13-09-2012, 04:23 PM
Machinability of Metals
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Machinability
Machinability of metal refers to the ease with which it can be worked with a machine tool.
It can be affected by metal properties such as Hardness, Tensile Strength,Microstructure.
Machine variables such as Cutting speed ,Feed, Depth of Cut.
Good Machinability Implies
Higher Cutting Speed.
Lower Power Consumption.
Chips Broken Easily.
Tool Life Increase.
Good Surface Finish.
Forces acting against Tool relatively Low.
Improving Machinability
Chemical Composition.
Microstructure.
Treatment Given to Metal.
Less Hardness, Less Ductility and less Tensile Strength.
Machinability Index
It defines as
Cutting speed of metal investigated for 20 min tool life *100
Cutting speed of a standard steel for 20 min tool life
A standard steel is free cutting steel which is machined relatively easily.
It has Machinability Index arbitrarily 100%.
Effects of Temperature and Friction
Heat created
Plastic deformation occurring in metal during process of forming chip
Friction created by chips sliding along cutting-tool face
Cutting temperature varies with each metal and increases with cutting speed and rate of metal removal