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Running a servo press for automotive structural stampings requires tight tolerances, high volumes, and zero defects.
## The Application
Part: B-pillar inner reinforcement, 1.8mm AHSS 980MPa. Annual volume: 240,000 parts. Press: 600-ton servo press, knuckle-joint drive. Die: Progressive die, 8 stations, 400mm feed pitch.
## Why Servo Was Necessary
We tried this part on a mechanical press first. Problems: springback variation of plus or minus 1.5 degrees between start and end of coil, die wear accelerating due to high impact velocity, could not hold the plus or minus 0.3mm flange height tolerance.
The servo press solved all three: springback compensation via 2 degree overbend adjustable per coil, low-impact forming at 50mm/s at contact, consistent BDC position of plus or minus 0.01mm repeatability.
## Motion Profile Development
Approach speed: 250mm/s. Forming speed: 80mm/s. Dwell at BDC: 50ms improved flange height consistency by 40%. Return speed: 600mm/s. Final cycle time: 1.8 seconds = 33 SPM.
## Production Results After 18 Months
Scrap rate: 0.08% versus 0.6% on mechanical press. Die maintenance interval: 500,000 strokes versus 150,000. Cpk on critical dimensions: 1.67 average against requirement of 1.33.