HEX Ball Nose End Mill for Hardened Steel HRC60–68

HEX ball nose end mills are specially developed for hardened steel machining from HRC60 to HRC68. They are designed for 3D contouring, curved surface machining, mold cavity finishing, and precision finishing of high-hardness mold components.

Compared with general-purpose ball nose end mills, the HEX series provides stronger edge support, better wear resistance, and more stable cutting performance in high-hardness machining. Its ultra-fine carbide substrate, DR3 high-wear-resistant coating, precise R-angle grinding, and negative rake geometry help improve tool life, surface quality, and dimensional accuracy.

This tool is especially suitable for finishing and semi-finishing of hardened mold steels such as H13, 718H, NAK80, S136, and similar high-hardness mold materials.

                                                                                          Standard Size List

Dohre HEX series ball nose end mill is available in a wide range of standard sizes, covering ball radius from R0.5 to R12.5, cutting diameter from 2 mm to 40 mm, shank diameter from 3 mm to 25 mm, and overall length up to 100 mm.

This complete size range allows machinists to choose the right tool for both small, high-precision mold details and large cavity finishing. Smaller radius tools such as R0.5–R2 are ideal for fine contour and detail machining, while larger sizes up to R12.5 provide higher efficiency and stability in large surface and cavity finishing operations.

1. Material – Ultra-Fine Carbide for HRC60–68 Machining

Dohre HEX ball nose end mills are manufactured from ultra-fine carbide with an average grain size of 0.4 μm and 9% cobalt content.

This carbide substrate provides:

•High hardness for machining hardened steel from HRC60 to HRC68

•Excellent wear resistance for long-cycle finishing

•Good toughness and edge strength to reduce micro-chipping

•Stable cutting performance in continuous finishing operations

Compared with conventional carbide, the ultra-fine grain substrate offers better wear resistance while maintaining sufficient toughness, making it especially suitable for high-hardness mold steels.

2. Coating – DR3 High-Wear-Resistant Coating

The cutting tool uses DR3 high-wear-resistant coating, specially developed for hardened steel and high-hardness mold steel machining.

Coating advantages include:

• •Heat resistance up to 1300°C

• •Improved oxidation resistance under high cutting temperatures

• •Lower friction to reduce cutting heat and support smoother chip evacuation

• •Better wear resistance for semi-finishing and finishing applications

This coating helps extend tool life and maintain consistent surface quality when machining hardened steel at high spindle speeds.

3. Design Features – Geometry Optimized for Hardened Steel Finishing

Dohre HEX ball nose end mills adopt a reinforced geometry design for precision finishing of hardened steel.

Key design features include:

• •Large core diameter design up to 68% for better rigidity and vibration resistance

• •0° to -5° negative rake angle for stronger edge support and reduced micro-chipping

• •35° helix angle for smooth cutting action and stable tool engagement

• •Precise ball nose geometry for 3D contouring and mold cavity finishing

4. Precision Ball Nose Accuracy

For HEX ball nose tools, the R-angle grinding accuracy can be controlled within 0.003–0.005 mm.

This helps improve:

• •Contour accuracy

• •Surface consistency

• •Mold cavity finishing quality

• •Dimensional stability during precision machining

Accurate ball nose geometry is especially important for hardened mold finishing, where surface transitions and profile accuracy directly affect the final machining result.

5. Application Range

Dohre HEX ball nose end mills are suitable for machining high-hardness materials from HRC60 to HRC68, including:

• • H13

• • 718H

• • NAK80

• • S136

• • Other hardened mold and die steels

They are widely used in:

• • Mold cavity finishing

• • 3D surface machining

• • Curved surface finishing

• • Complex contour and profile finishing

• • High-precision mold and die manufacturing

Recommended Application Guide

Size Range Overview

Detailed dimensions can be listed in the specification table according to standard and customized models.

Dohre CNC focuses on precision grinding, edge consistency, and strict inspection for high-hardness machining tools. HEX series ball nose end mills are produced under controlled manufacturing processes to ensure stable tool geometry and reliable batch quality.

German Walter 5-Axis Grinding Machines

HEX ball nose end mills are produced using German Walter 5-axis high-precision grinding machines. This helps maintain accurate flute geometry, sharp cutting edges, and stable dimensional consistency, making cutting smoother and more stable in hardened steel machining.

For HEX ball nose tools, R-angle grinding accuracy can be controlled within 0.003–0.005 mm, helping ensure better contour accuracy and more consistent surface quality.

Edge Preparation and Passivation

The cutting edges are treated by a fully automatic passivation machine using rubber-bonded diamond abrasive polishing. This process helps ensure consistent edge quality across all tools, with the passivation value controlled within ±3 μm.

For hardened steel machining, consistent edge preparation is especially important because unstable edge quality can lead to micro-chipping, poor surface finish, and shortened tool life.

Precision Inspection

Tool profile, R-angle accuracy, and cutting edge quality are inspected using precision measuring equipment, including Walter HELICHECK PLUS and high-magnification optical inspection. This helps ensure stable geometry, reliable edge quality, and consistent batch production.

Stable Batch Quality

From carbide material selection to grinding, coating, edge preparation, and final inspection, Dohre follows strict quality control procedures to support consistent performance for standard products and OEM orders.

Q1: What is the HEX ball nose end mill mainly used for?

The HEX ball nose end mill is mainly used for hardened steel machining from HRC60 to HRC68. It is suitable for 3D contour milling, curved surface machining, mold cavity finishing, and precision finishing of high-hardness mold components.

Q2: What materials can this tool machine?

It is designed for hardened steel and high-hardness mold materials such as H13, 718H, NAK80, S136, and similar mold steels within the recommended HRC60–68 range.

Q3: Why use a ball nose end mill for hardened steel finishing?

A ball nose end mill is suitable for 3D surfaces, curved profiles, and mold cavities. It helps create smoother surface transitions and better finishing quality compared with square end mills in complex contour machining.

Q4: What is the advantage of R-angle accuracy?

Accurate R-angle grinding helps improve contour precision and surface consistency during mold finishing. HEX ball nose tools can achieve R-angle grinding accuracy within 0.003–0.005 mm.

Q5: Why does the tool use a negative rake angle?

The 0° to -5° negative rake angle helps strengthen the cutting edge and reduce micro-chipping. This is important for high-hardness steel machining, where edge durability is critical.

Q6: Can HEX ball nose end mills be customized?

Yes. Dohre can provide customized HEX ball nose end mills based on diameter, flute length, overall length, R size, shank size, coating, and special geometry requirements.

Get In Touch

Need a ball nose end mill for hardened steel machining?

Contact Dohre for HEX end mill selection, OEM customization, and quotation support for HRC60–68 applications.