There are other tool wear mechanisms which may be important in special circumstances. For example, in the sawing of green wood with carbide tools, chemical action may degrade the tool binder exposing the carbide skeleton to mechanical action and so wear.
Flank and rake face wear regions along with a rough estimate of the dependence of wear rate on cutting conditions is shown in this exercise.
In mechanical processes almost all energy is dissipated as heat with only a small part going to material structural changes. The implication for tool wear is that the heat generated causes a temperature rise that decreases tool material strength. So, wear rate is expected to increase with cutting conditions which produce higher temperatures in the cutting zone.
The power input to the chip formation process, P, is primarily due to the cutting force and cutting speed.
P = Fc VThe implication is that temperature in the chip formation zone depends critically on cutting speed. If V is held constant and feed rate and/or depth of cut is increased, cutting force will increase. The increase in machining forces with feed rate and depth of cut also increases power dissipated and so increasing temperature and increasing wear rate.
The process parameters of cutting speed, feed rate and depth of cut can be set in operations and are used in machining process models. The dependent variable, which is critically dependent on chip formation zone temperature, is tool life, T.
A very general tool life model is
V T n Fm dp = K'
The following exercise is aimed at adding meaning to this equation by providing a graphical representation of it.