Cleveland C55321 Spiral Point Tap 5/16-18 Unc Tin Hss

Product Description

The CLEVELAND C55321 is a spiral point tap designed for through-hole threading in metalworking applications. Built from high speed steel (HSS) with a titanium nitride (TiN) coating, it produces clean, accurate threads in cast iron and steel. The plug chamfer style provides a gradual cutting action suited for through-hole work. It cuts a 5/16-18 UNC right-hand thread to a Class 2B fit with an H3 thread limit, delivering consistent thread geometry across production and maintenance applications. Licensed machinists, tool-and-die technicians, and maintenance mechanics rely on this tap for both manual and machine tapping operations.

This tap is used in through-hole threading applications on ferrous materials including cast iron and steel. The 3-flute spiral point design pushes chips ahead of the cutting edge, keeping the flutes clear during machine tapping. It is well suited for production environments as well as maintenance and repair operations (MRO) where 5/16-18 UNC threads are a standard fastener size. The TiN coating extends tool life by reducing friction and wear at the cutting edge.

Key Features

• Spiral point geometry pushes chips forward, ideal for through-hole tapping
• TiN coating reduces friction and extends tool life in ferrous materials
• High speed steel construction handles both manual and machine tapping
• Plug chamfer for gradual thread engagement in through-hole applications
• H3 thread limit and Class 2B fit for standard UNC tolerance requirements
• Right-hand thread direction, 3 flutes, no coolant-through design

Compatibility

Designed for through-hole threading of 5/16-18 UNC threads in cast iron and steel workpieces. Compatible with standard tap holders and machine tapping heads sized for a 0.318-inch shank diameter.

Installation Notes

Machine or hand tapping should be performed by a qualified machinist or maintenance technician familiar with proper speeds and feeds for HSS taps in ferrous materials. Secure the workpiece fully before starting and confirm the tap holder or chuck is concentric to the hole axis to prevent tap breakage. Apply cutting fluid appropriate for the workpiece material. Never reverse a spiral point tap under power without verifying the machine supports reverse-feed tapping.