Sandvik Coromant 5781837 Threading Insert 28 Tpi Un

Product Description

The SANDVIK COROMANT 5781837 is a solid carbide laydown threading insert from the CoroThread 266 series, designed for cutting left-hand external UN threads at 28 threads per inch. It carries a dual PVD coating of TiAlN and TiCrAlN, which delivers heat resistance and wear protection during threading operations on a range of workpiece materials. The insert features a 3/8-inch inscribed circle, a thickness of 5/32 inch (0.1563 inch), and a 60-degree included angle. It is used in CNC turning centers and threading toolholders by machinists and toolroom technicians performing precision thread-cutting work.

This insert is suited for external UN threading applications where left-hand thread geometry is required. The 266 insert style and 16 size code are consistent with SANDVIK COROMANT CoroThread 266 tooling systems. Typical applications include production threading of fasteners, fittings, and mechanical components in manufacturing environments. The chipbreaker designation A and single tooth per side configuration are appropriate for controlled chip management in threading passes. Machinists working in job shops or production facilities will find this insert applicable to both light and moderate threading operations.

Key Features

• Solid carbide substrate with PVD-applied TiAlN and TiCrAlN dual coating for wear and thermal resistance
• Left-hand external UN thread form at 28 TPI with a 60-degree included angle
• CoroThread 266 series insert style 266, size code 16
• 3/8-inch inscribed circle with 5/32-inch thickness for consistent toolholder seating
• Chipbreaker type A with single tooth per side for controlled chip formation
• Hole diameter of 0.1732 inch for positive clamping in compatible holders

Compatibility

Designed for use with SANDVIK COROMANT CoroThread 266 series toolholders that accept insert style 266, size code 16. The manufacturer catalog number for this insert is 266LG-16UN01A280M 1125. Verify toolholder pocket geometry and clamping requirements before installation.

Installation Notes

Installation should be performed by a qualified machinist or toolroom technician familiar with indexed threading inserts. Power down and lock out the machine spindle before changing inserts. Use the correct torque driver for the clamping screw to avoid over-tightening, which can fracture the carbide substrate. Confirm that the insert seats fully and flush in the pocket before resuming cutting operations.