The tool may fail due to

In manufacturing and production technology, tools used for cutting or shaping materials can fail in various ways. Let’s go through the options:

Option A: Cracking at the cutting edge due to thermal stresses → Correct. When a tool is used under high heat conditions, such as during high-speed cutting, thermal stresses can build up. This can lead to cracking at the cutting edge due to the sudden expansion and contraction of the material.

Option B: Chipping of the cutting edge → Correct. The cutting edge can chip due to the impact forces or the abrasive nature of the material being worked on. This is a common form of failure, especially in brittle materials.

Option C: Plastic deformation of the cutting edge → Correct. Under excessive force or high temperature, the material at the cutting edge can undergo plastic deformation, meaning it changes shape permanently. This results in a loss of the tool's sharpness and effectiveness.

Since all of the mentioned causes can lead to tool failure, the correct answer is Option D: All of these. Each of these factors contributes to the degradation of the tool's cutting edge over time.