Carmex MT0250C0520UN Thread Mill 1/4-20 Internal 3 Flute Carbide

Product Description

The CARMEX MT0250C0520UN is a solid carbide helical flute thread mill designed for cutting internal 1/4-20 UNC threads in a single helical pass. With a 0.177-inch cutting diameter, a 0.48-inch length of cut, and a TiAlN coating, this tool delivers consistent thread geometry and extended tool life in production and job-shop environments. The three-flute design promotes chip evacuation and smooth cutting action. Machinists and CNC programmers use this tool in machining centers where thread milling is preferred over tapping, particularly in hard or abrasive materials where the TiAlN coating provides thermal and wear resistance.

This thread mill is suited for internal 1/4-20 UNC threaded holes in ferrous and non-ferrous workpieces across aerospace, automotive, mold and die, and general precision machining applications. The right-hand flute direction and 20 TPI configuration match standard UNC fastener requirements. With a 0.25-inch shank diameter and 2.5-inch overall length, it fits standard ER or milling collet holders on 3-axis and 5-axis machining centers. It is not configured for coolant-through spindle delivery.

Key Features

• Solid carbide construction in material grade MT7 for rigidity and wear resistance in hard workpiece materials
• TiAlN coating provides high-temperature resistance and extended tool life in dry or semi-dry cutting conditions
• Three right-hand helical flutes promote efficient chip evacuation during internal thread milling
• Cuts 1/4-20 UNC internal threads with a 0.177-inch cutting diameter and 0.48-inch length of cut
• 0.25-inch shank diameter with 2.0-inch shank length fits standard collet and milling chuck toolholders
• Single-pass helical interpolation capability reduces cycle time compared to single-point threading

Compatibility

Designed for machining centers capable of helical interpolation and programmed for 1/4-20 UNC internal thread milling. Compatible with standard 0.25-inch ER collet chucks and milling holders.

Installation Notes

Tool setup and operation should be performed by a qualified CNC machinist or tooling engineer. Secure the shank fully in a collet or milling chuck to the recommended engagement depth before spindle operation. Verify helical interpolation parameters in the CNC program match the 1/4-20 UNC thread pitch before cutting. This tool is not configured for coolant-through delivery; apply cutting fluid externally as required by the workpiece material.