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

  • question_answer
    The ratio between two consecutive spindle speeds for a six-speed drilling machine using drills of diameter 6.25 to 25 mm size and at cutting velocity of 18 m/min is:

    A) 1.02                             

    B) 1.32

    C) 1.06                             

    D) 1.82

    Correct Answer: B

    Solution :

    \[{{\phi }^{5}}=\frac{25}{6.25}=4\] \[\phi =1.32\]


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