This video shows a forged steel crankshaft being straightened after heat treatment. Induction hardening and stress relieving leave the main journals and crankpins with measurable bend, and the machine locates the part on contoured supports that follow the eccentric crankpin layout instead of simple V-blocks. A traveling probe head scans runout at each main journal, the control maps the bending curve, and a hydraulic ram presses at the high points while the shaft is indexed between stations.
The closed-loop cycle measures, presses and re-measures automatically, holding total indicator runout of automotive crankshafts to 0.02–0.05 mm instead of the 0.10–0.30 mm/m typical of manual press work. Springback of hardened steel is predicted and compensated stroke by stroke — you can read how in our article on springback compensation after heat treatment. Soft contact pads protect finished journals, at cycle times of 20–90 seconds per part.
Crankshafts for passenger car, truck, construction machinery and agricultural engines all run on this setup, with changeover limited to support positions and part programs. Versus hand straightening on a floor press, the process is 5–10 times faster and one operator can run one or two CNC machines. For inspection background, see our note on TIR measurement on shafts.
To discuss your application, contact the SHANGDA engineering team with drawings and annual volume — factory visits in Tengzhou, Shandong are always welcome.
Handles post-heat-treatment bend on forged and cast crankshafts
Contoured supports follow the eccentric crankpin and journal layout
Automatic runout scan with closed-loop press-and-recheck correction
TIR held to 0.02–0.05 mm for automotive engine crankshafts
20–90 second cycles; one operator runs one or two machines
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