Osg 5403205 Square End Mill 7/8 in 4 Flute Cobalt Tin

Product Description

The OSG 5403205 is a 4-flute cobalt square end mill designed for milling ferrous and hard materials in machining centers and manual mills. Built from M42 cobalt high-speed steel, it carries a TiN (titanium nitride) coating that extends tool life and reduces friction during cutting. The mill diameter is 0.875 inches (7/8 inch), with a 1.875-inch (1-7/8 inch) length of cut and a 0.750-inch (3/4 inch) shank diameter. Overall length is 4.125 inches (4-1/8 inch). The 30-degree spiral helix and right-hand cut geometry promote efficient chip evacuation and stable cutting action across a range of feed rates and depths.

This end mill is suited for peripheral and slot milling operations on steel, stainless steel, and other ferrous alloys in both production shop and job shop environments. The regular-length body and standard shank diameter make it a common choice for side milling, profiling, and pocketing operations. It is a single-end, non-center-cutting tool, so plunge cuts are not recommended. Machinists and CNC operators working on general-purpose milling fixtures, dies, and machine components will find this a practical tooling choice.

Key Features

• M42 cobalt HSS construction for elevated heat and wear resistance compared to standard M2 HSS
• TiN finish reduces friction and extends tool life on ferrous materials
• 4-flute design balances chip clearance with surface finish quality
• 30-degree right-hand spiral flute promotes smooth chip flow and reduced cutting forces
• Non-center-cutting geometry — suited for peripheral, slot, and side milling, not plunge entry
• OSG Series 540 regular-length design for stable overhang and general-purpose fitment

Compatibility

Part of the OSG Series 540 regular-length end mill line. Designed for use in standard R8, CAT, BT, or equivalent toolholders accepting a 3/4-inch shank diameter. Verify toolholder runout and collet condition before use.

Installation Notes

Installation and tool changes should be performed by a qualified machinist with the machine powered down and the spindle fully stopped. Ensure the shank is clean and the toolholder collet or set screw is torqued to the toolholder manufacturer specification. This is a non-center-cutting end mill — do not use for direct plunge operations; use a drill or center-cutting end mill to establish an entry point first. Follow shop safety protocols and applicable OSHA machining guidelines when operating milling equipment.