Hertel H59875781 Boring Insert TPGH321 HP520B Carbide

Product Description

The HERTEL H59875781 is a solid carbide boring insert designed for precision internal turning and boring operations on CNC and manual lathes. Manufactured to TPGH321 style with a 60-degree triangular geometry, it carries a Titanium Nitride (TiN) coating applied via PVD process, improving surface hardness and wear resistance over uncoated carbide. The insert measures 3/8 inches inscribed circle, 1/8 inches thick, and features a 0.021-inch corner radius with an 11-degree relief angle. It is held in the toolholder by a screw-clamp method. Material grade is C5, making it suitable for general-purpose ferrous and non-ferrous machining applications where a fine to medium finish is required.

This insert is used in boring bars and internal turning toolholders that accept the TPGH321 insert style. Typical applications include finish and semi-finish boring of through-holes and blind bores in steel, cast iron, and ductile metals on production and job-shop lathes. The 60-degree triangle shape provides three usable cutting edges per insert, extending tooling value across multiple setups. It is installed by machinists and tool-and-die technicians in both light industrial and high-volume production environments. Package quantity is 1 insert; minimum order quantity is 10 pieces.

Key Features

• Solid carbide substrate with PVD Titanium Nitride (TiN) coating for extended tool life
• TPGH321 style insert geometry with 60-degree triangular shape and 11-degree relief angle
• 0.021-inch corner radius for fine to semi-finish boring applications
• 3/8-inch inscribed circle and 1/8-inch thickness to ANSI insert size code 321
• Screw-clamp insert holding method for positive, repeatable seating
• Three usable cutting edges per insert

Compatibility

Designed for use in boring bars and internal turning toolholders that accept TPGH321-style screw-clamp inserts with a 3/8-inch inscribed circle.

Installation Notes

Installation should be performed by a qualified machinist with the machine fully powered down and the spindle locked before changing inserts. Use the correct Torx or hex key for the clamping screw specified by the toolholder manufacturer; do not overtighten, as this can fracture the carbide insert. Inspect the insert pocket and clamping screw for wear or debris before seating the new insert. Indexing to a fresh cutting edge follows the same procedure and does not require a new insert until all three edges are worn.