Hertel K010314AS25 Thread Forming Tap 4-40 Unc Plug Hss Tin

Product Description

The HERTEL K010314AS25 is a plug-chamfer thread forming tap designed for right-hand, through-hole threading in 4-40 UNC applications. Built from high-speed steel (HSS) with a titanium nitride (TiN) coating, this tap forms threads by displacing material rather than cutting it, resulting in stronger threads and no chips to clear. It carries an H3 thread limit and fits Class of Fit 2B and 3B tolerances. Overall length is 1.875 inches with a thread length of 0.5625 inches and a shank diameter of 0.141 inches. Installed by machinists and maintenance technicians in production and repair environments.

This tap is suited for through-hole threading in soft to medium-hardness materials where chip evacuation is a concern or where thread strength is a priority. The plug chamfer features 3 to 5 chamfered threads, making it appropriate for starting in an existing hole or continuing a thread sequence in a through-hole setup. Typical applications include threading small-diameter fastener holes in metal components, fixtures, and assemblies that require 4-40 UNC hardware. The TiN coating extends tool life and reduces friction during the forming operation.

Key Features

• Thread forming (chipless) design produces stronger threads and eliminates chip buildup in through-holes
• Titanium nitride coating reduces friction and extends tool service life
• High-speed steel construction handles a wide range of workpiece materials
• Plug chamfer with 3 to 5 chamfered threads for controlled thread entry
• H3 thread limit with 2B and 3B Class of Fit for standard UNC tolerance requirements
• Right-hand thread direction, 4-40 UNC specification

Compatibility

Designed for through-hole threading operations requiring 4-40 UNC right-hand threads with a 2B or 3B Class of Fit. Compatible with standard tap wrenches and machine tap holders sized for a 0.141-inch shank diameter.

Installation Notes

Thread forming taps require a specific forming tap drill size - do not use a standard cut-tap drill chart, as forming taps need a larger pilot hole than cutting taps of the same thread designation. Secure the workpiece fully before tapping and apply appropriate tapping fluid for the workpiece material. Use in a tapping machine, drill press, or rigid setup to maintain axial alignment and avoid tap breakage. Follow applicable shop safety practices and manufacturer speed recommendations for HSS taps in the target material.