What is the typical effect of increasing cutting speed on tool life, all else equal?

• A. It generally reduces tool life due to higher wear, all else equal.
• B. It generally increases tool life due to smoother cutting.
• C. It has no effect on tool life.
• D. It only affects surface finish, not tool life.

Answer: (A)

Raising cutting speed raises the temperature at the tool tip, which accelerates wear. Higher heat speeds up wear mechanisms like abrasion from chip particles, diffusion wear in the tool material, and oxidation, causing the cutting edge to dull and the tool to lose strength faster. Even if surface finish or chip flow improve, the increased wear rate generally means shorter tool life when speed is increased, assuming feed, depth of cut, and material stay the same. In practice, tool life often decreases as speed goes up, following a relationship where faster speeds shorten usable life. To manage this, speeds are chosen to balance productivity with wear, sometimes aided by coatings or tougher tool materials that resist heat.