A chisel is a tool with a characteristically shaped cutting edge of a blade at its end for curving or cutting a hard material such as wood, stone, or metal. The handle and blade of some types of chisels are made up of metal with a sharp edge.
 It is made of high-carbon steel and has circular, hexagonal, or octagonal pieces. It has no proper size. According to need, shapes are used. Its head is the stand of 70° in conical shape by the forging rule and the bottom part made such a pyramid. The cutting part of the chisels is too hard and tempered by heat treatment. Its length range is 150 mm to 200 mm.
Types of Chisels and Their Uses in Workshop for Metal Work
There are many types of chisels and uses in the workshop given below.
(i) Hot: Chisel ITI
It is used for cutting metal in a hot position and is generally used in smithy and forging shops. The cutting edge angle is 30°. After the cutting a job, its cutting part should be cooled so that, its cutting edge is not too hard.
(ii) ColdÂ
It is mostly used in general works and is available in different shapes. This is used for cutting the metal in a cold position. According to the requirements of job operation and shape, it has many kinds.
Types of Cold Chisels
Some types of cold chisels are given below.
(a) FlatÂ
It is mostly used in general works such as cutting rivets or nuts. It is 120-150 mm long and its cutting edge is slightly curved. So that, it avoids the corner iron cutting.
(b) Cross CutÂ
It is mainly used for cutting grooves and keyways and the available length is from 5 to 9 mm. It is used where a bigger is not possible for cutting. The cross-cut is fatter and its one head is made such as a circular half-round gmove. It is also known as a cape chisel.
(c) Diamond PointÂ
It is used for cutting the V-shape grooves, cleaning corners, and squaring small holes. It is made of a hike-shaped cutting edge.
(d) Half RoundÂ
Half-round chisel is used for cutting oil grooves in bearing and round corner slots. Its tapered parts have a half-round circular shape.
(e) Cow Mouth Chisel UsesÂ
Its cutting edge is shown as a cow mouth. It is normally used for sheet round cutting, making round holes, and removing waste. It is mostly used to cut the diameter of any workpiece by its curved cutting edge. Sometimes, it is also used to remove the rivet head or cut of rubber washer, etc.
(f) HollowÂ
This is similar to a cow mouth chisel and its cutting parts have a conical shape and its cutting edge has a circular shape. This is used for digging a circular hole. A slit is made on the upper point of the cutting edge so that scrap material exists. This is used for cutting soft metal, leather, and rubber sheets.
(g) OffsetÂ
Its cutting edge consists of one side that is offset after forging. These chisels are of two types Le flat offset chisel and side offset chisel Flat offset chisel has its cutting edge completely wide and side cutting edge has cutting parts in its side. This is used for chipping
(h) WebÂ
A web chisel is used for separating metals after chain drilling. It is also called a punching chisel.
Chisel Cutting Angle
The angle that stands between the edge and the cutting lip as viewed from the end of the drill, is called the chisel cutting angle. Normally, the chisel edge angle is 60°.Â
According to ISI, cutting angles areÂ
| SL No | Metals | Flat | Cross-cut | Diamond Cut | Half Round |
| 01 | Iron | 70° | 70° | 60° | 45° |
| 02 | Cast Iron | 60° | 60° | 60° | 45° |
| 03 | Copper/Brass | 45° | 45° | 60° | 45° |
| 04 | Aluminium | 35° | 35° | 60° | 45° |
Chipping Process
This is the process of removing clogs or cutting metal during cutting by chisel is known as chipping. While you doing chipping, the job must be tight with vice and pay attention to the cutting point. During cutting. you must maintain an angle ie, of approximately 40° with the surface. Therefore, the rake angle is kept at 20°.
(i) Rake AngleÂ
It is the angle between the top face of the cutting point and normal to the work surface of its cutting edge.
(ii) Clearance AngleÂ
It is the angle between the bottom face of the print and tangent to the work surface originating at the cutting edge.
If the clearance angle is too low or zero, the rake angle is increased. The cutting edge cannot penetrate the work and will slip.
Process of ChippingÂ
During the chipping, you must obey the following rules.
(i) Always keep the in the left hand and the hammer in the right hand.Â
(ii) Job should be properly tight in vice and a soft steel plate should be placed below the job.Â
(iii) Always pay attention to the cutting point.Â
(iv) During the cutting, you must maintain an angle of 40° with the surface of the metal.Â
(v) While continuously using, we must be ground. The cutting edge hence it should be properly and effectively.
(vi) Dip in the water, often to keep up to temper.
Precautions While Using Chisels
(i) Always use safety goggles.
(ii) Use a chipping guard while you do chipping.Â
(iii) Hammerhead should be free from grease and oil.
(iv) The cutting edge of the should be ground according to the hardness of the job.
(v) Hold the job in vice securely.
(vi) The handle of the hammer should not be loose.
(vii) Below 100 mm in length, should not be used.
(viii) The cutting edge must be convex so that its age is increased and helps in cutting.