BLOG · JULY 2026
From Forging to Final Machining: How HKM3-1600 Cut Connecting Rod Machining Stock by 42%
A German automotive Tier-1 supplier approached us in early 2026 with a 42CrMo4 connecting rod — 2.1 kg finished weight, 265 mm center-to-center length — that they were forging on a competitor 1600T crank press. Excessive machining stock (1.2 mm per side) was creating a bottleneck at 45,000 rods per month.
The Machining Cost Problem
The root cause: the competitor single-toggle crank press allowed ram tilt under off-center load, creating uneven flash thickness. To guarantee cleanup after machining, the tooling designer had to add 1.2 mm stock on the thin side — which meant the CNC line was cutting through 2.4 mm of excess material on every rod. That extra 38 seconds per rod added 475 hours of CNC time per month.
Results: Before vs. After
| Metric | Competitor Crank Press | ForgePress China (HKM3-1600) |
|---|---|---|
| Machining stock per side | 1.2 mm | 0.7 mm |
| Flash thickness variation | +/-0.35 mm | +/-0.15 mm |
| Reject rate | 3.2% | 0.34% |
| Die life | 12,000 pcs | 22,000 pcs |
| CNC cycle time | 128 sec/rod | 90 sec/rod |
| Annual savings | — | EUR 1,002,000 |
The customer recouped their HKM3-1600 investment in 5.2 months from machining cost savings alone.
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