Question

Calculate the MRR in a drilling process that is done with a 2 1 4 - inches radius drill bit, in one piece whose drilling depth is H = 5 3 8 inches and it takes 1/2 hr. Keep in mind that the perforation is not through the workpiece and that the conical tip of the hole has a height of ½ inch.

Answer 1

Data:

Hole depth, L_h = 5 3/8 = 5.375 in , Drill dia / hole dia, D = 2.25in,                                                

Cutting time = 0.5 hr = 30 min    

Soln:

Length of cut, Lc = 5 3/8 + 1/2 = 5.875 in

Cycle time, Tc = Lc / (f * N)

i.e., (f*N) = Lc / Tc = 5.875 / 30 = 0.196 in /min

Now, The material removal rate is MRR = (?D² / 4) (f*N)

MRR =   (?*2.25² / 4) (0.196) =0.78 in³/min

MRR = 0.78 in³/min OR 0.013 in³/s