Correct Answer - Option 3 : finishing an existing hole surface
Explanation:
Reaming removes a small amount of material from the surface of holes. It is done for two purposes:
1. To bring holes to a more exact size
2. To improve the finish of an existing hole
Boring: Boring is an operation to enlarging of an existing hole, which may have been made by a drill or maybe the result of a core in a casting.
Drilling: Drilling is a cutting process that uses a drill bit to cut or enlarge a hole of circular cross-section in solid materials. The drill bit is a rotary cutting tool.
Reaming: Reaming is a sizing operation that removes a small amount of metal from a hole already drilled. It is done for two purposes: to bring holes to a more exact size and to improve the finish of an existing hole.
Drilling is used to cut or enlarge the diameter. Reaming operation is meant to slightly increase the size and to provide a better tolerance and surface finish of an initially drilled hole.
