Sandvik Coromant 7860870 Turning Insert DCMT21.52-UM 4425

Product Description

The SANDVIK COROMANT 7860870 is a solid carbide turning insert designed for precision external and internal turning operations on CNC lathes and turning centers. Designated DCMT21.52-UM 4425, it features a 55-degree diamond insert shape with a 7-degree relief angle and a 0.79 mm (0.0313 inch) corner radius. The insert carries a three-layer CVD coating of TiCN, Al2O3, and TiN, placing it in SANDVIK COROMANT grade 4425 — a wear-resistant general-purpose grade optimized for steel and cast iron machining. With two cutting edges per insert and a neutral hand orientation, it suits a wide range of finishing and medium turning applications. Licensed machinists and CNC programmers working in job shops, production facilities, and contract machining environments rely on inserts of this type for consistent surface finish and dimensional accuracy.

This insert is part of the CoroTurn 107 series, engineered for positive-rake turning of external profiles, shoulders, and facing cuts. Its primary workpiece material classification is steel (ISO code P), with a secondary classification for cast iron (ISO code K), making it a productive choice across both ferrous material categories. The UM chip breaker geometry is suited for universal turning at light-to-medium depths of cut, providing reliable chip control across varying feed rates. It is applicable in both roughing-to-finish and finish-turning contexts where tight tolerances and repeatable edge life are required.

Key Features

• CVD-applied three-layer coating: TiCN, Al2O3, and TiN for extended tool life in steel and cast iron
• Grade 4425 solid carbide substrate balances hardness and toughness for general turning
• 55-degree diamond (D) insert shape with 7-degree clearance angle for versatile profiling
• UM chip breaker geometry delivers reliable chip control in light-to-medium turning passes
• Two usable cutting edges per insert reduce cost-per-edge in production environments
• Clamp and screw holding method compatible with standard CoroTurn 107 toolholders

Compatibility

Designed for use in SANDVIK COROMANT CoroTurn 107 series toolholders. ISO code DCMT 07 02 08-UM 4425. Compatible with toolholder seats accepting DCMT insert style with C clearance code, M tolerance code, and a 2.80 mm hole diameter. Verify toolholder seat specification before installation.

Installation Notes

Insert seating and clamping should be performed by a qualified machinist following the toolholder manufacturer guidelines for torque and seating sequence. Power down and lock out the machine spindle before changing inserts. Inspect the toolholder pocket for chips or wear before seating a new insert, as debris under the insert seat will affect edge geometry and tolerances. Dispose of worn carbide inserts in accordance with applicable shop waste regulations for cutting tool materials.