Kennametal 4121689 Turning Insert SNMG643MS KCU25 Carbide

Product Description

The KENNAMETAL 4121689 is a solid carbide turning insert in the SNMG643MS configuration, grade KCU25, finished with an AlTiN PVD coating. It features a 90-degree square insert shape with a 3/4 inch inscribed circle, a 3/64 inch (0.0469 inch) corner radius, and a 1/4 inch insert thickness. The MS chip breaker geometry is rated for roughing and medium machining operations. With 8 available cutting edges, a negative rake angle of 13 degrees, and a honed cutting edge style, this insert delivers moderate wear resistance and toughness across a wide range of workpiece materials. It is installed by machinists and CNC turning specialists in production and job-shop environments.

This insert is suited for turning, facing, and boring operations on steel, stainless steel, cast iron, aluminum and non-ferrous materials, and superalloys including titanium. It performs across roughing and medium-duty cutting passes where balanced toughness and wear resistance are required. The KENLOC series insert is held via clamp or pin methods and carries a neutral hand designation, making it compatible with standard SNMG-style toolholders used on CNC lathes and turning centers in both residential-scale job shops and heavy industrial production lines.

Key Features

• SNMG643MS geometry with 90-degree square shape and negative side clearance for stable, rigid cutting
• AlTiN PVD coating for elevated heat resistance and extended tool life on steel and stainless applications
• 8 cutting edges per insert maximize cost-per-edge value in high-volume turning operations
• MS chip breaker supports both roughing and medium machining passes in a single insert style
• Rated for Steel (P), Stainless Steel (M), Cast Iron (K), Aluminum and Non-Ferrous (N), and Superalloys and Titanium (S) workpiece materials
• Compatible with clamp and pin insert holding methods; neutral hand orientation

Compatibility

Designed as an OEM-style replacement for SNMG643MS toolholders in the KENLOC series. Conforms to ANSI insert code SNMG643 and ISO insert code SNMG190612 (ISO code SNMG190612MS). Suitable for standard SNMG-style clamp and pin toolholders accepting a 3/4 inch inscribed circle, 1/4 inch thick square insert.

Installation Notes

Installation is performed by a qualified machinist or CNC tooling technician. Power down and lock out the machine spindle before changing inserts. Seat the insert fully against the toolholder pocket before engaging the clamp or pin, and inspect the pocket for chips or debris that could affect seating. Follow toolholder manufacturer torque guidance for the clamping screw; do not overtighten, as carbide inserts are brittle and susceptible to fracture under uneven clamping load.