Question

The machining operation used to enlarge an existing hole is termed as:

• A. Drilling
• B. Reaming
• C. Boring
• D. Counter sinking

Hint:

Think of it this way: Drilling makes the hole, reaming perfects the size and finish, boring makes it bigger and more accurate, and countersinking shapes the opening.

Answer 1

The Correct Option is C

Step 1: Understand the different hole-making and hole-enlarging machining operations.
Drilling: The process of creating a new hole in a solid material using a drill bit.
Reaming: A finishing operation used to enlarge an existing hole to a precise size and improve its surface finish. It removes a small amount of material.
Boring: A machining process used to enlarge an existing hole to a larger diameter with high accuracy and improve its internal finish. It can also be used to create truly cylindrical holes or to machine internal features.
Counter sinking: The process of creating a chamfer or a conical enlargement at the opening of a hole, often to accommodate the head of a countersunk screw or rivet.
Step 2: Analyze the question to identify the specific requirement.
The question asks for the machining operation used specifically to enlarge an existing hole. Step 3: Evaluate each option based on the definition and purpose of the operation.
Drilling: Creates a new hole, not enlarges an existing one.
Reaming: Enlarges an existing hole slightly, primarily for dimensional accuracy and surface finish. The amount of material removed is small.
Boring: Enlarges an existing hole to a larger diameter with high precision and can remove a significant amount of material.
Counter sinking: Modifies the opening of a hole by creating a taper; it doesn't primarily aim to enlarge the cylindrical portion of the existing hole.
Step 4: Identify the operation that primarily focuses on enlarging an existing hole.
Boring is the machining operation specifically designed to enlarge an existing hole to a larger size with accuracy. Step 5: Select the correct answer.
The machining operation used to enlarge an existing hole is termed as Boring.