# Machinability Index

Written by Jerry Ratzlaff on . Posted in Manufacturing Engineering

Machinability index, abbreviated as Mi, a dimensionless number, is used to compare the machinability of different materials in the various cutting process.

## Machinability Index Formula

 $$\large{ Mi = \frac{ V_m }{ V_s } \; 100 }$$

### Where:

$$\large{ Mi }$$ = machinability index

$$\large{ V_s }$$ = cutting speed of standard steel for 20 minutes tool life

$$\large{ V_m }$$ = cutting speed of material investigated for 20 minutes tool life