Kennametal 4050537 NPR331 KCU25 Carbide Profiling Insert

Product Description

The KENNAMETAL 4050537 is a solid carbide profiling and turning insert in the Top Notch series, designed for precision material removal on CNC lathes and turning centers. It carries the NPR331 insert style designation and is manufactured in grade KCU25, a fine-grain carbide substrate finished with an AlTiN coating applied via PVD process. The parallelogram-shaped insert measures 0.7330 inches in length, 0.3750 inches in inscribed circle diameter, and 0.1875 inches thick, with a 0.0156-inch corner radius and a maximum depth of cut of 0.2443 inches. Negative rake geometry and a 55-degree included angle support stable, controlled cuts on a broad range of workpiece materials. Installed by CNC machinists and toolroom operators, it is secured by screw-clamp holding.

This insert is suited for profiling and turning operations in both production and job-shop environments. The KCU25 grade with AlTiN PVD coating is engineered for use on steel, stainless steel, cast iron, non-ferrous metals, and superalloys including titanium. With four cutting edges per insert, it delivers multiple tool lives per unit before replacement. The right-hand configuration is the standard orientation for conventional OD turning on most lathes. It is identified under ISO code KNGX220404R25 and also cross-references as NPR331N.

Key Features

• KCU25 fine-grain solid carbide substrate with AlTiN PVD coating for extended wear resistance
• Four usable cutting edges per insert for maximum tool life economy
• 0.0156-inch (0.40 mm) corner radius suits profiling and contour turning detail work
• Maximum depth of cut of 0.2443 inches supports moderate stock removal passes
• Negative rake, 55-degree included angle geometry provides stable cutting forces
• Screw-clamp insert holding method for secure, repeatable seating in compatible toolholders

Compatibility

Designed for use in Top Notch series screw-clamp toolholders accepting the NPR331 insert style. ISO equivalent designation is KNGX220404R25. Cross-reference part number is NPR331N. Verify toolholder pocket specifications before installation.

Installation Notes

Insert installation should be performed by a qualified machinist or toolroom technician with the machine spindle fully stopped and the turret in a safe index position. Use the appropriate torx or hex key at the manufacturer-specified clamp screw torque range for the toolholder series — do not overtighten, as carbide inserts are brittle and can fracture under uneven clamping loads. Inspect the insert pocket and clamp for chips or debris before seating a new insert. Confirm cutting edge engagement and runout before returning the machine to production feeds and speeds.