For automotive driven gears manufactured from carburized and hardened 20CrMnTiH steel at HRC58–62, finishing performance depends on more than achieving the target cycle time. Surface consistency, dimensional control, predictable wear, and reduced intervention are all important in automated production.
UHD developed the UPN605 Composite Brazed CBN Insert as a practical replacement solution for ceramic inserts in small-allowance hardened steel gear finishing. Under unchanged machine settings and cutting parameters, the insert increased observed tool life from 150 to 1,000 parts per cutting edge, while supporting more stable surface and dimensional results.
Driven gears are load-bearing components within automotive transmission systems. Their finishing process must support demanding requirements for size accuracy, surface condition, and repeatability across production batches. After carburizing and quenching, 20CrMnTiH becomes a typical hardened steel machining material, requiring a tool strategy that remains reliable through long production runs.
In this application, the existing ceramic insert process could meet the basic production rhythm, but the small finishing allowance of approximately 0.07 mm exposed several process-control limitations:
Rather than changing equipment or increasing cutting speed, UHD focused on improving stability within the customer’s established process window. The UPN605 solution was designed for consistent small-allowance finishing and mild interrupted cutting conditions on hardened steel gear features.
A CBN composite layer combined with a carbide substrate balances wear resistance and impact resistance for the application’s light interrupted-cutting conditions.
The cutting edge and tool-tip configuration were optimized for finishing allowances below 0.2 mm, with attention to stable cutting behavior and chip evacuation.
Precision brazing supports geometric consistency between inserts, helping reduce variation associated with tool setup and long-cycle machining.
The validation used an equal-parameter replacement method. Maintaining the original equipment and cutting conditions allowed the production team to compare insert performance without introducing additional variables or disrupting the existing cycle time.
| Process item | Application condition |
|---|---|
| Workpiece | Automotive driven gear, 20CrMnTiH, HRC58–62 |
| Machining operation | Face and outer-diameter finishing with light interrupted cutting |
| Insert | UHD UPN605 Composite Brazed CBN Insert, CNGA120408 |
| Cutting environment | Dry cutting |
| Cutting speed (Vc) | 130 m/min |
| Depth of cut (ap) | 0.07 mm |
| Feed rate (f) | 0.08 mm/rev |
| Evaluation item | Previous ceramic insert | UHD UPN605 CBN insert |
|---|---|---|
| Production cycle time | 12 seconds per part | 12 seconds per part |
| Tool life per cutting edge | Approximately 150 parts | Approximately 1,000 parts |
| Surface condition | Noticeable tool marks and variation | Tool marks were reduced; surface consistency improved |
| Dimensional behavior | Wear-related drift during production | Reduced dimensional drift over longer runs |
| Line intervention | More frequent insert changes | Fewer changeovers and less interruption |
Result context: The reported life increase—from 150 to 1,000 parts per cutting edge, or approximately 570%—was achieved in this specific driven gear finishing application under the stated conditions. Actual results may vary with workpiece condition, machine rigidity, setup, and cutting parameters.
For hardened steel gear finishing, a CBN insert should not be treated as a simple material substitution. Its value lies in how the cutting material, brazed structure, edge preparation, and application conditions work together to make the process more controllable.
The UHD Composite Brazed CBN Insert approach is relevant when the production objective is stable precision finishing rather than a change in machine capability or cycle-time strategy. It may be considered for:
For manufacturers evaluating a CBN insert replacing a ceramic insert, an equal-parameter trial provides a direct basis for assessment. Keeping the existing machine, cycle time, cutting speed, depth of cut, and feed rate unchanged makes it easier to evaluate tool life, surface condition, dimensional stability, and operator intervention under real production conditions.
In small-allowance hardened steel finishing, the most useful tool improvement is often not higher speed—it is a more consistent process over a longer, more predictable cutting-edge life.
Henan UHD Ultrahard Tools Co., Ltd. (UHD) supports CBN and PCD cutting-tool applications for precision metal cutting, including Composite Brazed CBN Inserts, formed tools, and non-standard tool solutions. For hardened gear finishing projects, UHD can work from the material condition, component geometry, allowance, cutting path, machine setup, and target process requirements to support appropriate insert selection and application validation.
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