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  1. #1

    Printed Model of Motor Cooling Fan Breaks Apart When Operating

    I had a model maker design an electric air compressor motor cooling fan due to the fact that I broke the original one and they are now obsolete and no longer available. The fan mounts on the end of the crankshaft that turns the air pump, which is on the end of output shaft of the electric motor. The motor is 3450 RPM. The guy who designed the model has made several modifications to make it stronger, but each one has broken into several parts after a few minutes of operation. I have noticed that if you hold the fan in front of a light, you can see several pinholes in the blades. I have tried increasing the infill to 100% and changed some of the strength settings to no avail. The fans still break apart after a few minutes of operation. Does anyone have any ideas of how to correct this problem or is a 3D printed fan just not going to hold up to the axial forces? I am printing this with PETG and have used both a 0.4 and a 0.6 nozzle.
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  2. #2
    Staff Engineer
    Join Date
    Jun 2014
    Posts
    886
    It's possible that a nylon version of this fan would hold up better, but nylon can be challenging to print if you are the printing resource. As you are using PETG, another option would be to salt-anneal your prints which involves printing to 100 percent infill and burying the print in a ground salt bed. I've purchased and tested a coffee grinder by placing salt in it and found it generates very fine powder, suitable for this operation. You'd have that additional expense but they aren't particularly expensive. If you decide to go that route, seek a true grinder, not a chopper type mechanism. It's also important to clean out all the salt after done with the session as it will corrode the internal components when exposed to the slightest ambient humidity. The link includes a YouTube video examining the strength improvement. If you're satisfied with the appearance using a 0.6 mm nozzle, that's going to be slightly stronger than the 0.4 mm version.

    If you pursue this option, please post your progress and results.

  3. #3
    Thanks for the info. I am having a printing service print this model in nylon for me and if that one does not hold up I will try the salt annealing process.

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