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GATE 2023 ME – Question 45

Computer Aided Manufacturing and Automation · NC/CNC machines and CNC programming · 2 marks · Multiple choice

A CNC machine has one of its linear positioning axes as shown in the figure, consisting of a motor rotating a lead screw, which in turn moves a nut horizontally on which a table is mounted. The motor moves in discrete rotational steps of 50 steps per revolution. The pitch of the screw is 5 mm and the total horizontal traverse length of the table is 100 mm. What is the total number of controllable locations at which the table can be positioned on this axis?

a motor driving a lead screw, a nut on the screw and a table on the nut.
  1. 5000
  2. 2
  3. 1000
  4. 200

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Correct answer: (C) 1000

Explanation

One revolution moves the table by the pitch of 5 mm and takes 50 steps, so each step moves it by $\frac{5}{50} = 0.1$ mm (the resolution). Over the 100 mm of traverse the table can be placed at steps of 0.1 mm, that is $\frac{100}{0.1} = 1000$ positions.