Drilling Machine Operations

Primary operation of drilling machine is to cut straight blind or through holes in a specimen/part. But drilling machines are also used for other operations as well.

In this article we will discuss major operations carried out by drilling machine.

Drilling

Drilling is metal cutting operation by rotating and pressing multi point cutting tool to cut a circular straight hole in solid materials.

Multi-point cutting tool is known as drilling bit.Standard drill bits in different size are available.

Drilling operation involves rotation of drill bit at high speed.

Reaming

Reaming is a cutting and finishing operation. It enlarges existing hole diameter to make it more accurate and improves surface finish. 

Speed of spindle during reaming is approx. kept half of the speed during drilling operation.

Tapping Operation

Tapping is a thread cutting operation inside a hole. in another words, It is used to make internal threads in existing hole.

Tapping operation can be done with hand tool or by using drilling machine. For tapping spindle speed is kept low.

With this operation we can save extra part and  blind assembly is also possible.

Boring

Boring is a metal cutting operation for enlarge existing hole diameter. Tool bit is a single point edge cutting tool. Speed of spindle is kept relatively less during boring operation.

Counter-boring 

Counter-boring is a metal cutting operation for making a stepped hole. During counterboring a relatively larger diameter hole is drilled in smaller hole axis.

It’s application is to flush fasteners head with part surface. Drill tool bit can also be used for counterboring operation.

Countersinking

Countersinking is a metal cutting operation for making a cone shaped enlargement at the start of already drilled hole. Angle of the conical surface depends on the requirements.

Its’s application is to provide recess to a Counter sunk fastener. Drill tool bit can also be used for countersink operation. 

Spot Facing

Spot facing is a small height counterbore.  Application of spot facing is  to face the area where bolt or nut has to sit. It is done to provide adequate seating to a fastener.

In another words spot facing is a counterbore but the counterbore is not a spot face.

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