admin
Automotive seat frames are one of the most common servo press applications in Tier 1 and Tier 2 automotive suppliers.
## Typical Requirements
Seat frame components are typically stamped from high-strength steel (HSS) or ultra-high-strength steel (UHSS) at 590-980 MPa tensile strength:
- Dimensional tolerance: +/-0.2mm on hole positions, +/-0.5mm on overall dimensions
- No cracks or splits in the material
- Consistent springback (variation causes assembly problems)
- Typical tonnage: 100-400 tons depending on part size
## Motion Profile for HSS Seat Frame
- Approach: 400mm/s down to 20mm above material
- Pre-contact: reduce to 80mm/s at 20mm above material
- Forming: 50-100mm/s through the forming zone
- Dwell at BDC: 50-100ms (reduces springback variation)
- Return: 500mm/s
The dwell at BDC is critical for UHSS. Without dwell, springback varies by +/-0.5mm part to part. With 100ms dwell, variation drops to +/-0.1mm.
## Blank Holder Force
Starting point for blank holder force:
- HSS 590MPa: 15-20% of forming force
- HSS 780MPa: 20-25% of forming force
- UHSS 980MPa: 25-30% of forming force
If you see wrinkling in the flange area: increase blank holder force by 10% increments.
If you see splitting at the punch radius: reduce blank holder force by 10% increments.
## Lubrication for HSS
HSS and UHSS require more lubrication than mild steel due to higher forming pressures. Use draw compound with EP (extreme pressure) additives, applied at 2-4 g/m2 on both sides of the blank.
Do not use dry stamping on UHSS - the forming pressures will cause galling on the die surface within 500 strokes.
## Tonnage Monitoring
Set tonnage limits at:
- High limit: 110% of nominal (catches die crashes, double blanks)
- Low limit: 85% of nominal (catches missing blank, broken punch)