Hertel E4040020 Square End Mill 5/16 in 4 Flute Cobalt

Product Description

The HERTEL E4040020 is a cobalt square end mill designed for precision material removal in ferrous and high-temperature alloy applications. Built from M42 cobalt high-speed steel, it handles higher heat generation than standard M2 HSS tooling, making it well suited for stainless steels, alloy steels, and work-hardening materials. The cutter measures 0.3125 inches in diameter with a 1.375-inch length of cut and a 0.375-inch shank diameter. A titanium nitride (TiN) surface treatment increases surface hardness and reduces friction at the cutting edge. The four-flute, single-end geometry is centercutting, allowing plunge entry as well as conventional peripheral and slot milling operations.

This end mill is used in manual mills, CNC machining centers, and knee mills across job shops, maintenance facilities, and production environments. Its 3.125-inch overall length is a standard reach suitable for the majority of general-purpose milling work. The TiN coating and M42 substrate combination makes it a practical choice for shops that cut a mix of mild steel, 304 and 316 stainless, and medium-alloy materials where uncoated HSS tooling wears prematurely. Machinists, tool-and-die makers, and maintenance technicians working with manual or CNC equipment install and replace this style of tooling.

Key Features

• M42 cobalt HSS substrate provides higher red-hardness than standard M2 for improved performance in tough alloys
• TiN finish reduces friction and improves wear resistance at the cutting edge
• Centercutting design allows direct plunge cuts without a pre-drilled pilot hole
• Four-flute configuration balances chip clearance with surface finish quality
• 3/8-inch shank fits standard R8, ER, and Weldon-style collet and end mill holders
• Single-end geometry for standard milling, slotting, and profiling operations

Compatibility

Designed as a standard-shank replacement cobalt end mill for use in any manual or CNC milling machine equipped with a 3/8-inch collet, end mill holder, or Weldon-style chuck.

Installation Notes

End mills of this type are installed and changed by machinists and tool-and-die professionals. Always de-energize and lock out the spindle before changing cutting tools. Confirm the tool holder bore and collet size match the 0.375-inch shank before tightening. Inspect the shank and holder for chips or burrs that would cause runout before securing the tool.