Hertel 8851992 Turning Insert TPGR321LB HT115CR Cermet

Product Description

The HERTEL 8851992 is a cermet uncoated turning insert in the TPGR321LB style, designed for precision external turning operations on CNC and manual lathes. Rated grade HT115CR, this insert features a 60-degree triangular shape with a positive rake angle of 14 degrees and an 11-degree relief angle, promoting free-cutting action and reduced cutting forces. The left-hand configuration and chip breaker designation R make it well-suited for finish and semi-finish turning of steel and stainless steel. With a 3/8-inch inscribed circle and a 1/64-inch corner radius, this insert delivers tight tolerances and consistent surface finishes. It is installed using a clamp-style holding method and is compatible with TPGR-style toolholders.

This insert is used in precision turning applications across job shops, production machining environments, and maintenance facilities. The cermet substrate provides wear resistance and thermal stability at moderate to high cutting speeds, making it appropriate for finishing passes on ferrous materials where surface finish and dimensional accuracy are priorities. Machinists and CNC operators working with TPGR-style toolholders will find this insert a direct fit for applications requiring left-hand cutting geometry. It is sold individually but carries a minimum order quantity of 10 units.

Key Features

• Cermet uncoated substrate grade HT115CR for wear resistance in finish turning of ferrous materials
• 60-degree triangular insert shape with positive rake angle of 14 degrees for reduced cutting forces
• Left-hand cutting orientation with chip breaker style R for controlled chip evacuation
• 1/64-inch corner radius (0.0156 inches) for tight-tolerance finish passes
• 3/8-inch inscribed circle (0.3750 inches) and insert length of 0.6299 inches (16 millimeters)
• Clamp-style holding method; compatible with TPGR-designated toolholders

Compatibility

Designed for use in TPGR-style clamp-type turning toolholders accepting a 321 insert size with left-hand geometry. Consult toolholder manufacturer specifications to confirm seating pocket compatibility before installation.

Installation Notes

Installation is performed by a qualified machinist or CNC operator. Power down and lock out the machine before indexing or replacing inserts. Use the appropriate torque wrench and clamping hardware specified by the toolholder manufacturer to seat the insert securely without over-torquing the clamp screw. Inspect the insert pocket for chips or damage before seating a new insert, and verify left-hand orientation matches the intended cutting direction of the setup.