Hello friends, Today we will Discuss about the Cutting tool failure in machining.
Types of Cutting tool failure:-
A] Mechanical Breakage:-
Mechanical breakage occurs due to excessive forces & shocks, which directly damage cutting edges of tool.
B] Plastic deformation:-
Plastic deformation occurs due to high stresses & higher temperature.
Hence the tool material looses its hardness & plastic deformation occurs.
C] Gradual wear:-
Wear failure occurs due to wearing of flank & rake surface of too.
i] Mechanical wear:-
The mechanical wear has two types.
The mechanical wear which occurs due to change in thermal conditions are known as thermally sensitive wear. E.g. Adhesion, fracturing.
And the mechanical failure which is not depend on change in thermal conditions are known as thermally insensitive wear E.g. Abrasive, Chipping.
ii] Thermo-Chemical wear:-
It occurs when two material got mutual affinity or mutual solubility. The constituent material of tool starts diffusing from tool to chips of work-piece.
If the diffusion is in bulk, then the diffusion is macro diffusion. If the diffusion is done atom by atom then it is then it known as micro diffusion. The rate of diffusion wear increases with increase in temperature.
D] Chemical wear:-
It occurs when tool material is not chemically inert. If the tool material has chemical affinity with tool material or working environmental conditions then this type of wear occurs. It can be eliminate by choosing proper tool material, or cutting fluid.
E] Electro-chemical wear:-
When at the tool chip interface the heat is generated, this causes generation of electric current by thermocouple effect.
How to identify cutting tool failure:-
- Breakage in tool tip.
- Fracture at cutting edges.
- Rise in vibration & cutting forces.
- Wear exceeds over limits.
- High power consumption.
- Higher noise & vibration.
- Poor surface finish.
- Abnormal chip formation.
When you can say the cutting tool is to be failed?
Due to following causes, we can say that cutting tool is to be failed:-
1) High power consumption.
2) Higher noise & vibration.
3) Poor surface finish.
4) Rise in vibration & cutting forces.
5) Breakage in tool tip.
6) Abnormal chip formation.