Answer: B (gradual failure)
Explanation:
Fracture failure: This type of failure results when cutting force becomes excessive, leading to brittle fracture.
Gradual wear Gradual Failure: In this type of failure, failure is slow but progressive. As an machines becomes old, its performance and efficiency wear out gradually.
Temperature failure: This type of failure results when cutting temperature is too high for the tool material leading to the wear and tear of the machine.
Fracture and temperature failures are both immediate failure, but Gradual failure is most preferred because it leads to the longest possible use of the tool because it fails gradually.
