Sumitomo 16GC255 Pcbn Turning Insert 80 Diamond Uncoated

Product Description

The SUMITOMO 16GC255 is a Polycrystalline Cubic Boron Nitride (PCBN) turning insert designed for precision material removal on demanding workpiece materials. Manufactured to ANSI code NUCNMA433 and ISO code NU-CNMA120412, this uncoated, negative-rake insert features an 80-degree diamond shape with a 0.5-inch inscribed circle and a corner radius of 0.0469 inches (3/64 inches). The BN350 grade designates a PCBN substrate suited for interrupted and continuous cuts on hard and abrasive materials. Machinist and toolroom technicians working on CNC lathes and turning centers will find this insert appropriate for high-speed finishing and semi-finishing passes where standard carbide grades fall short.

This insert is intended for turning operations on cast iron, hard materials, and superalloys. Its neutral hand orientation makes it adaptable to both right-hand and left-hand toolholders configured for CNMA-series inserts. Typical applications include finishing bores, turning hardened steel components, and machining nickel-based superalloy parts in aerospace, automotive, and heavy-industry production environments. The single cutting edge configuration is standard for PCBN tooling of this geometry, where maximizing edge integrity per index is critical to surface finish and dimensional control.

Key Features

• PCBN insert material (Polycrystalline Cubic Boron Nitride) for hard and abrasive workpiece materials
• Uncoated BN350 grade optimized for cast iron, hard materials, and superalloys
• 80-degree diamond insert shape (Shape Code C) for versatile turning geometry
• 0.5-inch inscribed circle (12.70 mm) with 3/64-inch corner radius for controlled finish
• Negative rake, 0-degree clearance (Code N), Tolerance Code M for consistent seating
• Clamp and pin holding method for secure insert retention in compatible toolholders
• Compliant with ANSI and ISO 13399 standards for interchangeable tooling documentation

Compatibility

Designed as an OEM-style replacement for CNMA-series PCBN turning inserts used in standard CNMA toolholders accepting a 0.5-inch inscribed circle, 3/16-inch thick diamond insert with clamp and pin retention.

Installation Notes

PCBN turning inserts should be installed and indexed by a qualified machinist or toolroom technician. Power down and lock out the machine spindle before changing inserts. Use the appropriate torque wrench and manufacturer-specified clamp hardware when securing the insert to avoid fracturing the PCBN substrate. Handle PCBN inserts carefully, as the cutting edges are brittle and susceptible to chipping from impact or improper seating.