Automotive transmission coupling gears require reliable final finishing after carburizing and hardening. For a 16MnCr5 gear application at HRC 58–62, UHD applied its Composite Brazed CBN Insert Series to address tool marks, dimensional variation, and frequent tool changes during continuous dry finishing. The solution combined a composite brazed CBN insert structure with application-focused geometry and cutting-parameter optimization for stable automated production.
Transmission coupling gears are critical drivetrain components. Their final dimensions, surface condition, and part-to-part consistency directly affect downstream assembly and quality control. After carburizing and hardening, the material in this application reached HRC 58–62, requiring small-allowance finishing of the internal bore and end face.
The operation was deployed on automated CNC turning equipment or linked production lines, where cutting stability matters beyond individual insert performance. A predictable insert life, controlled wear behavior, and consistent dimensional output help maintain production rhythm while reducing manual intervention.
Small-allowance cutting could produce visible tool marks that affected surface quality requirements.
As machining continued, size fluctuation became more noticeable and made batch consistency harder to maintain.
Limited edge life increased tool-change frequency and interrupted the intended production cycle.
Less predictable tool behavior added maintenance pressure in an automated machining environment.
| Industry | Automotive components |
|---|---|
| Workpiece | Automotive transmission coupling gear |
| Material and hardness | 16MnCr5, carburized and hardened to HRC 58–62 |
| Machining area | Internal bore and end face |
| Operation | Continuous cutting, finishing |
| CBN insert | UHD UPN605 C06, VBGW160404 composite brazed CBN insert |
| Cutting environment | Dry cutting |
In this application, the UHD solution was compared with the previously used Japanese and Korean brand CBN inserts under the same machining conditions. The recorded results showed improvements in cutting speed, cycle time, and insert life.
| Performance Item | Previous CBN Insert | UHD UPN605 C06 | Observed Change |
|---|---|---|---|
| Cutting speed | 140 m/min | 160 m/min | Increase of 20 m/min |
| Machining time per part | 4 seconds | 3 seconds | Approximately 25% shorter |
| Tool life per cutting edge | 50 parts/edge | 250 parts/edge | Approximately 400% increase |
During continuous production, tool marks were visibly reduced, dimensional variation became more controlled, and lower insert-change frequency helped reduce machine downtime.
For automated gear finishing, an insert must support more than a single successful cutting cycle. Consistent edge quality and stable wear behavior can help manufacturers plan tool changes, preserve machining rhythm, and reduce unexpected intervention. This is particularly relevant in multi-station and unattended production environments.
This application demonstrates a practical route for continuous, small-allowance finishing of hardened steel components. The approach may be relevant for automotive gears, bearings, wind-power transmission components, and other parts with similar material hardness and finishing requirements.
Final insert selection should be based on the workpiece material, hardness range, interrupted or continuous cutting condition, machining allowance, machine rigidity, dimensional requirement, and target surface condition. UHD supports non-standard tool development and application coordination for specific machining conditions.
Henan UHD Ultrahard Tools Co., Ltd combines composite brazed CBN insert design, controlled manufacturing, and machining application support to help manufacturers address hardened steel finishing requirements. For transmission gear finishing and other high-hardness precision cutting operations, UHD focuses on matching the cutting tool to the actual production condition for stable, repeatable performance.
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