• Material: Self-developed NL900
• Grain Size:1.0um
• Hardness:HV4100+
• Machining: Hrc60+ hardened steel
• Design: 70% Large core diamater, 20° helix angle, 10° negative charmfer edge
• Tool Life: Up to 20 hours
The Dohre CBN corner radius end mill is designed for HRC60+ hardened steel finishing, quenched steel machining, and high-precision mold cavity finishing.
Compared with a square CBN end mill, the corner radius design reduces stress concentration at the cutting corner and helps lower the risk of edge chipping. Compared with a CBN ball nose end mill, it provides better dimensional control and higher efficiency in side-wall finishing, shoulder milling, step finishing, and flat-bottom areas with corner protection.
This tool is especially suitable for hardened mold steel, die steel, quenched steel parts, precision mold cavities, side walls, shoulders, thin-wall areas, and complex profiles where edge strength, tool life, and stable surface quality are important.
CBN is not always used to replace carbide in every machining condition. It is more suitable when the workpiece hardness, finishing allowance, machine rigidity, and cutting stability match the characteristics of CBN tools. For a broader comparison, see When Should You Use a CBN End Mill Instead of Carbide
The cutter is made from Dohre's NL900 CBN material, which is suitable for finishing hardened steel and quenched steel where ordinary carbide tools may wear quickly or lose dimensional stability.
This CBN material provides high hardness, strong wear resistance, and good thermal stability during high-hardness steel finishing. It helps the tool maintain cutting edge performance and dimensional consistency in continuous precision machining.
The tool uses a vacuum brazing process to improve bonding stability between the CBN cutting part and the tool body. Compared with ordinary brazing, vacuum brazing helps reduce oxidation, reduce insert deformation, and improve edge bonding strength.
For HRC60+ hardened steel finishing, stable CBN edge bonding is important because cutting force, heat, and vibration can directly affect tool life and surface finish.
The corner radius design helps distribute cutting stress more smoothly than a sharp square corner. This reduces the risk of corner chipping during side-wall finishing, shoulder machining, step finishing, and profile machining.
For hardened steel finishing, a CBN corner radius end mill is often a balanced choice between a square end mill and a ball nose end mill. It provides better edge protection than a square tool while maintaining better side-wall control than a ball nose tool.
For users comparing different CBN tool shapes, this guide explains the difference more clearly: CBN End Mill for Hardened Steel: Square vs Ball Nose vs Corner Radius.
The tool adopts a reinforced geometry design for stable machining of high-hardness materials.
Key geometry features include:
• 70% large core diameter for higher rigidity
• 20° helix angle for stable cutting and smoother machining
• Negative chamfer edge to strengthen the cutting edge
• 4-flute structure for stable finishing performance
• Dedicated CBN grinding process for precise edge forming
This structure is designed for finishing and semi-finishing rather than heavy roughing. It is more suitable for stable cutting conditions where edge strength, surface quality, and dimensional accuracy are important.
The combination of NL900 CBN material, vacuum brazing, reinforced core, and negative chamfer edge helps improve tool life and batch finishing stability under suitable machining conditions.
Tool life is affected by workpiece hardness, finishing allowance, cutting parameters, machine rigidity, tool overhang, runout, clamping condition, and toolpath stability. When chipping or rapid wear happens too early, it is often caused by unstable cutting conditions or incorrect tool application. More details are explained in Why Do CBN End Mills Chip or Wear Quickly? Causes and Solutions
Dohre CBN corner radius end mills are mainly used for precision finishing of HRC60+ hardened steel, quenched steel, and high-hardness mold materials.
| Machining Need | Why Choose CBN Corner Radius End Mill |
|---|---|
| Side-wall finishing | Better edge protection and stable dimensional control |
| Shoulder finishing | Corner radius reduces stress concentration at the cutting edge |
| Step machining | Stronger corner design helps reduce chipping risk |
| Profile finishing | Supports stable finishing of complex hardened steel profiles |
| Mold cavity finishing | Suitable for precision finishing of hardened mold cavities |
| Thin-wall finishing | Reinforced structure helps reduce vibration and edge damage |
| Deep cavity finishing | Corner protection improves stability under longer reach conditions |
| Batch finishing | CBN material helps maintain tool life and dimensional consistency |
Suitable workpiece materials include:
• HRC60+ hardened steel
• Quenched steel
• Hardened mold steel
• High-hardness die steel
• Heat-treated steel parts
• Precision mold cavities
• Hardened inserts and small precision mold components
CBN tool selection should not depend only on the material name. The actual workpiece hardness, machining allowance, setup rigidity, and finishing requirement should also be considered. For more details, see What Hardness Range Is Suitable for a CBN End Mill?
For users machining quenched steel parts, this selection guide may also help: CBN End Mill for Quenched Steel: How to Choose the Right Tool
Dohre focuses on CBN tool manufacturing, precision grinding, vacuum brazing, radius accuracy, edge consistency, and final inspection. For CBN corner radius end mills, stable manufacturing quality is especially important because small edge defects can directly affect tool life, surface finish, and dimensional accuracy in hardened steel finishing.
CBN tools require dedicated grinding processes and grinding wheels. Dohre uses precision grinding equipment and CBN-specific grinding methods to maintain edge sharpness, geometry consistency, and stable tool quality.
CBN end mills are produced using German Walter 5-axis high-precision grinding machines. This helps maintain accurate flute geometry, stable tool dimensions, and repeatable cutting edge quality.
For CBN corner radius end mills, R-angle grinding accuracy can be controlled within 0.003–0.005 mm. This helps improve corner consistency, profile accuracy, and surface stability in precision mold finishing.
Tool profile and key dimensions are inspected using Walter HELICHECK PLUS measuring equipment. This helps ensure stable geometry and consistent batch quality.
CBN cutting edges are inspected under high magnification to check edge condition, micro-chipping, cracks, serration, and other visible defects before delivery.
From NL900 CBN material selection to vacuum brazing, precision grinding, edge inspection, and final quality control, Dohre follows strict procedures to support stable tool performance for hardened steel finishing and OEM CBN tool orders.
Q1: What is a CBN corner radius end mill used for?
A CBN corner radius end mill is mainly used for finishing HRC60+ hardened steel, quenched steel, mold cavities, side walls, shoulders, steps, and precision profiles where edge strength and stable surface quality are important.
Q2: When should I choose a CBN corner radius end mill instead of a CBN square end mill?
Choose a CBN corner radius end mill when the sharp corner of a square end mill is easy to chip, or when side-wall, shoulder, step, and profile finishing require stronger edge protection.
Q3: When should I choose a CBN ball nose end mill instead?
A CBN ball nose end mill is more suitable for 3D surfaces, curved profiles, freeform contours, and mold surfaces where the tool contact angle changes continuously.
Q4: Is this CBN corner radius end mill suitable for roughing?
It is mainly recommended for finishing and semi-finishing. CBN tools perform better in stable cutting conditions. Heavy roughing, excessive interrupted cutting, or unstable engagement can increase the risk of edge chipping.
Q5: What hardness range is suitable for this tool?
This tool is mainly designed for HRC60+ hardened steel and quenched steel finishing. Actual suitability also depends on machine rigidity, tool holding, cutting parameters, and toolpath stability.
Q6: Why does a CBN end mill chip during hardened steel machining?
Common reasons include wrong hardness range, unstable tool engagement, excessive runout, long overhang, weak clamping, unsuitable tool geometry, or aggressive cutting parameters.
Q7: Can Dohre customize CBN corner radius end mills?
Yes. Dohre supports custom CBN corner radius end mills, including diameter, corner radius, effective length, overall length, shank size, flute structure, and application-specific geometry.
Q8: Are you a CBN corner radius end mill manufacturer?
Yes. Dohre manufactures CBN end mills for hardened steel and quenched steel finishing, including CBN flat end mills, CBN ball nose end mills, and CBN corner radius end mills.
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