1. Control Interrupted Impact
Use a tougher CBN insert structure where tooth-related geometry and allowance variation create repeated edge loading.
Typical Workpiece
Driven Gear: Hard Turning After Carburizing and Quenching
This solution is designed for driven bevel gears or large gears where hardened tooth structures create periodic cutting impact. UHD separates roughing, finishing, continuous face turning, and grooving into distinct tooling tasks rather than relying on one insert for every operation.
- Material20CrMnTi carburized and quenched
- HardnessHRC60–64
- Key FeaturesLarge face, bore, spigot, root relief groove
- Production FocusBatch consistency, cycle control, process stability
Why Gear Hard Turning Requires Operation-Specific CBN Inserts
For HRC60–64 carburized gears, interrupted engagement can chip an insufficiently robust cutting edge, while bore and spigot finishing require predictable wear behavior to hold dimensions across production batches. UHD applies a three-part logic: impact resistance for roughing, stable wear performance for precision finishing, and dedicated geometry for high-risk groove machining.
2. Stabilize Critical Dimensions
Match finishing inserts to stable clamping and allowance conditions for bore, spigot, roundness, and surface consistency.
3. Isolate High-Risk Grooving
Use dedicated grooving geometry to manage concentrated cutting forces, chip evacuation, groove width, and groove-bottom quality.
CBN Insert Selection by Gear Machining Condition
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Integral Brazed CBN Insert Series — Roughing for Interrupted Cutting
Recommended for large-face rough turning and interrupted root-area roughing. It prioritizes edge strength and impact resistance to remove variable allowance more reliably before finish machining.
Coated CBN Insert — Bore and Spigot Precision Finishing
Used for high-speed hard turning or finish boring of bores and spigots under stable setup conditions. The focus is predictable wear behavior, stable surface quality, and reduced tool-change disruption in batch production.
Full Face CBN Insert Series — Large Continuous Face Turning
Suitable for large planar areas with predominantly continuous cutting. It supports wear resistance and thermal stability where accumulated heat and wear can otherwise cause size drift or surface waviness.
CBN Grooving Insert Series — Gear Root Relief Groove Machining
Designed for annular root relief grooves, where cutting force concentrates at the tool tip and chip control is critical. Dedicated geometry helps control groove width, groove bottom condition, and edge-loading risk.
A Structured Path Toward More Controlled Hardened Gear Production
- Higher process stability: Separate insert selection for interrupted, continuous, finishing, and grooving operations helps reduce single-operation instability.
- More predictable batch output: Bore and spigot finishing can be configured around stable wear behavior and controlled dimensional consistency.
- Better use of hard turning: The modular CBN strategy creates conditions for replacing part of the grinding workload where the process is suitable.
- Lower process risk: Dedicated root-grooving tooling reduces the exposure of a high-risk operation to chipping, breakage, rework, and scrap.
UHD application approach: Henan UHD Ultrahard Tools Co., Ltd evaluates material hardness, machine rigidity, workholding, allowance distribution, cooling conditions, and cycle-time targets to adapt CBN insert form and tool structure for individual gear production conditions.
