Osg 1120708 Straight Flute Tap 5/16-18 Unc Ticn Hss

Product Description

The OSG 1120708 is a straight flute tap designed for cutting 5/16-18 UNC internal threads in a wide range of ferrous and non-ferrous materials. Built from high-speed steel (HSS) with a titanium carbonitride (TiCN) coating, it delivers increased surface hardness and wear resistance compared to uncoated HSS taps. The plug chamfer (3-5 threads) allows the tap to start easily and distribute cutting load gradually. With an H3 thread limit and a 3B class of fit, the 1120708 produces threads to tighter tolerances, making it suitable for applications where fit and fastener engagement matter. Machinists and toolroom technicians install this tap in manual or CNC tapping setups.

This tap is suited for threading operations in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. The straight flute design makes it appropriate for through-hole and blind-hole applications in materials that produce short, chippy chips. It performs in production environments and job shop settings alike, where consistent 5/16-18 UNC thread quality is required across a range of part materials.

Key Features

• 5/16-18 UNC thread form with right-hand thread direction
• 4-flute straight flute design for stable cutting in short-chipping materials
• Plug chamfer for gradual thread engagement and easy starting
• TiCN coating improves wear resistance and tool life over uncoated HSS
• H3 thread limit with 3B class of fit for consistent, tolerance-controlled threads
• No coolant-through requirement - compatible with standard flood or mist coolant setups

Compatibility

Designed for use in aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel applications requiring 5/16-18 UNC internal threads to a 3B class of fit.

Installation Notes

Installation should be performed by a qualified machinist following standard tapping procedures. Ensure the workpiece is properly fixtured and the tap is aligned perpendicular to the hole before engagement. Use appropriate cutting fluid for the workpiece material to extend tool life and improve thread surface finish. Never reverse-cycle a tap under load without first relieving chip pressure, and do not force the tap if resistance increases unexpectedly.