Shaper machining time calculation

Given: plate length 300 mm, width 160 mm; cutting speed v = 12 m/min = 12,000 mm/min; cutting : return time = 3 : 2; feed 1.5 mm per stroke.

Stroke length

$$L = 300 + 15 + 15 = 330\ \text{mm}$$

Double strokes per minute

Let k be the ratio of return time to cutting time: $k = 2/3$.

Time for the cutting stroke = $L/v = 330/12000 = 0.0275$ min.

Time for one double stroke:

$$t = 0.0275\,(1 + k) = 0.0275\times 1.6667 = 0.04583\ \text{min}$$ $$n = \frac{1}{t} = \frac{v}{L(1+k)} = \frac{12000}{330\times 1.6667} = 21.8\ \text{strokes/min}$$

Number of strokes needed

Width to be covered = 160 + 10 = 170 mm.

$$\text{strokes} = \frac{170}{1.5} = 113.3 \approx 114$$

Machining time

$$T = \frac{114}{21.8} = 5.23\ \text{min}$$

Answer: n = 21.8 double strokes per minute; machining time = 5.23 min.