Back rake angles on lathe cutting tools are fixed and do not vary with material.

Back rake angles on lathe cutting tools are fixed and do not vary with material.

• A. True
• B. False
• C. Not sure
• D. Not applicable

Answer: (B)

Back rake angles are not fixed; they are chosen to suit the material and cutting conditions. The back rake angle affects chip flow, cutting forces, and edge strength, so a positive rake helps with soft, ductile materials by allowing chips to flow smoothly and reducing friction, while a smaller or even negative rake is used for harder materials to preserve edge strength and prevent chipping. Because material type, cutting speed, depth of cut, feed, and cooling all influence the optimal rake, the angle is varied rather than kept the same. So the statement is not correct.

Back rake angles are not fixed; they are chosen to suit the material and cutting conditions. The back rake angle affects chip flow, cutting forces, and edge strength, so a positive rake helps with soft, ductile materials by allowing chips to flow smoothly and reducing friction, while a smaller or even negative rake is used for harder materials to preserve edge strength and prevent chipping. Because material type, cutting speed, depth of cut, feed, and cooling all influence the optimal rake, the angle is varied rather than kept the same. So the statement is not correct.