Carmex S0250C2540UN Thread Mill 4-40 Unc 3 Flute Solid Carbide

Product Description

The CARMEX S0250C2540UN is a mini helical flute thread mill designed for cutting internal 4-40 UNC threads in a single helical interpolation pass. Built from solid carbide with a TiAlN coating, it delivers the hardness and heat resistance needed for productive threading in steel, cast iron, stainless, and non-ferrous alloys. The tool carries a 0.0830 inch cutting diameter, a 1/4 inch (0.2500 inch) shank diameter, and 3 flutes. It is intended for use in CNC machining centers where the spindle and control support helical interpolation. Machinists and tool-and-die professionals working in precision threading applications are the primary users of this tool.

This thread mill is suited for small-diameter internal thread production where tapping presents breakage risk or where a single tool must produce threads in a range of hole sizes. The 4-40 UNC designation targets fine-pitch fastener holes common in electronics enclosures, instrument housings, and light mechanical assemblies. The mini thread mill format keeps the tool compact for shallow-feature work. The 1/4 inch length of cut and 2-1/2 inch overall length allow reach into standard workpiece features without excessive overhang. Coolant-through capability is not present, so flood or mist cooling at the spindle is the typical approach.

Key Features

• Solid carbide construction rated to material grade MT7 for rigidity and wear resistance
• TiAlN coating improves heat resistance and extends tool life in ferrous and hardened materials
• 3-flute helical geometry produces internal 4-40 UNC threads in a single CNC interpolation pass
• 0.0830 inch cutting diameter with 40 teeth per inch matches 4-40 thread form precisely
• 1/4 inch shank diameter fits standard collet and end-mill holders on most CNC machining centers
• Mini thread mill classification suits tight-tolerance small-hole threading where tap breakage is a concern

Compatibility

Designed as an OEM-style threading solution for CNC machining centers capable of helical interpolation, this tool is compatible with standard 1/4 inch collet chucks and end-mill holders. No specific machine model compatibility data was provided by the manufacturer for this SKU.

Installation Notes

Installation and operation of this tool should be performed by a qualified CNC machinist or tooling professional. Secure the 1/4 inch shank in a properly sized collet or end-mill holder and verify runout before cutting. Confirm that the machining center control supports helical interpolation and that the programmed thread mill cycle matches the 4-40 UNC thread form. Because coolant-through is not available on this tool, direct flood or mist cooling at the cutting zone is recommended to manage chip evacuation and heat in the cut.