CBN Insert Solution for High-Consistency Finish Machining of Hardened Automotive Driven Gears

Automotive Components · Hardened Steel Finish Machining

Performance Comparison Under Identical Parameters

Tool life increased by approximately 570%. The machining cycle and cutting speed remained unchanged.

Project Background and Challenge

The driven gear is a load-bearing component in an automotive transmission system. After carburizing and hardening, the 20CrMnTiH workpiece requires stable finishing to maintain dimensional accuracy and surface quality across production batches. The existing ceramic insert process met the required cycle time, but its small-allowance cutting performance at approximately 0.07 mm was affected by visible tool marks, dimensional drift after wear, and frequent insert changes.

CBN Insert Strategy

UHD developed an equal-parameter replacement approach using the UPN605 composite brazed CBN insert. Its CBN cutting layer and carbide substrate were selected to balance wear resistance with impact tolerance during light interrupted cutting. The insert geometry, cutting edge treatment, and brazed structure were optimized for finish machining with less than 0.2 mm allowance, supporting stable cutting on the gear face and outer diameter without changing the customer’s equipment or established cycle settings.

Process Improvements Observed

• Surface tool marks were reduced, with more consistent finish quality during the tool life cycle.
• Dimensional variation was better controlled during extended continuous machining.
• Lower insert-change frequency reduced manual intervention and production interruptions.
• More predictable tool performance supported stable operation on the automated line.

Application Value

This automotive driven gear case shows that CBN insert selection for hardened steel finishing should be evaluated beyond cutting speed alone. For small-allowance precision turning, a controlled equal-parameter validation can provide a practical route to compare ceramic insert replacement options. By improving wear stability, part-to-part consistency, and tool-change intervals, the UHD UPN605 solution created a more reliable process foundation for automated hardened gear machining and similar transmission-component applications.