CNMG 120404-MM OS5105 Carbide Turning Insert

The CNMG 120404-MM OS5105 is a negative-rake carbide turning insert engineered for machining hardened steels in the range of HRC 40–60. With its 80° rhombic geometry and a small 0.4 mm corner radius, it provides high precision and stable cutting performance for semi-finishing and finishing applications. The sharp nose radius is ideal for achieving accurate dimensional tolerances and fine surface finishes on hardened workpieces.

Produced in the OS5105 grade, this insert features a colorful CVD coating on a tough carbide substrate. It offers superior wear resistance and thermal stability while minimizing the risk of chipping during continuous or interrupted cutting. The MM chipbreaker is optimized for steel turning, ensuring efficient chip evacuation and stable cutting forces, even at lower cutting speeds required for hardened materials.

Compatible with standard external turning toolholders such as MCLNR, PCLNR, and DCLNR, the CNMG 120404-MM OS5105 provides reliability and productivity in automotive, mold, and general engineering applications where hardened steel machining is required.

Code Breakdown:

• C – Insert shape: 80° rhombic

• N – Clearance angle: 0° (negative rake)

• M – Tolerance class (medium)

• G – Insert with hole and chipbreaker

• 12 – Insert size: 12 mm

• 04 – Insert thickness: 4.76 mm

• 04 – Corner radius: 0.4 mm

• MM – Chipbreaker for general steel machining

• OS5105 – CVD-coated grade for hardened steels

Key Features:

• CNMG-style 80° rhombic insert

• Size: 12×12 mm, thickness 4.76 mm, radius 0.4 mm

• Grade OS5105 – CVD colorful coating, high wear resistance

• MM chipbreaker for steel machining with chip control

• Negative rake design for strength and stability

• Fits holders: MCLNR, PCLNR, DCLNR

• Suitable for hardened steels HRC 40–60

Grade Information (OS5105):

• Coating: CVD, colorful

• Application: Turning of hardened steels

• Best for: Semi-finishing and finishing operations

• Material hardness: HRC 40–60

• Cutting speed: 60–150 m/min