Sandvik Coromant 7861116 Turning Insert VBMT21.51-UF 4425

Product Description

The SANDVIK COROMANT 7861116 is a VBMT21.51-UF 4425 grade carbide turning insert designed for precision finish turning on CNC lathes and turning centers. It features a 35-degree diamond (rhombic) insert shape with a 5-degree relief angle and a neutral hand orientation. The insert carries a CVD-applied multilayer coating of Al2O3, TiN, and TiCN, delivering high wear resistance suited to continuous cuts in steel and interrupted passes in cast iron. With a 0.25-inch inscribed circle and a 0.4 mm corner radius, this insert targets tight-tolerance, fine-surface finishing passes where controlled chip formation is critical. It is installed by CNC machinists and turning specialists in production and job-shop environments.

This insert belongs to the CoroTurn 107 series and is engineered primarily for finishing operations on steel workpieces (ISO material group P) with secondary suitability for cast iron (ISO material group K). The UF chip breaker geometry promotes controlled chip flow at light depths of cut and moderate-to-high feed rates typical of finish turning. Toolholders that accept VBMT-style inserts with clamp or screw holding methods are the intended mounting platform. The two cutting edges per insert help reduce cost-per-edge in high-volume production runs.

Key Features

• CVD multilayer coating: Al2O3, TiN, and TiCN for high wear resistance in steel finishing
• 35-degree diamond (V) insert shape with 5-degree positive relief angle for low cutting forces
• UF chip breaker geometry optimized for finishing chip control
• Neutral hand orientation for flexible toolholder compatibility
• Two cutting edges per insert
• CoroTurn 107 series — compatible with clamp and screw holding systems

Compatibility

Designed for use in CoroTurn 107 series toolholders accepting VBMT-style inserts with clamp or screw holding methods. ANSI insert code VBMT21.51; ISO insert code VBMT 11 02 04.

Installation Notes

Installation is performed by qualified CNC machinists or tooling technicians. Power down and lock out the machine spindle before seating or indexing the insert. Seat the insert fully in the pocket and tighten the clamping screw or clamp to the toolholder manufacturer's specified torque using the correct Torx or hex key. Inspect the insert seat and pocket for chips or debris before each insert change to avoid seating errors that can damage the toolholder.