If you have ever worked on anything related to fasteners, such as bolts, screws, or studs, you may have encountered the process of tapping. 

Tapping allows for the installation of threaded fasteners by cutting or forming threads into a pre-drilled or stamped hole. From automotive to aerospace to construction, this is an important process across several industries. The following blog will discuss some of the basics, including various configurations and common use cases.

Basically, tapping depends on a tool known as (yes, guessed it right) a tap. A tap has threads coiling around its body on a helix and acts like a cutter. When inserted into a precisely sized hole, it cuts out the metal and creates matching threads. 

Sounds simple enough? Well, not quite.

Tap configurations and materials.

There are many different types of taps made to suit various materials, thread sizes, and purpose. Some common types of taps are:

  • Hand taps: The traditional tapping tools are turned manually by the use of a tap wrench or handle. It is excellent for simple threading on many materials.
  • Machine taps: These taps are meant to be used in machines/lathes that have robust cutting edges for harder materials.
  • Roll form taps: They do not cut the material but rather displace it under enormous pressure that creates threads.

Moreover, taps can be differentiated by the pitch (threads per inch) and whether they have straight or tapered/pipe threads. Furthermore, they are made from different materials such as high-speed steel, carbon steel, or carbide, just to mention a few.

So, with all those options, how do you know which tap to use? It depends on the material being tapped and the required thread strength. Softer materials like plastic, aluminum, or brass can get by with less aggressive taps. Harder metals need taps with precisely ground-cutting edges.

The right technique for tapping

Choosing the right tap is only half the battle. The second half is the proper tapping technique. You want to achieve good threads without damaging the tap or workpiece.  The following are some key principles:

  • Use appropriately sized and chamfered holes right from the beginning. This will avoid breaking taps by tapping into under-sized holes.
  • In soft materials like plastics, use cutting fluid/lubricant. This reduces friction and heat build-up.
  • Use slow to moderate speeds while applying constant and firm pressure on the tap. Going too fast may result in binding.
  • Back the tap out 1/4 turn periodically to break chips and clear threads.

Getting it right pays off. Improperly formed threads strip out, back off, or cross-thread when assembling fastened joints. This is not ideal when those threads are responsible for holding something together.

Uses & applications

Why go through all this trouble? What’s the use of tapping in real life?

The answer: pretty much everywhere threaded fasteners are involved.

In manufacturing, tapping allows internal threads to be easily added to parts and components using standard fasteners. Doing this gives strong, reusable threaded joints without the need to cast or mold the threads directly into the part material. Some examples include:

  • Tapped holes in engine blocks for inserting core plugs, fittings, and sensors
  • Threaded holes in brackets, fixtures, and machinery housings
  • Creating internal threads for plumbing fittings and pipe connections
  • Adding threaded holes electrical boxes or conduit

In construction and assembly too, threading is important when it comes to forming thread holes on materials such as steel beams, concrete anchors or large structural members.Tapped threads distribute heavy loads over a larger area.

In addition, consumer products also require tapping. It includes everything ranging from household furniture to electronic gadgets. Almost all would have started as ordinary holes which were tapped out to accept threaded bolts or screws.

Wrapping up

It is not always easy to see the importance of tapping, but try to think about a world without it. We would either have to look for alternative methods of assembly or have so many more individual part numbers to cover every variation on internally threaded components.

Actually, after any machining or forming process, virtually any material can be tapped with ease. This adaptability facilitates cheaper designs, less complicated part maintenance/replacement, and powerful reusable threaded connections across innumerable applications.

Although not the most glamorous of processes, it is essential for anyone who works with threaded fasteners to learn the essentials of tapping. With the right taps, techniques, and some practice, you will soon be threading like a pro yourself.