Broaching versus other Machining operations
Merits of Broaching Machining
1. Broaching is faster than other machining operations.
2. It enables a higher rate of production, more accuracy, and better finish than other operations.
3. Since each tooth of broach takes a small cut that too only once in one operation, it has longer life than other cutting tools.
4. Owing to the above reason, the tool cost per work piece is low.
5. A single tool (broach) performs both roughing and finishing operations.
6. Better surface finish is obtained because different teeth perform different operation.
7. Cutting fluid can be applied more easily and effectively than other operations.
8. Because of simplicity of machining cycle, it does not required highly skilled operator.
9. Interchangeable components can be produced at a much faster rate by broaching than any other operation.
10. A specific advantage in broaching is that the cutting force of the broach serves to clamp the work piece and hold it firmly in position.
Demerits of Broaching Machining
1. It is a single purpose tool and can produce only one type of surface.
2. The initial cost of the tool is very high compared to other tools.
3. It is unsuitable for small quantity and are of variable sizes.
4. All the jobs in broaching will need fixtures and this will add to the cost.
5. The broaching machine is costly of all machine tools its existence will not be justified unless production required is very high.
6. Tool sharpening is difficult and expensive, needs separate sharpening machine.
7. All types of surfaces can’t be machined through broaching.
8. Very light and delicate jobs cannot be broached easily, as they can’t with stand the cutting force.
9. Surfaces which lie in separate planes can’t be machined in single setting.
10. Blind holes cannot be easily produced through broaching.
A wide variety of shapes, internal, external, regular, irregular, including complex contours can be produced through broaching. Several shapes which are difficult to be machined on the other machine tools can be easily machined through broaching.
Broaching applications include the machining of bearing caps, bearing bodies, cylinder blocks, connecting rods, cylinder heads, crank cases, rotors, toothed sprockets for chain drives, gears, turbine blades, sleeves, bushings and air craft engine parts etc.
In broaching operation the machining time depends on effective length of broach i.e. the length of tooth system of the broach. It is given by the following relation.