Sumitomo 1657W0Y Pcbn Turning Insert Diamond BN250

Product Description

The SUMITOMO 1657W0Y is a polycrystalline cubic boron nitride (PCBN) turning insert designed for precision machining of hard and difficult-to-cut materials. This uncoated insert features a 35-degree diamond shape (V-style) with a negative rake geometry and belongs to the Series V product line under ANSI designation 2MDVNMA331. With an inscribed circle of 0.375 inches and a corner radius of 0.0156 inches (1/64 inch), it delivers tight tolerances in finishing and semi-finishing applications. The BN250 grade PCBN substrate provides high hardness and thermal stability suited for interrupted and continuous cuts on hardened steels and hard materials. Machinists and CNC turning specialists install this insert in compatible toolholders on turning centers.

This insert is intended for turning operations on hard workpiece materials, including hardened steels and other materials classified under secondary workpiece material code H. The 2MD-VNMA insert style and ISO designation 2MD-VNMA160404 confirm compatibility with toolholders designed around this geometry. With only 2 cutting edges, the insert is positioned for applications where edge precision and material hardness resistance are the primary requirements. Typical use cases include finishing passes on hardened components in production turning environments where surface finish and dimensional accuracy are critical.

Key Features

• PCBN substrate (BN250 grade) provides exceptional hardness for cutting hard materials
• Uncoated insert with negative rake for controlled chip formation on hardened steels
• 35-degree diamond insert shape with 2 cutting edges for precision turning
• Corner radius of 0.0156 inches supports fine surface finish requirements
• Maximum depth of cut of 0.020 inches suited for finishing and light semi-finishing
• Clamp and pin holding method for secure, repeatable insert seating

Compatibility

Designed for use in toolholders accepting the 2MD-VNMA insert style per ANSI designation 2MDVNMA331 and ISO designation 2MD-VNMA160404. Suitable for hard material turning applications (material grade C4, secondary workpiece material code H) on CNC turning centers.

Installation Notes

Installation should be performed by a qualified machinist or CNC tooling technician with the machine powered off and in a locked-out state. Ensure the toolholder pocket and seating surfaces are clean and free of debris before inserting. Use the specified clamp and pin holding method to achieve proper clamping torque per the toolholder manufacturer guidelines. Verify insert orientation and rake angle alignment before resuming cutting operations.