Kennametal 4121700 TNMG431MS KCU25 Carbide Turning Insert

Product Description

The KENNAMETAL 4121700 is a TNMG431MS grade KCU25 solid carbide turning insert with a Physical Vapor Deposition (PVD) AlTiN coating. It features a 60-degree triangular shape, a 0.5-inch inscribed circle, a 0.0156-inch corner radius, and a 0.1875-inch insert thickness. The MS chip breaker geometry is engineered for roughing and medium machining operations, delivering moderate wear-resistance and toughness across a range of workpiece materials. With 6 usable cutting edges and a neutral hand orientation, this insert fits into standard KENLOC toolholders using clamp or pin holding methods. It is installed and indexed by CNC machinists and turning center operators in production and job-shop environments.

This insert is suited for external turning, facing, and boring operations on steel, stainless steel, cast iron, aluminum and non-ferrous alloys, and superalloys including titanium. The KCU25 grade balances wear-resistance and toughness, making it effective across P, M, K, N, and S workpiece material classifications. It performs in both roughing passes and medium-duty cuts, with a maximum depth of cut of 0.2884 inches and a usable insert length of 0.8661 inches. Applications span general-purpose CNC turning in both production and maintenance machining contexts.

Key Features

• AlTiN PVD coating for heat resistance and extended tool life on steel and stainless steel
• MS chip breaker geometry optimized for roughing and medium machining
• 6 cutting edges per insert for lower per-edge tooling cost
• Negative rake and negative side clearance for high-stability interrupted and continuous cuts
• Compatible with clamp and pin holding methods in KENLOC-style toolholders
• Honed cutting edge style reduces micro-chipping on tough and abrasive workpiece materials

Compatibility

Designed as an OEM-style replacement insert for KENLOC-series toolholders accepting TNMG431 geometry inserts. Conforms to ANSI insert code TNMG431 and ISO insert code TNMG220404. Suitable for use across turning, facing, and boring applications on CNC lathes and turning centers.

Installation Notes

Installation and indexing should be performed by a qualified machinist with the machine fully powered down and the spindle locked. Seat the insert fully against the toolholder pocket before engaging the clamp or pin — partial seating causes premature edge failure. Follow the toolholder manufacturer torque guidelines for clamping screws. Inspect the insert pocket for chips or debris before indexing to a fresh cutting edge.