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

Medical device stamping precision requirements on servo

tony_servo

We stamp medical device components and the validation requirements are intense. Here's what we've learned about running these jobs on a servo press.

**Why Medical Stamping Is Different
**
Medical device components (surgical instrument parts, implant components, catheter fittings) require tolerances and traceability that exceed typical industrial stamping.

**Typical Requirements
**
- Dimensional tolerance: +/-0.005-0.02mm on critical features
- Surface finish: Ra 0.4-0.8 μm (no burrs, no scratches)
- Material: 316L stainless steel, titanium, cobalt-chrome alloys
- Traceability: every part must be traceable to material lot and press parameters
- Validation: IQ/OQ/PQ required for FDA-regulated devices

**Press Requirements
**
To achieve +/-0.005mm tolerances:
- BDC repeatability: +/-0.002mm or better
- Slide parallelism: 0.003mm per 300mm
- Temperature-compensated position control (thermal expansion affects accuracy)
- Direct-drive servo press only (gear reducers introduce backlash)

**Process Control**

**100% tonnage monitoring:** Every stroke must be within +/-3% of nominal. Out-of-tolerance strokes trigger automatic part rejection.

**Parameter logging:** Press must log slide position, velocity, and tonnage for every stroke. Data retained for device lifetime (typically 10+ years).

**Die qualification:** New dies require 300-stroke qualification run before production. Statistical analysis of all 300 strokes.

**Recommended Presses
**
For medical stamping at 10-50T:
- Aida DSF-N1 series (direct drive, +/-0.002mm BDC)
- Bruderer BSTA (high-speed, excellent for small parts)

For 50-200T medical components:
- Aida DSF-N1-200
- Schuler MSP series

lisaQ_metrology

Medical stamping validation is a different world. We run IQ/OQ/PQ protocols on every new die setup. The servo press force monitoring data is essential for the PQ —we need to demonstrate CPK > 1.67 on all critical dimensions over a 1000-piece validation run. Without the servo's data logging, this would require 100% CMM inspection.

sarahJ_mfg

Traceability is the big one. Every part needs to be traceable to the specific press stroke that made it. We use the press controller's stroke counter synced with a vision system that reads the part serial number. If a quality issue is found downstream, we can pull the exact force curve for that specific part.

mchen_servo

We do Class III implant components (spinal screws and plates) so I can add some specifics on what the FDA auditors actually look at.

The CPK 1.67 requirement is the minimum — our customer specs call for 2.0 on critical-to-function dimensions. The servo press force data is half the story. The other half is correlating force curve features to actual dimensional outcomes. We ran a DOE with 5 force levels x 3 speeds x 2 lube conditions and built a regression model. Now we can predict dimensional drift from the force curve alone without pulling parts for measurement. That model is what got us through our last FDA audit — they loved that we could demonstrate real-time process control, not just post-hoc inspection.

On traceability — we went beyond stroke counter sync. Each part gets a 2D Data Matrix laser-marked within 3 seconds of forming (inline station after the press). The mark encodes: press ID, die ID, stroke number, date/time, and a hash of the force curve peak/integral. If a surgeon reports an issue with an implant 10 years from now, we can pull the exact forming conditions. Cost us about $45K for the marking station but it's non-negotiable for Class III.

Biggest lesson: your validation protocol needs to include the press thermal state. We failed an OQ run because we started stamping immediately after a die change. The press frame hadn't reached thermal equilibrium and BDC was drifting for the first 200 parts. Now our SOP requires 15 minutes of dry cycling before any validation run starts.