Sandvik Coromant 7859251 Turning Insert CNMG543-PR 4415

Product Description

The SANDVIK COROMANT 7859251 is a CNMG-style indexable turning insert designed for external and internal turning operations on CNC lathes and turning centers. This insert carries the manufacturer grade 4415 and features a CVD-applied multilayer coating of TiCN, Al2O3, and TiN, providing wear resistance and thermal protection during continuous and interrupted cutting. It has an 80-degree diamond insert shape, a 5/8-inch (0.6250 inch) inscribed circle, a 1.19 mm (0.0469 inch) corner radius, and a 1/4-inch insert thickness. Part of the T-Max P series, it is suited for medium to finishing passes where edge security and surface finish are critical. Machinists and CNC operators install and index these inserts as part of routine tooling maintenance.

This insert is rated primarily for steel (ISO material code P) and secondarily for cast iron (ISO material code K), covering a wide range of ferrous turning applications. The PR chip breaker geometry is engineered to control chip flow and reduce cutting forces in medium-duty turning. Its neutral hand orientation makes it compatible with right-hand and left-hand toolholders designed for CNMG-style inserts. The ISO designation for this insert is CNMG 16 06 12-PR 4415. Typical applications include turning of shafts, flanges, housings, and other ferrous components on production turning equipment.

Key Features

• CVD multilayer coating: TiCN, Al2O3, and TiN for wear and thermal resistance
• 80-degree diamond insert shape (shape code C) with 4 cutting edges for maximum indexing value
• PR chip breaker geometry for controlled chip flow in medium turning of steel and cast iron
• 1.19 mm corner radius balances edge strength with surface finish capability
• Neutral hand — compatible with standard CNMG toolholder pockets
• Clamp and screw holding method for secure seating in the pocket

Compatibility

This insert is compatible with toolholders designed to accept CNMG-style inserts with a 5/8-inch inscribed circle (ISO size 16), 1/4-inch thickness, and a 0.2500-inch hole diameter. It is part of the SANDVIK COROMANT T-Max P series tooling system. Verify that the toolholder pocket geometry and clamping method match the clamp-and-screw configuration before installation.

Installation Notes

Indexable turning inserts are installed and indexed by qualified machinists and CNC tooling technicians. Always bring the spindle to a complete stop and follow lockout procedures before accessing the turret or toolholder. Use the correct torque wrench and insert key specified by the toolholder manufacturer when tightening the clamping screw — do not use impact tools. Inspect the insert pocket seat for chips or debris before seating a new insert to ensure full contact and accurate tool-nose positioning.