What Is Machinability Index and Characteristics of Machinability?
What is Machinability Index?
Machinability: The characteristics of a material which makes it easier to cut or machining with desired factors. Machinability index is the measure of hardness in a given material. It determines how easily a material can be machined.
A higher machinability index value indicates that harder and more time-consuming finishing work will be required in order to produce a surface finish acceptable for production operations. On the other hand, a lower machinability index value would indicate that less finishing work would be required compared to an equivalent surface finish produced by using an average tool steel grade.
The Machinability of material is a relative quantity, The different materials machinability is compared in terms of there machinability index. for this purpose, the machinability of free-cutting steel serves as a datum with refers to which all other machinability indexes are compared.
For finding the machinability of materials there is,
Machinability index= (Cutting speed of given metal for 20 mins tool life/Cutting speed of free-cutting steel for 20 minutes tool life)*100
The representative of machinability index for some materials are:
Material: Machinability index:
Stainless steel 25%
Low carbon Steel 55%-65%
Copper 70%
Red brass 180%
Aluminum alloys 300% – 1500%
Machinability characteristics of a material depends on:
- Physical property.
- Chemical properties.
- Mechanical properties.
- Cutting conditions.
- Microstructure.
