Understanding the Use of a Tap

The question asks about the primary function of a tool called a tap. Let's analyze the options to determine the correct use of a tap in threading operations.

What is a Tap?

A tap is a threading tool specifically designed to cut or form a thread inside a hole. This process is known as tapping. Taps are essential for creating internal screw threads, allowing bolts or screws to be fastened into materials.

Analyzing the Options

• Option 1: Cleaning external thread - This is typically done using a thread chasing tool or sometimes a die used backward, not a standard tap. A tap is for internal threads.
• Option 2: Forming external thread - External threads (like those on a bolt) are created using a die, not a tap.
• Option 3: Forming internal thread - This is the precise purpose of a tap. It is used to cut or form helical grooves on the inside surface of a hole, creating an internal screw thread.
• Option 4: Forming thread on nipple - A nipple usually has external threads. Forming external threads is done with a die.

Based on the functions of common threading tools, the correct use of a tap is to form internal threads.

Detailed Explanation: Forming Internal Threads

When you need to create a thread inside a drilled hole so that a screw or bolt can be threaded into it, you use a tap. The tap has cutting edges designed to progressively remove material from the inside of the hole as it is turned. Taps are often used in sets (taper, plug, and bottoming taps) for through holes or specific applications, although for some materials or less precise threads, a single tap might be sufficient.

Tap vs. Die

It's helpful to understand the difference between a tap and a die, as they are both common threading tools but serve opposite purposes.

Therefore, a tap is used for creating internal threads, while a die is used for creating external threads.

Conclusion on Tap Usage

The function of a tap is specifically to create internal threads within a hole. This makes option 3 the correct description of a tap's use.

Revision Table: Threading Tools

Additional Information on Tapping

Tapping requires careful technique to avoid breaking the tap or damaging the thread. Key considerations include:

• Using the correct size tap for the drilled hole (the tap drill size).
• Using appropriate cutting fluid or lubricant.
• Turning the tap gradually, often with a tap wrench.
• Clearing chips frequently by reversing the tap briefly.
• Keeping the tap aligned straight with the hole.

The internal thread created by tapping allows components to be securely fastened together.