Wednesday, 29 December 2021

Tools used in a drilling machine

Different tools are used for performing different types of operations. The most commonly used tools in a drilling machine are 

1. Drill 
2. Reamer 
3. Counter bore 
4. Countersink 

Drill 
A drill is a tool used to originate a hole in a solid material. A helical groove known as ‘flute’ is cut along the length of the drill. Different types of drills are 
 1. Flat Drill 
 2. Straight fluted drill 
 3. Twist drill 
 4. Centre drill 
twist drills are the type generally used in shop work. They are made of High speed steel (HSS) or High carbon steel. There are two types of twist drills namely 
(i) Straight shank twist drill and 
(ii) Taper shank twist drill. 
The diameter of the straight shank drill ranges from 2 to 16mm. Taper shanks is provided on drills of larger diameter.

Reamer 
The tool used for enlarging and finishing a previously drilled hole is known as a reamer. It is a multi tooth cutter and removes smaller amount of material. It gives a better finish and accurate dimension.
 
Counter bore 
A Counter bore is a multi tooth cutting tool used for enlarging the top of the previously machined hole. It has three or four cutting teeth. The flutes on them may be straight or helical. Straight fluted tools are used for machining softer materials like brass and aluminium and for short depth of cut. Helical fluted types are used for longer holes.

Countersink 
A countersink has cutting edges on its conical surfaces. It has a similar construction of a counter bore except for the angle of the cutting edges. The angle of countersinks will generally be 60°, 82° or 90°. It is used for enlarging the top of the holes conically.

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