Osg 1230808 Spiral Point Tap 5/16-18 Unc Ticn Hss

Product Description

The OSG 1230808 is a spiral point tap designed for cutting right-hand internal threads in a wide range of ferrous and non-ferrous materials. Built from high-speed steel with a titanium carbonitride (TiCN) coating, this tap handles production threading in aluminum, cast iron, low-carbon, medium-carbon, and high-carbon steels. It features a plug chamfer and H3 thread limit, making it well suited for through-hole applications where chip flow is pushed ahead of the cutting edge. Overall length is 2.719 inches with a thread length of 0.724 inches (1-1/8 inches nominal). The 5/16-18 UNC profile is cut to a 3B class of fit, meeting standard tolerances for general fastener applications.

This tap is intended for machine tapping operations in job shop, production, and maintenance environments. The spiral point geometry drives chips forward and out of the hole, reducing the risk of chip packing in through-hole threading. It is suited for use in CNC machining centers, drill presses, and tapping machines. Typical applications include threading structural steel components, aluminum castings, and carbon steel workpieces where a 5/16-18 UNC fastener will be installed. Coolant-through is not supported, so external flood or mist coolant should be applied at the cutting zone during production runs.

Key Features

• 5/16-18 UNC thread form with H3 thread limit for consistent 3B class of fit tolerances
• High-speed steel construction provides toughness across a broad range of workpiece materials
• TiCN coating reduces friction and heat buildup, extending tool life in steel and cast iron
• Plug chamfer (3-5 thread lead) optimized for through-hole tapping
• Spiral point geometry pushes chips forward to keep flutes clear during cutting
• Right-hand thread direction; no coolant-through requirement simplifies setup

Compatibility

Designed for through-hole tapping of 5/16-18 UNC threads in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, high-carbon steel, and hardened steel workpieces.

Installation Notes

This tap is installed and used by machinists and tool-and-die professionals in machine tapping applications. Always secure the workpiece and ensure the spindle is aligned with the hole centerline before engaging the tap. Use appropriate cutting fluid or coolant for the workpiece material to prevent galling and premature wear. Inspect the tap for chipping or wear before each production run, and replace at the first sign of torque increase or thread quality degradation.