What is the term for the point at which a cutting tool can no longer be effectively used for its intended purpose?

The term that accurately describes the point at which a cutting tool can no longer be effectively used for its intended purpose is "Tool Failure." Tool failure refers to the complete loss of a tool's functionality, which can occur due to various factors such as excessive wear, chipping, or breaking of the cutting edge. This situation renders the tool ineffective for carrying out its intended operations, which typically leads to the need for replacement or significant reconditioning.

In contrast, "Tool Wear" refers to the gradual degradation of a tool’s cutting edge over time due to continual use, often impacting performance but not necessarily leading to immediate failure. "Tool Damage" implies a specific instance of harm resulting from external factors, such as a sudden impact or improper handling, which may affect a tool's efficiency but doesn't encompass the broader concept of complete loss of function. "Tool Limit," while it might suggest a threshold of cutting capability, isn't a widely accepted term in the context of cutting tool effectiveness, making "Tool Failure" the most accurate descriptor for this situation.