The loads that act on a cutting tool fit in four basic
categories: mechanical, thermal, chemical, and tribological.
The four categories of load do not operate independently but
rather interact and influence the sum of their effects. The
machine power involved, the rigidity of the machine and part
fixturing , and even the skill of the machine operator also
affect machining results. Interplay of the loads produces a
variety of results, all with the same end: the tool deteriorates
and wears out or fails.