Osg 5401200 Square End Mill 9/16 Inch 4 Flute Cobalt

Product Description

The OSG 5401200 is a cobalt square end mill designed for milling operations that demand heat resistance and durability in tough materials. Built to Series 540 specifications, it features a 9/16-inch cutting diameter, a 1-3/8-inch length of cut, and a 1/2-inch shank diameter for secure tool holder engagement. The 4-flute, right-hand spiral configuration with a 30-degree helix angle promotes efficient chip evacuation and smooth cutting action. The M42 cobalt steel construction provides elevated red hardness compared to standard HSS, making this end mill well suited for harder steels and abrasive workpiece materials. It ships uncoated and is sold as a single unit.

This end mill is intended for use in manual mills, knee mills, and CNC machining centers in job shop, maintenance, and production environments. With a 3-3/8-inch overall length and regular length classification, it fits standard tooling setups without extended-reach adapters. Machinists and tool-and-die tradespeople commonly select cobalt end mills like the 5401200 for interrupted cuts, hard ferrous materials, and applications where carbide tooling would be cost-prohibitive or prone to chipping. The non-centercutting geometry means this tool is intended for peripheral and side milling rather than plunge cutting.

Key Features

• M42 cobalt steel construction offers superior heat resistance compared to standard M2 HSS
• 4-flute design with 30-degree right-hand spiral helix for efficient chip flow in side milling
• 9/16-inch cutting diameter with 1-3/8-inch length of cut suits a wide range of milling depths
• 1/2-inch shank diameter compatible with standard end mill holders and collet chucks
• Uncoated finish suitable for use with cutting fluids on ferrous and non-ferrous materials
• Non-centercutting geometry — designed for peripheral, slot, and side milling applications

Compatibility

Designed as an OEM-style replacement or direct selection for applications requiring a regular-length, 4-flute cobalt square end mill with a 1/2-inch shank, compatible with standard end mill holders, R8 collets, and ER collet chucks sized for 1/2-inch shanks.

Installation Notes

Installation and tool changes should be performed by a qualified machinist with the machine in a fully stopped and locked-out state. Ensure the shank is fully seated and properly torqued in the tool holder per the holder manufacturer's specifications before running. Inspect the cutting edges for chips or wear before each use. Do not use this end mill for plunge entry due to its non-centercutting geometry.