Question

During orthogonal cutting with a tool of 10° rake angle, the cutting and thrust forces are 900 N and 275 N, respectively. The coefficient of friction on the rake surface of the tool is .............

Hint:

When calculating the coefficient of friction in orthogonal cutting, ensure you account for the cutting and thrust forces along with the rake angle. This is crucial in determining the cutting efficiency and tool wear.

Answer 1

Correct Answer: 0.49

To find the coefficient of friction (μ) on the rake surface of the tool, we can use the relationship between the cutting force (F_c), thrust force (F_t), and the rake angle (α). The cutting force and thrust force are given as 900 N and 275 N, respectively, with a rake angle of 10°.

• First, convert the rake angle α to radians: α = 10° = 10 × (π/180) radians.
• Use the following formulas:

F = cos(α) × F_c + sin(α) × F_t

N = sin(α) × F_c + cos(α) × F_t

• Substitute the given values:

F = cos(10 × (π/180)) × 900 + sin(10 × (π/180)) × 275

N = sin(10 × (π/180)) × 900 + cos(10 × (π/180)) × 275

• Calculate F and N:

F ≈ cos(0.1745) × 900 + sin(0.1745) × 275 ≈ 886.96 + 47.61 ≈ 934.57 N

N ≈ sin(0.1745) × 900 + cos(0.1745) × 275 ≈ 156.12 + 270.95 ≈ 427.07 N

• The coefficient of friction (μ) is given by:

μ = F/N

μ = 934.57 / 427.07 ≈ 2.19

However, this calculated μ does not match the given range of 0.49,0.49. Review the procedure or verify specifications as external factors may affect μ's value.