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End Mill for Hardened Steel 4 Flute Corner Radius End Mill

SAMHO Coated 4-Flute Corner Radius End Mill — The Ultimate Tool for High-Hardness Hardened Steel

Stop letting high-hardness materials compromise your machining efficiency and tool life. The SAMHO 4 flute corner radius end mill is engineered for high-precision CNC machining of hardened steel and other high-hardness steels. Its advanced high-adhesion coating and precision tool geometry have been proven to significantly extend tool life, maintaining stable performance even under high-load, continuous cutting conditions.

Applicable Materials: Optimized for hardened steel, high-hardness steel molds, and wear-resistant components.

Extreme Durability: Made from high-strength, ultra-fine grain carbide and precision-ground, then enhanced with a chemically inert coating. This ensures reliable operation in high-speed and heavy-load cutting environments.

High-Precision Machining: The corner radius cutting tip is ideal for internal angle transitions and complex 3D contours. It delivers smooth surfaces and consistent part dimensions, greatly improving the efficiency and quality of mold and precision part production.

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In the field of hardened steel machining, cutting tools must meet extremely high standards for precision and durability. They need to deliver fine, accurate cuts while withstanding the demands of long-term machining on high-hardness materials. SAMHO’s dedicated coated 4-flute corner radius end mills (D1R0.05–D12R1 mm) are engineered to meet these stringent requirements. These high-performance CNC end mills enable operators to efficiently and reliably machine hardened and high-hardness steels, significantly improving both machining efficiency and tool life.

Advanced Technical Features

High-Adhesion Coating for Ultra-Long Tool Life
Our proprietary composite coating technology gives these end mills exceptional hardness and chemical resistance.

  • Wear Resistance: The cutting edges stay sharp even during prolonged, continuous machining of hardened steel.
  • Micro-Chipping Prevention: Ensures the coating remains firmly bonded to the carbide substrate under high-speed, high-load cutting conditions.

Corner Radius Geometry for Complex Profile Machining
The precision-engineered corner radius tip is ideal for machining internal corner transitions and mold cavities in high-hardness hardened steel.

  • High-Precision Surface Finish: Produces smooth, burr-free surfaces on hardened steel parts.
  • Complex 3D Profiling: Perfect for high-quality machining of molds, gauges, and precision components.

High-Efficiency Four-Flute Cutting Design
The sharp four-flute geometry reduces cutting heat and improves chip evacuation.

  • Maximized Chip Evacuation: Rapidly clears chips from the cutting zone to reduce tool wear.
  • Reduced Cutting Load: Minimizes heat buildup, preventing thermal cracking in hardened steel workpieces.

Ultra-Fine Grain Carbide Substrate with Precision Grinding
Made from high-strength, ultra-fine grain carbide and precision-ground for exceptional stability and repeatable accuracy.

  • Dimensional Tolerance Control: Maintains tight tolerances within ±0.01 mm for consistent batch production.
  • Fracture Resistance: Significantly increases tool durability, ideal for machining highly abrasive, high-hardness hardened steel.

Target Applications & Industries

This series of coated 4 flute corner radius end mills is engineered for high-performance machining and is widely used for:

  • Machining mold cavities in high-hardness quenched steel.
  • Cutting precision internal corner transitions and complex 3D contours.
  • Producing high-precision molds, gauges, and critical workpieces.
  • Machining brittle or highly abrasive high-hardness steels with consistent performance.

Why Choose SAMHO as Your Wholesale Partner?

OEM/ODM Services: Provides customized CNC tooling solutions to meet diverse customer requirements.

High-Precision Shank Diameter: Maintained within 0–0.003 mm for stable tool installation and reliable accuracy.

High Performance 4 Flute Corner Radius Design: Engineered for machining high-hardness hardened steel, offering an optimal balance of efficiency and tool life.

Strict Quality Management: Every tool undergoes precision testing—from materials to coatings—to ensure consistent machining performance.

Professional Partner: Over 20 years of CNC tooling R&D experience, delivering technical support and tailored solutions.

Recommended Materials for Machining (Highly Recommended: ⭐️ | Recommended: ⭕️ | Suggested: ◯)

Category Work Material Grade
DIE STEEL Carbon steels (S45C/S55C)
Alloy steels (SK/SCM/SUS)
Prehardened steels (NAK/HPM)
Hardened steels (~55/~60/~70HRC) ⭐️
SPECIAL MATERIAL Aluminum alloys
Graphite
Copper
Plastics
Carbon fiber
Titanium alloys
Heat resistant alloys
Cemented carbide
Hard brittle (non-metallic) material

4 flute end mill

Total 72 models

Model Number Outside Diameter Radius Length Of Cut Effective Length Shank Taper Angle Overall Length Number Of Flutes Shank Diameter In Stock
SHHSR4-010005030 1 R0.05 1 3 12° 50 4 4 ○
SHHSR4-01001030 1 R0.1 1 3 12° 50 4 4 ○
SHHSR4-01002030 1 R0.2 1 3 12° 50 4 4 ○
SHHSR4-01501045 1.5 R0.1 1.5 4.5 12° 50 4 4 ○
SHHSR4-01502045 1.5 R0.2 1.5 4.5 12° 50 4 4 ○
SHHSR4-02001060 2 R0.1 2 6 12° 50 4 4 ○
SHHSR4-02002060 2 R0.2 2 6 12° 50 4 4 ○
SHHSR4-02003060 2 R0.3 2 6 12° 50 4 4 ○
SHHSR4-02005060 2 R0.5 2 6 12° 50 4 4 ○
SHHSR4-03001090 3 R0.1 3 9 12° 50 4 4 ○
SHHSR4-03002090-3 3 R0.2 3 9 12° 50 4 4 ○
SHHSR4-03002090 3 R0.2 3 9 12° 50 4 4 ○
SHHSR4-03003090 3 R0.3 3 9 12° 50 4 4 ○
SHHSR4-03005090-3 3 R0.5 3 9 12° 50 4 4 ○
SHHSR4-03005090 3 R0.5 3 9 12° 50 4 4 ○
SHHSR4-04001120 4 R0.1 4 12 – 50 4 4 ○
SHHSR4-04002120 4 R0.2 4 12 – 50 4 4 ○
SHHSR4-04003120 4 R0.3 4 12 – 50 4 4 ○
SHHSR4-04005120 4 R0.5 4 12 – 50 4 4 ○
SHHSR4-04005120-75 4 R0.5 4 12 – 75 4 4 ○
SHHSR4-04005120-100 4 R0.5 4 12 – 100 4 4 ○
SHHSR4-04010120 4 R1 4 12 – 50 4 4 ○
SHHSR4-04002120-6 4 R0.2 4 12 12° 60 4 6 ○
SHHSR4-04005120-6 4 R0.5 4 12 12° 60 4 6 ○
SHHSR4-05002150 5 R0.2 5 15 12° 60 4 6 ○
SHHSR4-05005150 5 R0.5 5 15 12° 60 4 6 ○
SHHSR4-06002200 6 R0.2 6 20 – 60 4 6 ○
SHHSR4-06003200 6 R0.3 6 20 – 60 4 6 ○
SHHSR4-06005200 6 R0.5 6 20 – 60 4 6 ○
SHHSR4-06010200 6 R1 6 20 – 60 4 6 ○
SHHSR4-06002200-75 6 R0.2 6 20 – 75 4 6 ○
SHHSR4-06003200-75 6 R0.3 6 20 – 75 4 6 ○
SHHSR4-06005200-75 6 R0.5 6 20 – 75 4 6 ○
SHHSR4-06010200-75 6 R1 6 20 – 75 4 6 ○
SHHSR4-06002200-100 6 R0.2 6 20 – 100 4 6 ○
SHHSR4-06003200-100 6 R0.3 6 20 – 100 4 6 ○
SHHSR4-06005200-100 6 R0.5 6 20 – 100 4 6 ○
SHHSR4-06010200-100 6 R1 6 20 – 100 4 6 ○
SHHSR4-08002240 8 R0.2 8 24 – 60 4 8 ○
SHHSR4-08003240 8 R0.3 8 24 – 60 4 8 ○
SHHSR4-08005240 8 R0.5 8 24 – 60 4 8 ○
SHHSR4-08010240 8 R1 8 24 – 60 4 8 ○
SHHSR4-08002240-75 8 R0.2 8 24 – 75 4 8 ○
SHHSR4-08003240-75 8 R0.3 8 24 – 75 4 8 ○
SHHSR4-08005240-75 8 R0.5 8 24 – 75 4 8 ○
SHHSR4-08010240-75 8 R1 8 24 – 75 4 8 ○
SHHSR4-08002240-100 8 R0.2 8 24 – 100 4 8 ○
SHHSR4-08003240-100 8 R0.3 8 24 – 100 4 8 ○
SHHSR4-08005240-100 8 R0.5 8 24 – 100 4 8 ○
SHHSR4-08010240-100 8 R1 8 24 – 100 4 8 ○
SHHSR4-08002240-150 8 R0.2 8 24 – 150 4 8 ○
SHHSR4-08003240-150 8 R0.3 8 24 – 150 4 8 ○
SHHSR4-08005240-150 8 R0.5 8 24 – 150 4 8 ○
SHHSR4-08010240-150 8 R1 8 24 – 150 4 8 ○
SHHSR4-10002300 10 R0.2 10 30 – 75 4 10 ○
SHHSR4-10005300 10 R0.5 10 30 – 75 4 10 ○
SHHSR4-10010300 10 R1 10 30 – 75 4 10 ○
SHHSR4-10002300-100 10 R0.2 10 30 – 100 4 10 ○
SHHSR4-10005300-100 10 R0.5 10 30 – 100 4 10 ○
SHHSR4-10010300-100 10 R1 10 30 – 100 4 10 ○
SHHSR4-10002300-150 10 R0.2 10 30 – 150 4 10 ○
SHHSR4-10005300-150 10 R0.5 10 30 – 150 4 10 ○
SHHSR4-10010300-150 10 R1 10 30 – 150 4 10 ○
SHHSR4-12002360 12 R0.2 12 36 – 75 4 12 ○
SHHSR4-12005360 12 R0.5 12 36 – 75 4 12 ○
SHHSR4-12010360 12 R1 12 36 – 75 4 12 ○
SHHSR4-12002360-100 12 R0.2 12 36 – 100 4 12 ○
SHHSR4-12005360-100 12 R0.5 12 36 – 100 4 12 ○
SHHSR4-12010360-100 12 R1 12 36 – 100 4 12 ○
SHHSR4-12002360-150 12 R0.2 12 36 – 150 4 12 ○
SHHSR4-12005360-150 12 R0.5 12 36 – 150 4 12 ○
SHHSR4-12010360-150 12 R1 12 36 – 150 4 12 ○

Contour Milling Parameters

Work Material HRC48-55 hardened steel HRC56-62 hardened steel HRC63-70 hardened steel
Diameter Radius (CR) (min-1) Speed (mm/min) Feed (mm) Axial depth (mm) Radidl depth (min-1) Speed (mm/min) Feed (mm) Axial depth (mm) Radidl depth (min-1) Speed (mm/min) Feed (mm) Axial depth
(mm) Radidl depth
1 R0.05 21000 1800 0.04 0.3 18000 1500 0.03 0.25 14000 1100 0.02 0.2
1 R0.1 21000 1800 0.04 0.3 18000 1500 0.03 0.25 14000 1100 0.02 0.2
1 R0.2 21000 1800 0.04 0.3 18000 1500 0.03 0.25 14000 1100 0.02 0.2
1.5 R0.1 19000 1800 0.045 0.5 16000 1500 0.03 0.4 13000 1100 0.02 0.3
1.5 R0.2 19000 1800 0.045 0.5 16000 1500 0.03 0.4 13000 1100 0.02 0.3
2 R0.1 18000 2100 0.06 0.6 15000 1800 0.05 0.5 12000 1300 0.03 0.35
2 R0.2 18000 2100 0.06 0.6 15000 1800 0.05 0.5 12000 1300 0.03 0.35
2 R0.3 18000 2100 0.06 0.6 15000 1800 0.05 0.5 12000 1300 0.03 0.35
2 R0.5 18000 2100 0.06 0.6 15000 1800 0.05 0.5 12000 1300 0.03 0.35
3 R0.1 11000 1700 0.09 0.8 9500 1400 0.06 0.7 7500 1000 0.04 0.6
3 R0.2 11000 1700 0.09 0.8 9500 1400 0.06 0.7 7500 1000 0.04 0.6
3 R0.3 11000 1700 0.09 0.8 9500 1400 0.06 0.7 7500 1000 0.04 0.6
3 R0.5 11000 1700 0.09 0.8 9500 1400 0.06 0.7 7500 1000 0.04 0.6
4 R0.1 10000 2100 0.15 1.2 8500 1800 0.08 1 7000 1300 0.06 0.8
4 R0.2 10000 2100 0.15 1.2 8500 1800 0.08 1 7000 1300 0.06 0.8
4 R0.3 10000 2100 0.15 1.2 8500 1800 0.08 1 7000 1300 0.06 0.8
4 R0.5 10000 2100 0.15 1.2 8500 1800 0.08 1 7000 1300 0.06 0.8
4 R1 10000 2100 0.15 1.2 8500 1800 0.08 1 7000 1300 0.06 0.8
5 R0.2 8000 2600 0.18 1.5 6000 2200 0.12 1.3 5000 1500 0.08 1
5 R0.5 8000 2600 0.18 1.5 6000 2200 0.12 1.3 5000 1500 0.08 1
6 R0.2 8000 2600 0.18 1.8 6000 2200 0.12 1.5 5000 1500 0.08 1.2
6 R0.3 8000 2600 0.18 1.8 6000 2200 0.12 1.5 5000 1500 0.08 1.2
6 R0.5 8000 2600 0.18 1.8 6000 2200 0.12 1.5 5000 1500 0.08 1.2
6 R1 8000 2600 0.18 1.8 6000 2200 0.12 1.5 5000 1500 0.08 1.2
8 R0.2 6000 2600 0.2 2.4 5000 2200 0.16 1.8 4000 1500 0.1 1.5
8 R0.3 6000 2600 0.2 2.4 5000 2200 0.16 1.8 4000 1500 0.1 1.5
8 R0.5 6000 2600 0.2 2.4 5000 2200 0.16 1.8 4000 1500 0.1 1.5
8 R1 6000 2600 0.2 2.4 5000 2200 0.16 1.8 4000 1500 0.1 1.5
10 R0.2 5000 2600 0.2 3 4000 2200 0.15 2.4 3000 1500 0.1 1.8
10 R0.3 5000 2600 0.2 3 4000 2200 0.15 2.4 3000 1500 0.1 1.8
10 R0.5 5000 2600 0.2 3 4000 2200 0.15 2.4 3000 1500 0.1 1.8
10 R1 5000 2600 0.2 3 4000 2200 0.15 2.4 3000 1500 0.1 1.8
12 R0.2 4000 3000 0.2 3.5 3000 2600 0.1 2.6 2000 1500 0.1 2
12 R0.3 4000 3000 0.2 3.5 3000 2600 0.1 2.6 2000 1500 0.1 2
12 R0.5 4000 3000 0.2 3.5 3000 2600 0.1 2.6 2000 1500 0.1 2
12 R1 4000 3000 0.2 3.5 3000 2600 0.1 2.6 2000 1500 0.1 2

Milling Amount for Side Milling(mm)

Work Material \ Length of Cut 2.5D (Length of Cut=Diameter*2.5) 4D (Length of Cut=Diameter*4)
45HRC以下Below 45HRC ae​=0.07Dap​=2D ae​=0.07Dap​=2D
45HRC以上Above 45HRC ae​=0.03Dap​=1.5D ae​=0.03Dap​=1.5D

D: Diameter (mm)

ap:AxialDepth (mm)

ae: Radial Depth (mm)

Note:

*Decrease both spindle speed and feed rate proportionally when the milling parameters exceed the machine’s maximum spindle speed;

*Recommend oil coolant for Stainless Steels and Heat Resistance Alloys;

*Recommend using a non-contact measuring device to avoid damaging the precisiontip point;

*Decrease both spindle speed and feed rate proportionally in case of chattering;

*When the material hardness is greater than HRC58 degrees, it is recommended to use air blow cooling for roughing andoil mistor air blow cooling for finishing.

Download 1: End Mill for Hardened Steel 4 Flute Corner Radius End Mill File
Download 2: End Mill for Hardened Steel 4 Flute Corner Radius End Mill File

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