Calculate Drilling Speed and Machining Time
Calculate the drilling speed if a 50 mm dia hole of 60 mm depth is to be drilled in a M.S. component. The feed rate is 0.2652 and MRR is 200 cm3/min. Also calculate the machining time.
Solution
Given MRR = 200 cm^{3}/min
= 200000 mm^{3}/min
D = 50 mm
l = 60 mm
f = 0.2652 mm/rev
MRR = π D^{2} f N/ 4 mm^{3} / min
N = 200000 × 4/ (π× (50)^{2} × 0.2652)
= 384 rpm
V = π DN/1000
= (π × 50 × 384)/1000 = 60.3 m/min
Breakthrough distance, A = D/3.3286 = 50/ 3.3286 = 15 mm
Total length of drill travel, L = l + A + 2
= 60 + 15 + 2 = 77 mm
Time for drilling hole =
L / f N = 77/ (0.2652 × 384)
= 0.7561 min