A Practical User’s Guide to Carbide Taps

North American Tool offers carbide taps in UN and Metric sizes as well as straight and NPT/F Pipe and STI Standards. A wide range of styles and features, including straight flute, spiral flute, spiral point, and forming taps are available, as well as a full line of surface coatings such as TiN, TiCN, and TiALN for increased performance and life.

So, why carbide? Or more to the point, when carbide?

Let’s consider hard or difficult materials. Where high speed steel taps have a practical top limit of around 35-­40 HRC before tap life becomes severely limited, carbide is often used in materials with hardness up to 65 HRC. Carbide is most effective in highly abrasive materials like cast iron, polymers, glass filled polycarbonates, and some cast aluminum (materials that chew up HSS in no time). With the appropriate style for the application, tool life of carbide can be 5­20 times that of HSS, with superior accuracy.

Of course, machining with carbide does not come without its precautions. Hand­tapping is generally not recommended.  Rigid tapping and spot­on alignment is critical to avoid breakage.  Modern CNC equipment is ideally suited for carbide applications.

Although initially more expensive than high-speed steel taps, significant savings can be realized, especially in long­run jobs. Higher cutting speeds, greater tool life, and reduced down­time from fewer tooling changes translate into reduced machining costs.

Coolant holes through the taps are an option for flushing chips out of the holes on the most difficult materials like some of the tougher stainless steels and space-­age alloys. Carbide STI (Screw Thread Insert) tapping of these materials has become commonplace in the aeronautical and aerospace industries.

An alternative to costly larger sizes is North American Tool’s line of Carb­I­Sert® Taps.

Solid carbide cutting surfaces are bonded onto a high-speed steel body to provide the best of both worlds; durability of carbide with the “forgiveness” of a steel body and shank.

North American Tool’s carbide taps are American made from high-quality C2 micro-grain carbide by highly skilled machinists on state ­of ­the art equipment and are backed by decades of experience from our support staff.