HH(300) 2 flute micro carbide square end mill with 0.3μm ultra-fine carbide and TiSiN PVD coating for high-speed, dry and semi-dry machining of hardened steel and mold steel up to 60 HRC.
The HH(300) 2 flute micro end mill is developed for precision machining of hardened steel and mold steel where a small cutting diameter and high thermal resistance are required.
Its 0.3μm ultra-fine carbide substrate is combined with a high-performance TiSiN PVD coating and dedicated cutting geometry for demanding high-speed applications. The tool is intended for hardened steel up to 60 HRC, with dry and semi-dry machining as key application modes. It can also be used for titanium alloys and nickel-based high-temperature alloys under suitable cutting conditions.
Product Highlights
Micro Milling Hardened Steel
Small-diameter tools are often used for fine features, narrow areas and precision mold components. When the workpiece is hardened, the combination of tool size, cutting temperature and edge wear becomes more demanding.
The HH(300) is positioned specifically for this combination.
Small Features in Hardened Steel
The micro square-end configuration is suitable for small pockets, narrow walls, fine steps and other precision features where a standard-size end mill is too large.
Mold and Die Components
The tool is suited to hardened mold steels where dimensional accuracy and edge stability are important.
Hardened Steel up to 60 HRC
The stated application range extends to hardened steel up to 60 HRC, making the HH(300) suitable for high-hardness machining under controlled cutting conditions.
Why TiSiN Suits This Application
High-Temperature Resistance
High-speed milling of hardened steel generates substantial cutting heat. TiSiN is selected for applications requiring resistance to elevated temperatures and thermal oxidation.
Hot Hardness
The coating is designed to retain high hardness characteristics under elevated cutting temperatures, supporting edge protection during demanding machining.
Wear Protection
The TiSiN coating works with the ultra-fine carbide substrate to provide resistance against the wear mechanisms encountered in hardened-steel milling.
Dry and Semi-Dry Machining
The HH(300) is particularly suited to dry and semi-dry cutting, reducing dependence on conventional flood coolant where the machining setup permits it.
The supplied product data specifies high-temperature resistance up to approximately 1200°C for the coating system. This should not be interpreted as an actual cutting temperature.
TiSiN-coated 2-flute carbide square end mills are commercially positioned for hardened-steel applications, with fine-grain carbide and thermal resistance commonly emphasized for high-speed machining.
What the 2-Flute Design Offers
Open Flute Space
A 2-flute layout provides more open flute space around the cutting zone, which is useful when chip evacuation becomes important in small-diameter machining.
Suitable for Micro Tools
The configuration is well suited to micro-diameter cutters where restricted chip space can quickly affect machining stability.
Precision Cutting
Two cutting edges allow the tool to be used in controlled micro-milling operations where cutting engagement must be carefully managed.
This product structure is consistent with commercial micro end mill offerings that use 2 flutes and square-end geometry for steel, stainless steel, non-ferrous materials and hardened materials.
Material Applications
Hardened Steel
The primary application for the HH(300). Suitable for hardened steels up to 60 HRC when tool diameter, machine rigidity and cutting conditions are properly matched.
Mold Steel
Suitable for precision mold and die components where small features need to be machined after hardening.
Titanium Alloys
Applicable to selected titanium machining operations where cutting heat and tool wear require careful control.
Nickel-Based High-Temperature Alloys
Suitable for selected high-temperature alloy applications under appropriate cutting conditions.
Material Compatibility
| Workpiece Material | Application Focus |
| Hardened Steel ≤60 HRC | Precision micro milling |
| Mold Steel | Fine features and mold components |
| Titanium Alloy | Difficult-material micro machining |
| Nickel-Based High-Temperature Alloy | High-temperature alloy machining |
| Other Difficult Materials | Application dependent |
Final tool selection should consider material grade, hardness, tool diameter, machine rigidity, spindle performance, tool overhang and cutting conditions.
0.3μm Ultra-Fine Carbide
The 0.3μm ultra-fine grain carbide substrate is a key part of the HH(300)’s design.
The fine grain structure supports:
For micro machining, substrate performance becomes increasingly important because the cutting edge has less physical margin for wear or damage.
Tool Geometry for Micro Machining
The HH(300) uses a dedicated geometry intended for high-speed machining of difficult materials.
The geometry is designed around:
The result is a tool configuration intended specifically for precision machining of hardened materials, rather than a conventional general-purpose end mill simply reduced in diameter.
Technical Specifications
| Parameter | Specification |
| Series | HH(300) |
| Tool Type | 2 Flute Micro Carbide Square End Mill |
| Flute Count | 2 |
| End Type | Square |
| 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 |
| Recommended Materials | Hardened Steel, Mold Steel, Titanium Alloy, Nickel-Based Alloys |
Size Information
For micro end mills, the cutting diameter should be considered together with the flute length, shank diameter and overall length.
Important dimensions include:
How to Choose the HH(300)
Start With the Feature Size
Identify the narrowest feature that needs to be machined before choosing the cutting diameter.
Check the Workpiece Hardness
For hardened steel, confirm that the workpiece falls within the 60 HRC application range.
Consider Cutting Depth
Select the appropriate flute length according to the actual feature depth. Avoid unnecessary tool extension.
Check Machine Rigidity
Micro tools are sensitive to spindle runout, vibration and toolholding accuracy. A rigid setup is important for stable results.
Choose the Cutting Environment
For high-speed applications, decide whether dry, semi-dry or coolant-assisted machining is appropriate for the specific workpiece and machine.
Cutting Conditions
Micro machining of hardened steel requires carefully controlled cutting conditions.
Recommended data can be provided for:
For an accurate recommendation, provide:
Tool Diameter + Material Grade + Hardness + Machining Depth + Machine Conditions
Dry and semi-dry machining can generate significant heat. Cutting parameters should be validated for the actual tool diameter and workpiece condition rather than copied from standard-size end mills.
Custom Micro End Mills
Need a special diameter, flute length or tool configuration?
JimmyTool can manufacture customized micro carbide end mills according to your machining requirements and technical drawings.
Custom Options
Frequently Asked Questions
What is the HH(300) 2 flute micro end mill mainly used for?
The HH(300) is primarily designed for small-feature machining of hardened steel and mold steel, with an application range up to 60 HRC.
Can the HH(300) machine 60 HRC steel?
Yes. The stated application range is up to 60 HRC, provided the tool configuration and cutting conditions are appropriate.
Why is TiSiN used for hardened steel?
TiSiN is suited to demanding thermal and wear conditions, making it a suitable coating choice for high-speed machining of hardened materials.
Is the HH(300) designed for dry cutting?
Yes. Dry and semi-dry machining are key application modes for the HH(300).
