Sumitomo 1657AVS Pcbn Turning Insert VNGA331 3/8 Inch Ic

Product Description

The SUMITOMO 1657AVS is a polycrystalline cubic boron nitride (PCBN) turning insert designed for precision machining of hard and abrasive workpiece materials. Manufactured in the VNGA insert style with a 35-degree diamond (rhombic) shape, this uncoated, multi-tipped insert delivers moderate wear resistance combined with sufficient toughness for demanding interrupted and continuous turning operations. The inscribed circle measures 3/8 inches, insert thickness is 0.1875 inches, and the corner radius is 0.0156 inches (1/64 inch). The neutral hand orientation and negative rake geometry make it suitable for rigid, well-supported setups on CNC turning centers.

This insert is applied in finishing and semi-finishing operations on hardened ferrous materials, cast iron, and superalloys. Its BN250 grade is classified under ISO application group H, targeting hardened materials requiring a balance of wear resistance and edge toughness. It is appropriate for both high-production shop environments and toolrooms requiring consistent dimensional results on hard-turned components. The VNGA platform is widely used in external diameter turning and facing operations on modern CNC lathes.

Key Features

• PCBN insert material provides hardness well above carbide for machining hardened steels and cast iron
• BN250 grade targets ISO H-class workpiece materials: hardened steels, cast iron, and superalloys
• Uncoated (bright) finish maintains sharp edge geometry without coating buildup
• Negative rake and negative side clearance geometry suited for rigid, high-speed turning setups
• Two cutting edges per insert reduce per-edge tooling cost
• Chip breaker style A with clamp and pin holding method for secure, repeatable seating

Compatibility

Designed for use in VNGA-style toolholders accepting a 331 (ANSI) or 160404 (ISO) insert size with clamp and pin holding. Conforms to ANSI and ISO 13399 insert standards.

Installation Notes

Installation should be performed by a qualified machinist or tooling technician. Power down and lock out the machine spindle before seating or replacing inserts. Use the correct torque driver and clamp hardware specified by the toolholder manufacturer — do not overtighten, as PCBN inserts are brittle and susceptible to edge chipping from seating stress. Inspect the toolholder pocket for debris or damage before indexing to a fresh cutting edge.