Osg 1645056185 Spiral Flute Tap 5/16-18 Unc Tin Hss

Product Description

The OSG 1645056185 is a spiral flute tap designed to cut 5/16-18 UNC internal threads in a wide range of ferrous materials. Built from vanadium high-speed steel with a titanium nitride (TiN) coating, it delivers extended tool life and reduced friction during the tapping cycle. The modified bottoming chamfer allows threading close to the bottom of blind holes, making it well suited for tight-tolerance applications. With a 45-degree helix angle and right-hand flute direction, it efficiently evacuates chips upward out of the hole. Machinists and tool-and-die technicians working to a 2B class of fit will find it meets standard dimensional requirements for general mechanical assembly.

This tap is intended for use in CNC machining centers, manual mills, and tapping machines where 5/16-18 UNC threads are required in blind or shallow through-hole configurations. Its H5 thread limit makes it appropriate for production environments where consistent 2B fit tolerances are maintained across multiple parts. Material suitability includes alloy steel, cast iron, high-carbon steel, low-carbon steel, medium-carbon steel, and stainless steel. It is sold individually and is part of OSG Series 16450.

Key Features

• Modified bottoming chamfer for threading close to the bottom of blind holes
• 45-degree right-hand helix angle promotes upward chip evacuation in blind-hole applications
• TiN coating reduces friction and extends tool life in ferrous materials
• Vanadium high-speed steel construction provides toughness and wear resistance
• H5 thread limit holds consistent 2B class of fit tolerances
• 3-flute design balances chip removal with tool rigidity at this thread size

Compatibility

Suited for tapping 5/16-18 UNC threads in alloy steel, cast iron, high-carbon steel, low-carbon steel, medium-carbon steel, and stainless steel workpieces. Designed for use in standard tap holders and collet chucks accepting a 0.318-inch shank diameter.

Installation Notes

Installation should be performed by a qualified machinist following standard tapping procedures for the workpiece material. Secure the tap in a properly sized tap holder or rigid collet chuck before operation; avoid excessive runout, which can break taps at this diameter. Apply appropriate cutting fluid for the workpiece material to extend tool life and improve thread finish. Always bring the spindle to a full stop before inspecting the tap or removing the workpiece.