CBN Corner Radius End Mill for HRC60+ Hardened Steel Finishing

Technical data

Technical notes

• KERNVEX 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
• NL900 CBN Material for HRC60+ Machining
• The cutter is made from KERNVEX'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.
• Vacuum Brazing for Stable CBN Edge Bonding
• 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.
• Corner Radius Geometry for Stronger Edge Protection
• 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 .
• Reinforced Core and Negative Chamfer Edge
• 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.
• Stable Tool Life in Hardened Steel Finishing
• 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
• KERNVEX CBN corner radius end mills are mainly used for precision finishing of HRC60+ hardened steel, quenched steel, and high-hardness mold materials.
• 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