Osg 5818300 Square End Mill 0.2165 in 4 Flute Cobalt

Product Description

The OSG 5818300 is a 4-flute cobalt square end mill engineered for milling operations in ferrous and high-temperature alloy materials. Built from M42 cobalt high-speed steel, it delivers good wear resistance and heat tolerance compared to standard M2 HSS tooling. The cutter measures 0.2165 inches in diameter with a 9/16 inch length of cut, a 3/8 inch shank diameter, and a 2-7/16 inch overall length. A 30-degree right-hand spiral flute geometry promotes chip evacuation and smooth cutting action. This is a non-centercutting design, meaning it is intended for peripheral and side milling rather than plunge entry. Machinists and tool-and-die professionals are the primary users of this tool.

The OSG 5818300 belongs to the Series 581 regular-length square end mill line. It is suited for slotting, profiling, and step milling applications on CNC machining centers and manual knee mills. The 0.2165 inch cutting diameter corresponds to the 5.5 mm metric equivalent, making it a useful crossover tool in shops running both inch and metric programs. The uncoated cobalt construction is well matched to stainless steel, tool steels, and cast iron where coated carbide may not be the preferred choice. This tool is not designed for plunge cutting due to its non-centercutting configuration.

Key Features

• M42 cobalt high-speed steel construction for elevated heat and wear resistance
• 4-flute spiral design with 30-degree right-hand helix for efficient chip removal
• 0.2165 inch (5.50 mm) cutting diameter with 9/16 inch length of cut
• 3/8 inch shank diameter fits standard ER and straight-bore toolholders
• Right-hand cut, right-hand flute, uncoated finish — no regrind coating required
• Non-centercutting geometry — designed for peripheral and side milling only
• Regular length (Series 581) for general-purpose rigidity in typical reach applications

Compatibility

Designed as an OEM-style replacement or direct-use square end mill fitting any standard 3/8 inch straight-shank toolholder or collet chuck. Specific machine or system compatibility was not stated in the product data.

Installation Notes

Installation should be performed by a qualified machinist following the machine tool manufacturer's toolholding torque and runout specifications. Always power down and lock out the spindle before mounting or removing the end mill. Confirm shank seating depth and collet or chuck concentricity before beginning a cut. Because this tool is non-centercutting, do not use it for direct plunge entry into solid material.