Sumitomo 16GC257 Pcbn Turning Insert Diamond BN350

Product Description

The SUMITOMO 16GC257 is a polycrystalline cubic boron nitride (PCBN) turning insert designed for hard-material machining applications. Carrying the ANSI code NUDNMA432 and ISO code NU-DNMA150408, this insert features a 55-degree diamond shape, negative rake geometry, and a 0 degree relief angle. The BN350 grade is uncoated and suited for interrupted and continuous turning of hardened steels and other difficult-to-machine ferrous materials. With a 0.5 inch inscribed circle and a 0.03125 inch corner radius, it delivers tight tolerances on finish cuts. Licensed machinists and CNC tooling specialists are the primary users of this insert type.

This insert is applied in CNC turning centers and manual lathes where hard turning replaces or supplements grinding operations. The NUDNMA432 geometry is appropriate for finishing and semi-finishing passes on hardened ferrous workpieces, typically in the 45 HRC and above range. The single cutting edge configuration and chip breaker style A support controlled chip formation in these demanding cuts. It is commonly used in automotive, tooling, and precision-parts manufacturing environments.

Key Features

• PCBN insert material for hard-material turning applications
• BN350 uncoated grade with negative rake and 0 degree relief angle
• 55-degree diamond insert shape (ANSI shape code D) for versatile entry angles
• 0.5 inch (12.70 mm) inscribed circle with 0.03125 inch corner radius
• Insert thickness of 0.1875 inch for rigid tool-body seating
• Compatible with clamp and pin holding methods for secure clamping under high cutting forces
• Meets ANSI and ISO 13399 standards

Compatibility

Designed as an OEM-style replacement or direct tooling insert for turning tool holders accepting NUDNMA432 geometry inserts per ANSI and ISO 13399 standards.

Installation Notes

Installation should be performed by a qualified CNC machinist or tooling technician with the machine in a fully stopped and locked-out state before insert indexing or replacement. Seat the insert firmly against the pocket locating surfaces and torque the clamping screw according to the tool-holder manufacturer specifications. Inspect the insert pocket for chips or wear debris before seating a new insert, as contamination can cause premature edge failure or poor surface finish. Verify coolant flow direction and pressure settings are appropriate for PCBN tooling before resuming cuts.