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Railways NTPC (Technical Ability) Metal Forming, Casting and Cutting Question Bank Metal Cutting

  • question_answer
    Given that cutting speed = 9 m/min, the return time to cutting time ratio is = 1 : 2 to the feed rate = 0.3 mm/stroke, the clearance at each of cut = 25 mm and that the plate is fixed 700 mm side along the direction of tool travel, the time required for finishing one flat surface of a plate of size \[700\times 300\,\,mm\] in a shaper, will be:

    A) 10 min             

    B) 12.5 min

    C) 15 min             

    D) 20 min

    Correct Answer: B

    Solution :

    Number of strokes, \[n=\frac{Length\,\,of\,\,stroke}{Feed\,\,rate}\] \[=\frac{30}{0.3}=100\] Length of cut, \[L=700+2\times 25=750\,\,mm\] Cutting time \[=\frac{L\times n\times 1.5}{{{v}_{c}}}\] \[=\frac{0.75\times 100\times 1.5}{9}\]  \[=12.5\text{ }min\]


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