A tap refers to a cylindrical or conical thread-cutting tool with threads of a specific shape around the periphery. Metal cutting taps remove internal threads from parts of machinery and products. The tap creates the internal thread by combining rotational and axial action.
The Technique of Threading Taps
The soft and hard machining of a tap is distinguished fundamentally. The blank is initially turned into a fundamental shape while still soft, and after the square is machined, the blank is tempered and hardened.
The hardening process aims to increase mechanical resistance through targeted change and transformation of the microstructure. The blank is heated, chilled, then heated once again.
The tap's hard machining process starts after hardening. A flute grinding machine is used to mill flutes and finish the thread. Modern machine tools combine clamping for thread grinding and chamfer grinding, and the tap is finally marked.
The tap's quality is determined by the production processes and the raw materials used. Significant quality disparities are particularly evident in the following areas:
- A low-quality substance is treated
- The blank is improperly hardened and tempered
- The thread is only round-ground and not relief-ground
- The rake angles are incorrect, contributing to the tap's failure to cut or rapid wear
Types of Taps
Knowing when to utilize each of the many distinct thread tap kinds will help you tap threads more quickly and efficiently.
Spiral Flute Taps
Similar to an endmill, spiral flute taps have an open spiral. Their most significant advantage is releasing chips up and out of the hole. When there is a blind hole, they are always better than spiral point taps.
Additionally, because the spiral aids in resuming the threading past the exposed feature, they are preferred for interrupted holes where another feature meets.
Take a spiral flute tap and a standard hand tap occasionally, and tap a few identical holes by hand. You'll be surprised how much less work is needed when using the spiral flute tap.
Since a bottoming tap is made to thread to the bottom of its reach, there is almost no taper at the end. There will only be a 1 to 1.5-thread taper. Blind holes can be threaded with the assistance of bottoming taps. It is preferable to use a taper tap to thread most of the hole before a bottoming tap completes the bottom.
A taper tap features a substantial degree of taper to cut threads gently. In most cases, the first eight to ten threads are tapered. The most frequent taps are taper taps, and a tap and die set will usually include some of these taps.
Interrupted Thread Tap
There is just one tooth for every other thread on these thread taps. The goal is to offer better chip extraction. Every other tooth is removed, which aids chip breaking and creates more space for lubricant to enter and perform its function and more area for the chip to exit.
Pipe Taps are the categories of thread taps used to tap pipe threads. Depending on whether the pipe thread is meant to be straight or tapered, there are both straight and tapered pipe taps available.
Because a tapered hole cannot be drilled, taps for tapered pipe threads must work harder. They need to remove more material from the top of the hole than the bottom. To make the hole taper, use a pipe taper reamer so the tap doesn't have to work as hard.
Thread Forming Taps
Thread-forming taps do not cut threads; they coldly form instead. This method of making threads is known as "rolling threads.". Instead of being sliced, the metal is pushed out of the way and squeezed into place using this method, as nothing needs to be chipped away. As a result, the threads produced by the taps are stronger than the taps themselves.
Form taps are typically the best option if your application supports them. Be mindful of this before utilizing a form tap, as they require various feeds, speeds, and initial hole sizes.
Making the right tap choices is essential. At SCTools, we have tools that allow you to do precise and accurate metal bending and threading operations.
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