Osg 5310400 Square End Mill 5/16 in 3 Flute Cobalt

Product Description

The OSG 5310400 is a cobalt square end mill designed for milling ferrous and difficult-to-machine materials where high-speed steel tooling falls short. Built from M42 cobalt high-speed steel, it offers superior heat and wear resistance compared to standard HSS. The cutter measures 5/16 inch in diameter with a 3/4 inch length of cut and a 3/8 inch shank diameter, yielding an overall length of 2-1/2 inches. The three-flute, 30-degree spiral geometry balances chip evacuation with edge strength. This is a centercutting tool, meaning it can plunge directly into a workpiece. Machinists and tool and die professionals use this end mill for slotting, profiling, and contouring operations.

The OSG 5310400 belongs to the Series 531 line and is suited for job shop and production environments where cobalt tooling is specified for alloy steels, stainless steels, cast iron, and similar materials. The regular length geometry and right-hand cut with right-hand flute configuration make it a straightforward drop-in for standard vertical milling setups. It ships uncoated, which simplifies regrinding and keeps per-edge cost predictable for shops that resharpen tooling.

Key Features

• M42 cobalt construction for heat resistance and extended tool life in hard or abrasive materials
• Three-flute design balances chip clearance and cutting edge support
• 30-degree helix angle promotes smooth cutting action and reduced chatter
• Centercutting geometry allows direct plunge entry without a pre-drilled hole
• Spiral flute, right-hand cut and right-hand flute configuration for standard milling spindles
• Uncoated finish simplifies regrinding for shops that recondition end mills

Compatibility

Designed as an OEM-style tooling replacement for 3/8 inch collet or end mill holder setups commonly used in vertical mills, CNC machining centers, and manual knee mills requiring a Series 531 regular-length square end mill.

Installation Notes

Installation requires a properly sized collet, end mill holder, or Weldon-style set-screw holder accepting a 3/8 inch shank. Ensure the spindle is fully de-energized and locked out before changing tooling. Verify runout with a dial indicator after seating the tool to minimize premature wear. Follow the machine manufacturer's recommended speeds and feeds for cobalt tooling in the workpiece material being cut.