Accupro C911-31224 Thread Mill 5/16-24 Internal Carbide

Product Description

The ACCUPRO C911-31224 is a helical flute thread mill designed for cutting internal 5/16-24 UNF threads in a CNC milling environment. Built from micrograin solid carbide and coated with TiAlN, it delivers the hardness and heat resistance needed for demanding materials and high-speed feeds. The tool features three right-hand flutes, a 0.235-inch cutting diameter, and a 0.625-inch length of cut. The 0.25-inch shank diameter fits standard ER and end mill collet systems. Licensed machinists and CNC setup technicians install this tool for precision thread milling on ferrous and non-ferrous workpieces where tapping is impractical or thread quality requirements are tight.

This thread mill is suited for production and job-shop environments requiring accurate internal UNF threads in confined bores or hard materials. The 5/16-24 thread profile and 24 TPI spec make it appropriate for applications such as hydraulic fittings, instrument housings, and aerospace components where thread form accuracy is critical. It is used in vertical and horizontal machining centers capable of helical interpolation. Coolant-through is not supported, so surface flood or mist coolant is the standard approach during operation.

Key Features

• Micrograin solid carbide construction for rigidity and wear resistance
• TiAlN coating reduces heat buildup and extends tool life in ferrous materials
• Three right-hand helical flutes for smooth chip evacuation during thread milling
• 0.235-inch cutting diameter with 0.625-inch length of cut for full thread engagement
• 5/16-24 UNF internal thread profile, 24 TPI
• Shank diameter tolerance of 0.0003 inches for accurate collet seating

Compatibility

Designed for CNC machining centers capable of helical interpolation, accepting a 0.25-inch shank diameter in standard collet or end mill holders. Suited for cutting internal 5/16-24 UNF threads.

Installation Notes

Thread mills must be run on a CNC machine with helical interpolation capability — manual mills cannot execute the required toolpath. Confirm tool runout with a dial indicator before production runs, as excessive runout will degrade thread form. Power down the spindle and follow lockout procedures before changing or inspecting the tool. Refer to the machine control and toolholder manufacturer specifications for proper collet torque and toolholder projection.