What are the common causes of tool wear?

Tool wear is a critical consideration in machining as it directly affects the quality of the workpiece, production efficiency, and tool life. The correct answer identifies major mechanisms by which tools experience deterioration during use.

Abrasion occurs when hard particles or materials in the workpiece or cutting fluid come into contact with the cutting tool, gradually wearing away its edges. Adhesion pertains to the welding of workpiece material to the tool tip at high temperatures, leading to material removal from the tool. Fatigue refers to the progressive and localised structural damage that occurs when tools undergo cyclic loading, which can lead to chipping or fracture. Thermal shock is the rapid heating and cooling that tools experience during operation, causing stress that may result in cracking or brittleness.

Understanding these mechanisms allows machinists to select the right tools and conditions for a given task, ultimately reducing the frequency of tool replacements and maintaining productivity. While other factors like cuts from handling, improper storage, and environmental exposure can contribute to general tool degradation over time, they do not specifically drive the wear mechanisms that occur directly during machining operations. Hence, the focus on abrasion, adhesion, fatigue, and thermal shock is vital to understanding the primary causes of tool wear.