What defines a sharp edge in machining?

A sharp edge in machining is defined as an edge that has not been dulled by wear. This characteristic is crucial because a sharp edge allows for effective cutting and shaping of materials with precision and efficiency. When a cutting tool or blade maintains a sharp edge, it can penetrate the material being machined with minimal resistance and without generating excessive heat. This enhances tool performance and prolongs its lifespan, as a sharp edge reduces the likelihood of damaging the tool or the workpiece.

The other options do not accurately define a sharp edge. For instance, an edge that can be easily rounded suggests that it lacks the necessary sharpness for effective cutting. An edge that is thicker than usual does not correlate with sharpness; in fact, increased thickness may hinder its cutting capability. Finally, an edge that requires additional sharpening indicates that it is no longer sharp and may have decreased performance, making it unsuitable for precise machining tasks. Hence, the focus on wear and maintenance in defining a sharp edge makes option B the most accurate choice.