinning route | Stamping route |
|---|---|---|
| Tooling decision | Mandrel cut in week 1 | Die designed, built and tried out over 8–10 weeks |
| First samples | Day 7–10 | Week 10–12, plus tryout iterations |
| 1,000 pcs | Competitive; tooling already paid | High unit price — die amortised over a small order |
| 10,000 pcs | Still competitive on simple profiles | Cheaper per part; die cost now spread thin |
| Design change at 5,000 pcs | Re-machine mandrel, resume in days | Die modification, weeks of downtime |
The Route Most Buyers End Up Taking
Launch with spinning, validate the market, then move to stamping once the design is frozen and the annual volume is real. The spun parts pay for the launch; the die pays for the scale. The only cost is qualifying a second process later — and by then you know the part sells.
We quote both routes when a part sits near the break-even, with the tooling cost shown separately so the comparison is honest. If stamping is the better answer for your volume, we say so — a customer who moves to the right process at 20,000 pieces comes back for the next project.
- Spun prototype → market test → die decision at 6–12 months
- Spin the low runners, stamp the high runner in the same family
- Use spinning for spares and legacy parts long after the die is retired
Questions Buyers Ask Us
Is a spun part weaker than a stamped one?
Can spinning hold the same tolerance as stamping?
What if my part is not perfectly round?
Does spinning waste more material?
Can you quote both processes?
Related Capabilities
More guides: Stainless Steel Metal Spinning · Aluminium Spinning Reflectors · Spun Tank Heads & Dished Ends · Low-Volume Metal Spinning · CNC Machined Aluminium Enclosures · Spinning Design Guide · Spun Cones & Funnels · Spinning for Lighting · Roof Vent Caps · Spun Drain Pans & Ice Tubs
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