Machinability Index

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
\(\large{ Mi = \frac{ V_m }{ V_s } \; 100 }\)
Symbol	English	Metric
\(\large{ Mi }\) = machinability index	\(\large{dimensionless}\)
\(\large{ V_s }\) = cutting speed of standard steel for 20 minutes tool life (surface)	\(\large{\frac{ft}{min}}\)	\(\large{\frac{m}{min}}\)
\(\large{ V_m }\) = cutting speed of material investigated for 20 minutes tool life (surface)	\(\large{\frac{ft}{min}}\)	\(\large{\frac{m}{min}}\)