Types of Drilling Machine Operations: Boring, Reaming, Counter Sinking, Spot Facing, Tapping | Manufacturing Processes

In todays session we learn about drilling machine operations like drilling, reaming, boring, counter sinking, counter boring, spot facing, Tapping operations. so first is drilling operations, in drilling we produce a cylindrical hole inside workpiece. Here, material is removed by rotating edge of cutting tool. And that rotating edge is called a drill. in drilling internal surface of hole is usually rough, and the hole is always bigger than drill size. next is Boring Operation, here we increase the diameter of the hole which was previously produced. Boring operation is done due to machining internal surface of hole which was produced by casting process. Boring operation is done due to correcting roundness of hole and finishing the hole correctly and for making it of required size. The boring tool has only one cutting edge. The boring tool is placed in a boring bar which has a tapered shank. The speed of the spindle in the boring is usually very less than the reaming. the Spot Facing Operation is used for producing a flat seat for bolt head, washer or nut at the opening of drilled hole. it is used to give a high surface finish at the top of hole. next tapping operation, here tap is used for making internal threads which can be fit into external threads of identical size. That means here tap works as a cutting tool. Tapping operation can be performed by hand. Or you can also use any external power for doing this. In Counter Boring operation, the end of hole is enlarged cylindrically. here counterbore works as a tool. The counterbore consists of cutting edges. These cutting edges may be straight or spiral. The cutting speed in counterboring process is usually slow. this cutting speed is 25% smaller than that of speed in drilling. next is Reaming operation, here before Reaming the size of hole after drilling process may not be perfect. Most of time, its internal surface may not be finished properly. Reaming is done to obtain desired size of hole. Also, internal surface of hole gets appropriately finished with this process. here Reamer is used for reaming. Reamer is a multi-point cutting tool. the Counter Sinking operation is used to make coned shaped enlargement at end of hole. here included angle of conical surface may be 60 degree to 90 degree. A countersink tool has multiple cutting edges on its conical surface.