Question
A slot of 25 mm x 25 mm Is lo be milled in a workpiece of 300 mm length using a side and face milling cutter of diameter 100 mm, width 25 mm and having 20 teeth. For a depth of cut 5 mm, feed per tooth 0.1 mm, cutting speed 35 m/min and approach and over travel distance of 5 mm each, the time required for milling the slot is_______ minutes (round off to one decimal place)
Answer :
Correct answer is : 8.1
Given, cutter speed = 35 m/min, length of the workpiece = 300 mm, Approach and over travel = 5 mm, Diameter of the cutter = 100 mm, ∴ radius of the tool = 50 mm
Therefore,
35 = π × 0.100 × N
N = 111.4084 rpm
Length of cut (L) = Workpiece length + Approach + Over travel + Radius of tool
L = 300 + 5 + 5 + 50 = 360 mm
Time required for milling (single pass)
t =
∴ t = 1.615 min per pass
Since depth of cut is 5 mm, therefore for 25 mm of cut, 5 passes are required.
Total machining time = time per pass × number of pass
t = 1.6157 × 5 = 8.078 min
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