What is a servo press?

A servo press uses servo motors for precise force and position control during forming operations.

How do I calculate servo press tonnage?

Use our free tonnage calculator at servopress.club/tonnage-calculator.html

Stainless cookware deep draw on servo - setup help

marco_press

We make stainless steel cookware and want to try deep drawing on our servo press instead of the hydraulic. Anyone done this? What's the setup like?

**Material Challenges
**
304 stainless steel (the most common cookware material) work-hardens rapidly during forming. This means:
- Forming force increases as the draw progresses
- Risk of splitting increases in later draw stages
- Multiple draws with annealing between stages are often required

**Single-Draw vs Multi-Draw
**
For a typical pot (diameter 200mm, depth 100mm, draw ratio 0.5):
- Single draw: possible with servo press using slow speed and high blank holder force
- Two-draw: more reliable, better surface finish, less risk of splitting

**Servo Press Setup for Single Draw
**
**Blank holder force:** 25-35% of forming force for 304 stainless.

**Forming speed:** 20-40mm/s. Slower than steel because stainless work-hardens faster.

**Dwell at BDC:** 100-200ms. Reduces springback and improves dimensional consistency.

**Lubrication:** Heavy-duty drawing compound with EP additives. Apply to both blank surfaces at 4-6 g/m2.

**Die Design Notes**

- Punch radius: minimum 4x material thickness (too small causes splitting)
- Die radius: 6-8x material thickness
- Die clearance: 110-115% of material thickness (slightly more than steel to reduce friction)
- Die material: D2 or M2 tool steel, polished to Ra 0.4 μm

**Quality Issues
**
**Orange peel surface:** Blank holder force too high, or material grain size too large. Reduce blank holder force 10%.

**Wrinkling in flange:** Blank holder force too low. Increase 10%.

**Splitting at punch radius:** Punch radius too small, or forming speed too high. Increase radius or reduce speed.

toolndye_dave

304 SS cookware drawing is all about the blank holder. Too much pressure and the flange locks up and the punch tears through the bottom. Too little and you get wrinkles. On a servo press, I program a decreasing blank holder force through the stroke —start at 35% of draw force and reduce to 20% as the cup deepens. This follows the material's work hardening curve.

yuki_rd

The draw ratio limit for 304 SS is about 2.0 for the first draw (blank diameter / punch diameter). For deeper cookware like stockpots, you need multiple draws with intermediate annealing. The servo press advantage: you can do a partial draw and redraw in the same stroke using a compound die with the right motion profile. Eliminates one press operation.

mchen_servo

We run 304 and 430 SS cookware on two Aida servo presses. Biggest lesson learned: lubricant makes or breaks the job. We switched from chlorinated draw compound to a polymer-based film (Irmco Fluoprotec 9) and our reject rate dropped from 8% to under 2%. The chlorinated stuff was breaking down at the temperatures we were hitting in the deeper draws.

Die temperature management is critical too. 304 SS generates a lot of heat during forming — we run coolant channels in the draw ring and keep the die surface under 60C. Above that, galling starts and you're re-polishing the die every 5000 hits instead of every 50000.

For the servo motion profile: slow approach (50mm/s), then ramp down to 15-20mm/s through the draw zone, dwell 0.3s at BDC for the material to relax, then fast return. The dwell is the secret — reduces springback by about 30% on our 2mm wall pots.