Drilling and Reaming
Introduction
- Drilling may be defined as the operation of producing a hole by removing metal from the solid mass using a cutting tool called Drill.
- Reaming is the operation of sizing and producing a smooth round hole from a previously drilled or bored hole with the use of a cutting tool having several cutting edges. Reamer is a rotary cutting tool with several straight or helical cutting edges along its body. It is used to accurately size and smooth a hole which has been previously drilled or bored. Some reamers are operated by hand called Hand Reamers are finishing tools used when a hole must be finished to a high degree of accuracy and finish. Holes to be hand reamed should be bored to within 0.07 mm to 0.12 mm; While others may be used under power in any type of machine tool are called Machine Reamers.
- Countersinking is the operation of producing a tapered or coned-shaped enlargement to the end of a hole with the tool called countersink.
- Counterboring is the operation of enlarging the top of a previously drilled hole to a given depth to provide a square shoulder for the head of a bolt or capscrew, and the tool called counterbore.
- Spot Facing is the operation of smoothing and squaring the surface around a hole to provide a seat for the head of a cap screw or a nut.