GATE 2023 ME – Question 55

Additive Manufacturing · Additive manufacturing processes · 2 marks · Numerical answer

A solid part (see figure) of polymer material is to be fabricated by additive manufacturing (AM) in square-shaped layers starting from the bottom of the part working upwards. The nozzle diameter of the AM machine is $a/10$ mm and the nozzle follows a linear serpentine path parallel to the sides of the square layers with a feed rate of $a/5$ mm/min.
Ignore any tool path motions other than those involved in adding material, and any other delays between layers or the serpentine scan lines.

The time taken to fabricate this part is ___________ minutes.
(Answer in integer)

a stepped solid made of three blocks stacked on each other. The bottom block is $3a \times 3a$ and $1.5a$ high, the middle block is $2a \times 2a$ and $a$ high, and the top block is $a \times a$ and $0.5a$ high. All dimensions are in mm.

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Correct answer: 9000

Explanation

The deposited bead is taken to have a cross-section of $d \times d$ with $d = \frac{a}{10}$ (road width and layer height both equal to the nozzle diameter). The volume deposited per minute is then $d^2 \times$ feed rate $= \left(\frac{a}{10}\right)^2 \times \frac{a}{5} = \frac{a^3}{500}$ mm$^3$/min. The volume of the part is $(3a)^2(1.5a) + (2a)^2(a) + a^2(0.5a) = 13.5a^3 + 4a^3 + 0.5a^3 = 18a^3$. The time is $\frac{18a^3}{a^3/500} = 9000$ min.