What angle is formed by the tooth face and a line perpendicular to the back of the blade?

The angle formed by the tooth face and a line that is perpendicular to the back of the blade is known as the tooth rake angle. This angle is significant because it influences how the cutting edges interact with the material being machined.

The tooth rake angle affects the cutting action: a positive rake angle can reduce the cutting force and improve chip flow, which leads to better surface finish and longer tool life. It also has implications on how the tool handles different materials, affecting both cutting efficiency and tool wear.

Understanding the rake angle is crucial for selecting the appropriate tool for specific cutting conditions and materials, as it directly impacts the efficiency and effectiveness of the machining process.