HH(300) long neck carbide corner radius end mill with 0.3μm ultra-fine carbide and TiSiN PVD coating for deep, restricted machining of hardened and mold steel up to 60 HRC.
The HH(300) long neck corner radius end mill is designed for deep and restricted machining of hardened steel and mold steel where both extended reach and a reinforced cutting corner are required.
Its long neck configuration provides additional clearance for recessed features, while the corner radius supports the cutting edge during pocket, profile and shoulder machining. The tool uses a 0.3μm ultra-fine carbide substrate with a high-performance TiSiN PVD coating, making it suitable for hardened steel up to 60 HRC and demanding high-speed, dry or semi-dry machining conditions.
Titanium alloys and nickel-based high-temperature alloys can also be machined under appropriate application conditions.
Product Highlights
Where Long Neck and Corner Radius Work Together
The two geometry features address different machining challenges.
Deep Feature Access
The long neck provides additional clearance behind the cutting section, allowing the tool to reach recessed pockets, grooves and cavities.
Corner Strength
The corner radius provides a stronger transition between the end and side cutting edges than a sharp corner, which can be useful when the tool corner experiences concentrated cutting loads.
Restricted Mold Machining
The combination is well suited to deep ribs, recessed walls, narrow pockets and other mold features where both clearance and edge support matter.
Profile and Shoulder Machining
The rounded corner supports the cutting edge during side-wall and profile operations while maintaining access to deeper features.
Long-neck corner-radius tools are commonly positioned for deep-reach, high-precision machining and hardened-steel applications. Commercial products from NS Tool and OSG use the same product category and emphasize deep reach, corner-radius accuracy, high-hardness machining and chatter control.
Hardened Steel and Mold Steel Applications
Hardened Steel up to 60 HRC
The HH(300) is designed for hardened steel applications up to 60 HRC, making it suitable for demanding hard-milling operations.
Mold Steel
The long neck configuration provides access to recessed mold features, while the corner radius is suited to transitions and profiles where a sharp corner may be more vulnerable.
Deep Cavities
The tool is suitable for deeper cavity features that require additional reach without unnecessary interference from the tool body.
High-Speed Hard Milling
The combination of fine-grain carbide and TiSiN coating supports high-speed machining under demanding thermal conditions.
TiSiN for High-Temperature Hard Milling
The TiSiN PVD coating is a key part of the HH(300)’s application in hardened materials.
Thermal Performance
The coating is designed for high-temperature cutting conditions and strong resistance to thermal oxidation.
Wear Protection
The hard PVD coating helps protect the carbide substrate during high-speed machining of hardened steel.
Dry and Semi-Dry Cutting
The HH(300) is particularly suited to dry and semi-dry machining, while coolant-assisted cutting can also be used when required by the application.
High-Hardness Applications
The coating and carbide substrate are positioned for hardened and mold-steel machining where conventional tooling can experience rapid thermal and abrasive wear.
The supplied product information specifies approximately 1200°C high-temperature performance for the coating system. This refers to coating thermal performance and should not be interpreted as the actual cutting temperature of the tool.
0.3μm Ultra-Fine Carbide
The 0.3μm ultra-fine carbide substrate provides the foundation for the HH(300)’s hard-milling performance.
Its fine grain structure is intended to support:
For long-neck tooling, maintaining sufficient substrate strength is particularly important because extended reach increases sensitivity to vibration and deflection.
Material Applications
| Workpiece Material | Application Focus |
| Hardened Steel ≤60 HRC | Deep cavities, grooves and profiles |
| Mold Steel | Recessed and precision mold features |
| Titanium Alloy | Difficult-material machining |
| Nickel-Based High-Temperature Alloy | Selected high-temperature applications |
Final performance depends on material grade, hardness, cutting diameter, corner radius, effective length, tool overhang, machine rigidity and cutting conditions.
Technical Specifications
| Parameter | Specification |
| Series | HH(300) |
| Tool Type | Long Neck Carbide Corner Radius End Mill |
| End Configuration | Corner Radius |
| Tool Design | Long Neck |
| Carbide Substrate | 0.3μm Ultra-Fine Grain Carbide |
| Coating | TiSiN PVD |
| Hardened Steel Capability | Up to 60 HRC |
| Cutting Modes | High-Speed / Dry / Semi-Dry / Coolant-Assisted |
| Recommended Materials | Hardened Steel, Mold Steel, Titanium Alloy, Nickel-Based Alloy |
Critical Dimensions
For a long-neck corner-radius tool, selection should consider the complete geometry rather than overall length alone:
Commercial long-neck corner-radius products likewise treat effective length, neck dimensions and corner-radius accuracy as important specifications for deep machining.
How to Select the Right Configuration
Determine the Machining Depth
Measure the actual feature depth before selecting the effective length.
Choose the Corner Radius
Match the radius to the required part geometry and the desired transition at the component corner.
Check Neck Clearance
Make sure the neck provides sufficient clearance from surrounding walls, ribs and shoulders.
Minimize Tool Overhang
Use the shortest practical unsupported length to reduce vibration and deflection during deep machining.
Match the Tool to the Workpiece
Confirm that the material and hardness fall within the intended HH(300) application range before selecting cutting parameters.
Cutting Conditions
The combination of long reach and corner-radius geometry makes tool setup particularly important.
Recommended cutting data can include:
The starting point should be matched to:
Tool Diameter + Corner Radius + Effective Length + Workpiece Hardness + Machining Depth
For deep hard milling, minimizing unnecessary radial engagement and tool overhang can help maintain machining stability.
Customization
Customized configurations can be considered where the standard diameter, corner radius or reach does not match the machining requirement.
Custom Options
Frequently Asked Questions
What is the HH(300) long neck corner radius end mill used for?
It is designed for deep cavities, recessed pockets, grooves, profiles and other restricted machining features in hardened and mold steels.
Can the HH(300) machine hardened steel up to 60 HRC?
Yes. The HH(300) is designed for hardened steel applications up to 60 HRC under appropriate cutting conditions.
What is the advantage of combining a long neck with a corner radius?
The long neck provides reach and clearance for deep features, while the corner radius adds support at the cutting corner during profile, pocket and shoulder machining.
Is the HH(300) suitable for dry and semi-dry cutting?
Yes. High-speed, dry and semi-dry machining are key application modes, while coolant-assisted cutting can also be used.
Can the HH(300) machine titanium alloys and nickel-based alloys?
Yes. The tool can be used for selected titanium alloy and nickel-based high-temperature alloy applications under suitable machining conditions.
