The secondary shear zone during metal machining lies between:

Concept:

Secondary Shear Zone (SSZ):

• It lies between the metal chip and cutting tool.
• In SSZ the energy supplied is converted into heat energy because of the presence of friction at the chip tool interface.
• About 30 to 35% of the energy supplied is converted into heat energy in the SSZ.
• Out of the heat generated the maximum amount of the heat is carried away by the chip, Only a small amount is transferred to the tool.
• This is because the thermal conductivity of the tool is less than the chip.

Primary Shear Zone (PSZ):

• It lies between the workpiece and metal chip.
• In the PSZ when shearing action os taking place, the atomic bond present between the atoms of the material is getting breaking.
• For breaking the atomic bond it needs to supply a certain amount of energy but during the breaking of the atomic bond, they release an equal amount of energy in the form of heat energy.
• Out of the heat generated the maximum (60 to 65%) amount of the heat is carried away by the chip.

Tertiary Shear Zone(TSZ):

• It lies between workpiece and cutting tool.
• In TSZ, the energy supplied is converted into heat energy is due to the presence of friction of the tool work interface.
• About 5 to 10% of the energy supplied is converted into heat energy in this zone.