Osg 5220300 Square End Mill 1/4 in 2 Flute Cobalt Series 522

Product Description

The OSG 5220300 is a cobalt square end mill built for general-purpose milling in ferrous and non-ferrous materials. The cutter measures 0.25 inches in diameter with a 0.50-inch length of cut and a 0.375-inch shank diameter, giving it a compact profile suited for shallow slotting and peripheral milling passes. Manufactured from M42 cobalt high-speed steel, this double-end design delivers an uncoated cutting edge with a 30-degree spiral helix. The centercutting geometry allows plunge entry without a pre-drilled start hole. Overall length is 3.125 inches. It is installed and used by machinists and tool-and-die professionals on manual and CNC mills.

The OSG 5220300 is designed for use in job shop, production, and maintenance machining environments where cobalt tooling is preferred over carbide for its toughness and resistance to chipping under interrupted cuts. The regular-length body and 3/8-inch shank make it compatible with standard collet chucks and end mill holders found on vertical knee mills and CNC machining centers. Typical applications include slotting, side milling, and face milling in mild steels, stainless steels, and high-temperature alloys where uncoated cobalt performs reliably at moderate speeds and feeds.

Key Features

• M42 cobalt construction for improved heat and wear resistance over standard M2 HSS
• Double-end design provides two usable cutting ends, extending tool life per piece
• 30-degree right-hand spiral helix promotes efficient chip evacuation
• Centercutting geometry permits direct plunge entry without a pilot hole
• Uncoated finish suitable for use with cutting fluids on a broad range of workpiece materials
• 2-flute configuration leaves adequate chip clearance for slotting in softer and gummy materials

Compatibility

Designed as a standard-fitment replacement or stock end mill for 3/8-inch collet chucks and end mill holders requiring a 0.25-inch diameter, 2-flute cobalt square end mill in the OSG Series 522 family.

Installation Notes

Installation requires a milling machine with a properly sized collet or end mill holder matched to the 0.375-inch shank. Secure the shank to the full recommended grip depth and verify runout with a dial indicator before cutting. Always bring the spindle to a full stop before tool changes and inspect both cutting ends for chipping or wear before each use. Follow machine manufacturer guidelines and applicable shop safety standards when setting speeds, feeds, and depth of cut.