Question

What is the effect of increasing the rake angle of a cutting tool?

• A. Increases cutting forces
• B. Reduces cutting forces and improves chip flow
• C. Increases tool wear
• D. Decreases tool life drastically

Hint:

A larger rake angle makes a tool sharper, which reduces cutting forces.
However, this sharpness must be balanced against the loss of mechanical strength at the tool tip.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question asks about the mechanical consequences of increasing the rake angle of a single-point cutting tool in machining.

Step 2: Key Formula or Approach: This is a fundamental concept in metal cutting and tool geometry. The rake angle is the angle between the tool face and a plane perpendicular to the workpiece surface. It controls the direction of chip flow and the sharpness of the cutting edge.

Step 3: Detailed Explanation:

• A larger positive rake angle makes the cutting edge sharper and reduces the tool's wedge angle.

• This sharpness reduces the plastic deformation of the metal ahead of the tool, lowering the shear strain during chip formation.

• Consequently, less energy is needed to shear the metal, which significantly reduces the cutting forces and power consumption.

• Additionally, a larger rake angle provides a smoother path for the chip to slide over the tool face, improving chip flow.

• However, if the rake angle is increased too much, it reduces the tool's cross-sectional area, weakening the cutting edge and reducing its ability to dissipate heat.

Step 4: Final Answer:
Increasing the rake angle reduces cutting forces and improves chip flow.