Sandvik Coromant 7860869 Turning Insert DCMT21.51-UM 4425

Product Description

The SANDVIK COROMANT 7860869 is a solid carbide turning insert in the DCMT style, designed for precision turning operations on CNC lathes and turning centers. Manufactured under the CoroTurn 107 series, it features a CVD-applied multilayer coating of TiCN, Al2O3, and TiN that provides wear resistance and thermal protection at the cutting zone. The insert has a 55-degree diamond shape, a 0.4 mm (0.0156 inch) corner radius, and a 1/4-inch (6.35 mm) inscribed circle. It carries a neutral hand orientation and is intended for use by machinists and toolroom technicians performing external turning, boring, and profiling on steel and cast iron workpieces.

This insert is rated primarily for steel (ISO material code P) and secondarily for cast iron (ISO material code K). The CoroTurn 107 series targets light to medium turning applications where precision chip control and surface finish consistency are priorities. The UM chip breaker geometry supports versatile cutting conditions across a range of depths of cut and feed rates. Typical installations involve single-point turning toolholders with clamp or screw holding methods on multi-axis CNC turning equipment.

Key Features

• CVD multilayer coating: TiCN, Al2O3, and TiN for extended tool life on steel and cast iron
• 55-degree diamond insert shape (ISO shape code D) for versatile profiling and turning passes
• UM chip breaker geometry for controlled chip evacuation across light to medium cuts
• 7-degree relief angle (clearance code C) with tolerance code M for consistent dimensional accuracy
• Two cutting edges per insert for cost-effective indexing
• Compatible with both clamp and screw holding methods

Compatibility

Designed for use in CoroTurn 107 series toolholders that accept DCMT-style inserts with a 1/4-inch inscribed circle. ISO code designation is DCMT 07 02 04-UM 4425. Verify toolholder seat geometry and clamping style (clamp or screw) before installation.

Installation Notes

Installation is performed by qualified machinists or toolroom technicians. Power down and lock out the machine spindle before indexing or replacing inserts. Use the correct torque driver for screw-seated inserts and inspect the toolholder pocket and seat for debris or wear before seating the new insert. Handle carbide inserts with care to avoid chipping the cutting edges prior to use.