Question

sls: moving parts
use the information below to answer the question.
sls printing can be used to make moving parts. there is no support structure other
than the powder that is in the powder bed.
moving part considerations
consider the thickness of the shafts and the mass to avoid over - sintering. in general,
if the print has a shaft that is less than 1 cm in diameter, there can be a clearance of
0.15 mm on each side. the mass will not build up too much heat, so it wont over-
sinter. if the shaft needs to be 1 cm, the clearance will be 0.25 mm on each side. it is
important to note that there will still be powder in between and it can over - sinter.
reduce surface area
to avoid over - sintering moving parts, a redesign that reduces the surface area and
contact is a good choice. there will be much less heat build - up, and the possibility of
over - sintering is reduced greatly. the clearance in the center will be 0.4 mm, and an
escape hole can be put in to allow the powder to get out.
why might an escape hole be put into an sls moving part?
to allow the powder to get out
to remove the support structure easier
to increase its internal heat
to equalize its pressure

Explanation:

From the text, under "Reduce surface area", it says an escape hole can be put in to allow the powder to get out. The other options don't match: there's no support structure other than powder (so B is wrong), escape holes are to avoid over - sintering (not increase heat, so C is wrong), and pressure equalization isn't mentioned (so D is wrong).

Answer:

A. to allow the powder to get out