SECTION 4.0
HOW A BROACH CUTTING TOOL WEARS

There is no known tool material that can completely withstand contact and rubbing at high temperatures and pressures over a period of time without some changes from its original contour. It becomes necessary, therefore, to think of the effect of the controlling factors not only upon the cutting process, but upon the performance of the broach cutting tool, which itself affects the cutting process. For the sake of recognition and understanding of the fundamentals of metal cutting, the effects of changes in the controlling factors have been described without regard to their influence upon such criteria as tool wear and tool life.