Sandvik Coromant 5781891 Threading Insert 27 Tpi Npt

Product Description

The SANDVIK COROMANT 5781891 is a laydown threading insert from the CoroThread 266 series, designed for external NPT threading operations on CNC lathes and turning centers. This single-tooth insert is manufactured from solid carbide and features a dual-layer PVD coating of TiCrAlN and TiAlN for extended wear resistance at elevated cutting temperatures. Rated at 27 threads per inch with a 60-degree included angle, it produces right-hand NPT external threads in a single or multi-pass strategy. With a 3/8-inch inscribed circle and a thickness of 0.1563 inches, the 5781891 fits standard 266-series toolholders used by machinists and tool-and-die professionals across high-volume production environments.

This insert is suited for external NPT thread turning on pipe fittings, valves, and fluid-system components in precision machining environments. The NPT 27 TPI thread form is common in hydraulic, pneumatic, and general-purpose pipe thread applications across industrial, oil-and-gas, and mechanical contracting sectors. The A chipbreaker geometry supports controlled chip evacuation during threading passes. Typical applications include production turning shops, job shops running threaded pipe fittings, and maintenance machining operations requiring consistent NPT thread profiles.

Key Features

• Solid carbide substrate with PVD-applied TiCrAlN and TiAlN dual-layer coating for heat and wear resistance
• 27 TPI right-hand external NPT thread form with 60-degree included angle
• CoroThread 266 series insert style 266RG-16NT01A270M, grade 1125
• Single tooth per side design for precise thread profile control
• A chipbreaker geometry for reliable chip control during threading passes
• 3/8-inch (9.53 mm) inscribed circle fits standard 266-series toolholder seats

Compatibility

Designed as an OEM-specification replacement insert for SANDVIK COROMANT CoroThread 266 series toolholders accepting 16-size laydown threading inserts with a 0.1732-inch mounting hole diameter.

Installation Notes

Installation is performed by qualified machinists or toolroom personnel. Power down and lock out the machine spindle before seating or removing inserts. Verify correct torque on the clamping screw per toolholder manufacturer specifications and confirm insert is fully seated before resuming cutting operations. Follow ANSI and shop-specific tool change procedures; do not exceed the recommended depth of cut per pass for the thread profile.