What is the term for the angle between the front of the cutting tool and a line that is perpendicular to the workpiece surface?

The term for the angle between the front of the cutting tool and a line that is perpendicular to the workpiece surface is known as the rake angle. This angle plays a critical role in the cutting process, affecting how the tool engages with the material being cut. A positive rake angle, for instance, reduces cutting force and improves chip formation, enabling smoother cuts and prolonging the tool's life.

Understanding this angle is essential for improving cutting efficiency, producing better surface finishes, and optimizing the overall machining operation. The rake angle directly influences the cutting dynamics, so familiarity with this term and how it functions in metal cutting is crucial for anyone involved in machining practices.

While relief angle, cutting angle, and tool angle are terms relevant to machining, they refer to different aspects. Relief angle pertains to the angle that provides clearance for the cutting edge against the workpiece, the cutting angle is not a standard term in machining, and tool angle can be somewhat ambiguous as it could refer to various tool orientations. Hence, the rake angle is the most appropriate term to describe the relationship outlined in the question.