Hertel K008391AS25 Spiral Point Tap 5/16-18 Unc Tin Hss

Product Description

The HERTEL K008391AS25 is a spiral point tap designed for threading 5/16-18 UNC through-holes in a wide range of materials. It features a plug chamfer, two flutes, and a TiN (titanium nitride) coating over a high-speed steel (HSS) body. The spiral point geometry pushes chips forward ahead of the tap rather than packing them in the flutes, making it well-suited for through-hole applications where chip evacuation is critical. The H3 thread limit provides consistent fit to a 3B class of fit tolerance. This tap is right-hand cut and is installed without coolant-through capability. Machinists, tool-and-die workers, and maintenance technicians use this tap in drill press, CNC, and hand-tapping operations.

This tap is appropriate for threading 5/16-18 UNC through-holes in steel, aluminum, cast iron, and similar materials encountered in general manufacturing, maintenance and repair, and fabrication environments. The plug chamfer style requires a starter hole and is the standard choice when tapping through-holes where the tap can exit the opposite side. The TiN coating extends tool life by reducing friction and increasing surface hardness compared to uncoated HSS taps. It is well-suited for production runs as well as single-use maintenance applications in both shop and field settings.

Key Features

• Spiral point geometry pushes chips forward for reliable through-hole tapping
• TiN coating reduces friction and extends tool life versus uncoated HSS
• High-speed steel construction handles a broad range of workpiece materials
• Plug chamfer for standard through-hole entry and full thread engagement
• H3 thread limit holds 3B class of fit tolerance for consistent thread quality
• Right-hand cut, no coolant-through required

Compatibility

Designed as an OEM-style replacement or direct-use tap for 5/16-18 UNC through-hole threading applications. Compatible with standard tap holders, drill presses, CNC tapping heads, and hand-tapping drivers that accept this shank size.

Installation Notes

This tap is installed by licensed machinists or qualified maintenance technicians using a tap wrench, drill press, or CNC tapping attachment. Ensure the workpiece is securely clamped and the pilot hole is drilled to the correct tap drill diameter for 5/16-18 UNC before beginning. Apply appropriate cutting fluid for the workpiece material to prevent galling and extend tap life. Reverse the tap periodically when hand-tapping to break chips and prevent tap breakage.