What Tapping Is For and How to Use a Tap

Creating good threading on metal is fundamental to completing good mechanical work and to recover situations that require the use of pins and bolts. In these dynamics, however, it's right to deepen the topic of tapping and the corresponding use of appropriate tools. That is, the tap wrench, the tool that allows you to create threads in holes.

This is what we're talking about: tapping is the threading that is activated through a series of fundamental steps. But above all, with appropriate tools like tap wrenches. Like those you find in the Krino catalog that can also be activated manually.

What Is Tapping and What Does It Do?

By the term tapping, we mean a process of internal threading that is performed through a specific tool known as a tap. Which can be machine or manual. All of this concerns the process of internal threading of a hole that can be performed in a metal block or in a bolt. Which perhaps in the past has been damaged, ruining the threading.

What Are Taps for Tapping?

The operation is performed with tools known as taps: tools with an elongated shape, similar to a drill bit, made of steel suitable for mechanical machining to cut in such a way as to create a thread with a determined pitch.

The cutting edges of the tap remove the metal component by cutting, except in the case of thread rolling where the material (particularly ductile) is deformed. In some cases, taps are coated with a layer of titanium to increase durability over time (what is and what is the TiN coating for). But what does a tapping tool look like? On one side there is the shank that allows you to attach the tool to the manual tap wrench or to the tool holder for an automated machine.

The flutes are characterized by grooves that allow chips to exit: straight solutions are suitable for generic uses, helically shaped ones are used for materials that produce long chips. The entrance is designed to allow entry into the hole, so it has a slightly smaller diameter that leads to the first flutes that create the tapping work.

There are also different types of taps: those with short or long entrance. The former are perfect for blind holes since they can easily reach the bottom, the latter are used for through holes since they simplify chip removal. Then there are roughing, intermediate, and finishing taps for work that requires multiple passes. Of course, these taps must be used in the right way.

How to Tap with the Tap Wrench

First of all, it's essential to drill a hole in the metal that has a diameter smaller than that required for tapping. You choose the tap suitable for the type of work – according to Wikipedia, the rake angle will be between 5° and 10° for hard steel, higher values for less tough metals like aluminum, cast iron, and brass – and insert it in correspondence with the hole. With the tap wrench, then, proceed with a continuous clockwise movement. In this video you can watch a tutorial using exactly a set of Krino taps.

The tap remains vertical and perpendicular to the hole, in roughing – the first pass, two complete clockwise turns and one counterclockwise turn are made to break the chip. All of this should be facilitated by a few drops of cutting oil for metal cutting. To deepen the topic, there is a guide dedicated specifically to cutting and drilling oil, a guide to effective use.