Hertel 8851944 TPG431 HT115CR Cermet Turning Insert

Product Description

The HERTEL 8851944 is a cermet, uncoated turning insert in the TPG431 style, designed for external turning operations on CNC and manual lathes. Manufactured in a 60-degree triangular shape with a positive rake geometry, it carries the HT115CR grade designation and is suited for finishing and semi-finishing cuts where edge sharpness and wear resistance are priorities. The insert features a 1/2-inch inscribed circle, a 3/16-inch thickness, and a 1/64-inch corner radius. The neutral hand orientation allows flexible toolholder application. Licensed machinists and CNC setup technicians are the primary installers of this insert type.

This insert is intended for precision turning applications where cermet substrate performance is required. Cermet grades excel in high-speed finishing of steel and stainless steel, producing tight tolerances and excellent surface finish at elevated cutting speeds. The TPG431 form factor fits standard top-clamp toolholders designed for triangular inserts with a P clearance angle and G tolerance class. It is appropriate for both light production environments and job-shop turning setups. The uncoated cermet substrate makes it well suited for dry or minimal-lubrication cutting conditions where coating adhesion could be a limiting factor.

Key Features

• Cermet, uncoated substrate (grade HT115CR) for high-speed steel and stainless finishing
• 60-degree triangular insert shape with positive rake for reduced cutting forces
• 1/64-inch corner radius for tight-tolerance finishing passes
• 11-degree relief angle (clearance code P) with G tolerance class for consistent seating
• Neutral hand — compatible with left- and right-hand top-clamp TPG toolholders
• No chip breaker geometry — flat top for maximum edge versatility

Compatibility

Designed as a direct-fit replacement for standard TPG431 insert pockets on top-clamp turning toolholders accepting a 60-degree triangular insert with P clearance angle and G tolerance class.

Installation Notes

Installation should be performed by a qualified machinist or CNC technician with the machine in a fully stopped and locked-out state before any insert change. Use a torque wrench appropriate for the toolholder clamp screw specification provided by the toolholder manufacturer — do not overtighten the clamp. Inspect the insert pocket and clamp for chips or debris before seating the new insert, and verify that the insert is fully seated and indexed before resuming cuts. Handle cermet inserts carefully, as the substrate is more brittle than carbide and susceptible to chipping from impact.