The drilling tools called drills are used for making round holes in the work. The following types of drills are commonly used :-
1. Flat drill- It is a simple type of drill and has two cutting edges bevelled at 60°
2. Straight fluted drill- It is used for making holes in brass, copper and other soft metals. It is considered as a cutting tool having zero rake.
3. Twist drill- It is an end cutting tool with two, three or four cutting lips. It has a cylindrical body on which the grooves are cuts. These grooves are called flutes. While drilling, the drill is held by a shank. The shank may be parallel or tapered .
The parallel shank is provided on small sized drills (I.e. foto 12.5mm). The tapered shank drills have a taper called Morse taper. The twist drills are made of either carbon steel or high speed steel. It is specified by its shank ,material and diameter. The various angle of the twist drill are as follows:-
1.Point angle
2.Lip relief (clearance)
3.Chisel edge angle.
4.Helix or rake angle.
1. Flat drill- It is a simple type of drill and has two cutting edges bevelled at 60°
2. Straight fluted drill- It is used for making holes in brass, copper and other soft metals. It is considered as a cutting tool having zero rake.
3. Twist drill- It is an end cutting tool with two, three or four cutting lips. It has a cylindrical body on which the grooves are cuts. These grooves are called flutes. While drilling, the drill is held by a shank. The shank may be parallel or tapered .
The parallel shank is provided on small sized drills (I.e. foto 12.5mm). The tapered shank drills have a taper called Morse taper. The twist drills are made of either carbon steel or high speed steel. It is specified by its shank ,material and diameter. The various angle of the twist drill are as follows:-
1.Point angle
2.Lip relief (clearance)
3.Chisel edge angle.
4.Helix or rake angle.
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