Holes in a plate for rivetted joints is preferably made by

ANS:A - drilling

Drilling is a machining operation used to create holes in solid materials, such as metal, wood, or plastic. It involves the use of a rotating cutting tool called a drill bit, which applies a downward force while rotating to remove material and create a hole of the desired diameter and depth. Here's how the drilling process works:

1. Setup: The workpiece is securely clamped to a stable surface or placed in a vise to prevent movement during drilling. The drill bit is mounted in the chuck of a drill press or handheld drill.
2. Alignment: Proper alignment of the drill bit is essential to ensure that the hole is drilled accurately. This may involve marking the location of the hole with a center punch or layout dye and using guides or jigs to position the drill bit.
3. Drilling: The drill bit is brought into contact with the surface of the workpiece, and the drill press or handheld drill is activated to start the drilling process. As the drill bit rotates, its cutting edges remove material from the workpiece, creating the hole.
4. Chip Removal: During drilling, chips or swarf are formed as the drill bit cuts into the material. These chips are typically removed from the hole using flutes or grooves on the drill bit, which help to clear the debris and prevent clogging.
5. Coolant (optional): In some cases, especially when drilling hard metals or materials prone to overheating, a coolant or cutting fluid may be used to lubricate the drill bit and workpiece, dissipate heat, and prolong tool life.
6. Completion: Once the desired hole depth is achieved, the drilling operation is stopped, and the drill bit is retracted from the workpiece. The result is a clean, accurately sized hole ready for further processing or assembly.

Drilling is a versatile and widely used machining process, employed in various industries for applications ranging from simple DIY projects to high-precision manufacturing operations. It offers flexibility in hole size, depth, and material compatibility, making it an essential technique in the fabrication of many products.