Sandvik Coromant 7861221 TNMG331-LC 4425 Turning Insert

Product Description

The SANDVIK COROMANT 7861221 is a TNMG331-LC solid carbide turning insert from the T-Max P series, designed for external and internal turning operations on steel workpieces. It features a triangular insert shape with a 60-degree included angle, a 3/8-inch inscribed circle, and a 0.0156-inch corner radius. The LC chip breaker geometry controls chip flow during moderate to heavy roughing and finishing passes. The CVD-applied multilayer coating stack of Al2O3, TiCN, and TiN delivers wear resistance and thermal barrier performance at the cutting edge. This insert is installed by CNC machinists and lathe operators in production and job-shop environments.

The 7861221 is engineered for primary use on steel (ISO material group P), making it well suited for turning low-alloy, carbon, and mild steel components on CNC lathes and turning centers. The Neutral hand orientation allows use on standard right-hand toolholders in both OD and ID turning applications. With 6 cutting edges per insert, it offers extended tool life per unit across high-volume production runs. The LC chip breaker is optimized for controlled chip formation in medium-duty steel turning, reducing cycle interruptions caused by stringy chip buildup.

Key Features

• CVD multilayer coating: Al2O3, TiCN, and TiN for thermal and abrasion resistance
• LC chip breaker geometry for controlled chip evacuation in steel turning
• 6 usable cutting edges per insert for extended cost-per-edge value
• 0.0156-inch corner radius suits medium-finish surface requirements
• Neutral hand orientation compatible with standard right-hand TNMG toolholders
• Clamp and screw insert holding method for secure seating under interrupted or continuous cuts

Compatibility

Designed for use in TNMG-style toolholders that accept a 3/8-inch inscribed circle triangular insert with clamp or screw holding. ISO designation TNMG 16 04 04-LC 4425 and industry standard number TNMG 16 04 04-LC 4425 apply. Insert size code 1604. Compatible with T-Max P series tooling systems.

Installation Notes

Installation is performed by qualified machinists or CNC tooling technicians. Power down and lock out the spindle before indexing or replacing inserts. Seat the insert fully against the toolholder pocket locating surfaces before tightening the clamp or screw to avoid edge chipping on first contact. Inspect the insert pocket and clamp for wear or debris before each index to maintain repeatable tool geometry.