HH(300) 4 flute carbide corner radius end mill with 0.3μm ultra-fine carbide and TiSiN PVD coating for high-speed machining of hardened and mold steels up to 60 HRC.
The HH(300) 4 flute corner radius end mill is designed for high-speed milling of hardened and mold steels where cutting-edge support is critical.
Its rounded corner geometry provides a reinforced transition between the end and side cutting edges, making it suitable for pocket, shoulder and profile machining. A 0.3μm ultra-fine carbide substrate combined with a TiSiN PVD coating supports high-temperature cutting and wear resistance in hardened steel applications up to 60 HRC.
The tool is particularly suited to high-speed, dry and semi-dry machining and can also be used for selected titanium alloy and nickel-based high-temperature alloy applications.
Product Highlights
Corner Radius for Hardened-Steel Milling
The main functional difference from a square end mill is the geometry at the cutting corner.
Reinforced Cutting Edge
The rounded transition provides more material behind the cutting corner than a sharp 90° edge, helping the tool withstand concentrated cutting loads.
Reduced Corner Damage
Corner radius geometry can reduce the tendency for localized corner chipping during hard milling and interrupted engagement. This is a common reason commercial TiSiN corner-radius tools are positioned for hardened-steel shoulder and pocket operations.
Stable Pocket and Shoulder Milling
The geometry is suited to machining pockets, shoulders and profiles where both the end and side cutting edges are engaged.
Useful for Mold Features
The rounded corner is well suited to hardened mold and die machining where edge durability and controlled transitions are important.
Hard Milling up to 60 HRC
The HH(300) is primarily positioned for high-hardness materials rather than general-purpose steel cutting.
Hardened Steel
The stated application range reaches 60 HRC, making the tool suitable for demanding hard-milling operations.
Mold Steel
The tool is suited to hardened mold and die components where corner strength is important during pocket and profile machining.
High-Speed Cutting
The 0.3μm carbide substrate and TiSiN coating are designed for high-speed cutting conditions where heat and wear become significant.
Dry and Semi-Dry Machining
The HH(300) is particularly suitable for dry and semi-dry cutting, although coolant-assisted machining remains available when required.
TiSiN for High-Temperature Applications
The TiSiN PVD coating is the main coating technology behind the HH(300)’s hard-milling positioning.
Thermal Resistance
TiSiN is selected for demanding thermal conditions and high-temperature oxidation resistance.
Wear Protection
The hard PVD coating helps protect the ultra-fine carbide substrate during high-speed machining of hardened materials.
Dry-Cutting Compatibility
The coating system is well suited to dry and semi-dry milling where coolant use is limited or avoided.
The supplied product data specifies approximately 1200°C high-temperature performance for the coating system. This refers to coating thermal performance and should not be interpreted as an actual cutting temperature.
0.3μm Ultra-Fine Carbide
The 0.3μm ultra-fine carbide substrate provides the underlying hardness and wear resistance needed for the HH(300)’s high-hardness applications.
For a corner-radius tool, substrate performance is particularly relevant because the rounded cutting corner is designed to withstand concentrated mechanical loads.
Material Applications
| Workpiece Material | Application Focus |
| Hardened Steel ≤60 HRC | Hard milling, pocketing and profiling |
| Mold Steel | Hardened mold and die machining |
| Titanium Alloy | High-speed difficult-material machining |
| Nickel-Based High-Temperature Alloy | Selected high-temperature applications |
Actual performance depends on material grade, hardness, tool diameter, corner radius, machine rigidity, tool overhang and cutting conditions.
Technical Specifications
| Parameter | Specification |
| Series | HH(300) |
| Tool Type | 4 Flute Carbide Corner Radius End Mill |
| Flute Count | 4 |
| End Configuration | Corner Radius |
| 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 |
Corner Radius and Size Information
For this tool type, the corner radius should be evaluated together with the cutting diameter and flute length.
Key dimensions include:
Commercial 4-flute corner-radius tools likewise treat corner radius, cutting diameter and flute length as core selection parameters.
How to Select the Right Corner Radius
Match the Radius to the Part
Select the corner radius according to the required internal corner, transition or profile on the workpiece.
Consider Cutting Load
A larger radius generally provides more material behind the cutting corner and can be useful where the corner experiences concentrated loading.
Keep the Geometry Accessible
The radius must still fit the workpiece feature. An oversized radius can limit access to smaller internal corners.
Match the Radius to the Operation
Pocketing, shoulder milling, profiling and semi-finishing may call for different radius-to-diameter combinations.
Need help choosing the diameter and radius?
[Get Tool Recommendation]
Cutting Conditions
HH(300) is designed for high-speed hard milling, but the recommended parameters should be matched to the actual tool diameter, corner radius and workpiece hardness.
Cutting data can include:
The starting point should be selected according to:
Tool Diameter + Corner Radius + Workpiece Hardness + Machining Operation
Customization
Customized configurations can be considered when the standard diameter and corner-radius combinations do not match the required machining geometry.
Custom Options
Frequently Asked Questions
What is the HH(300) 4 flute corner radius end mill used for?
It is designed for pocket, shoulder and profile machining of hardened and mold steels where a reinforced cutting corner is beneficial.
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.
Why use a corner radius instead of a square end?
The rounded corner provides additional support at the cutting edge and can reduce the tendency for corner damage under concentrated cutting loads.
Is the HH(300) suitable for dry cutting?
Yes. High-speed, dry and semi-dry machining are key applications for the HH(300), while coolant-assisted machining 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.
