Hertel 008380AS25 Straight Flute Tap 5/16-18 Unc Hss Tin

Product Description

The HERTEL 008380AS25 is a straight flute tap designed to cut 5/16-18 UNC internal threads in through-holes and shallow blind holes where chip control is managed by the operator. Built from high-speed steel (HSS) with a titanium nitride (TiN) coating, this tap delivers improved surface hardness and lubricity compared to uncoated HSS, extending tool life in moderate-production threading applications. The plug chamfer (3-5 threads of lead) provides a balanced entry suitable for most standard through-hole and blind-hole work. With a thread limit of H3, it holds a 3B class of fit, meeting standard commercial tolerance requirements. Licensed machinists and maintenance technicians are the primary users.

This tap is suited for threading ferrous and non-ferrous materials in job shop, maintenance, and production environments. The 5/16-18 UNC designation makes it a common choice for general mechanical assembly, repair work, and fabrication tasks where 5/16-inch fasteners are specified. It is used in both manual tapping handles and low-speed machine tapping setups. The right-hand thread direction is standard for the vast majority of fastener applications. With a thread length of 1-1/8 inches and an overall length of 2-23/32 inches, it fits standard tap holders without modification.

Key Features

• 5/16-18 UNC thread form with H3 thread limit for 3B class of fit
• Plug chamfer provides 3-5 thread lead-in for versatile through-hole and blind-hole use
• High-speed steel construction for toughness across a range of workpiece materials
• Titanium nitride (TiN) coating increases surface hardness and reduces friction at the cutting edge
• 4 straight flutes with right-hand thread direction
• No coolant-through requirement — compatible with hand tapping and standard machine tapping

Compatibility

Designed as a standard replacement or production tap for any application requiring a 5/16-18 UNC right-hand internal thread with a 3B class of fit in standard tap handles or machine tap holders.

Installation Notes

Secure the workpiece before tapping and ensure the correct tap drill size for 5/16-18 UNC is used prior to starting this tap. Apply cutting fluid appropriate to the workpiece material to reduce heat buildup and extend tap life. When machine tapping, use a low spindle speed and a tapping attachment with torque relief to avoid overloading the tap. Inspect the tap for wear or chipping before each use and discard if the cutting edges are compromised.