I would love to see some documentation specifically describing methods to avoid introducing degraded powder into the Fuse system. I can think of a few topics where a significant gray area exists:
Hard-Caking: When running hot or printing the bed temperature calibration, hard-caking can occur. Should users separate hard-caked clumps and dispose of them instead of running them through the sift?
Melting: In the event of local or global melting (which I am unfortunately very familiar with), the layers a few inches below are typically affected. Should the powder near the melted layer be disposed of?
Surface Armor: A good amount of discussion has taken place regarding this topic. For example, in this post discussing depowdering using air: “Air blasting should not remove the semi-sintered powder on your part, so you should be getting back only good powder.” However, I think formal documentation would be helpful for users depowdering approach.
Is it true that semi sintered “Surface Armor” can pass through the sift sieve? My understanding was the surface armor particle size is larger and therefore should not pass through in large numbers or as a large percentage of the overall recovered powder. Not sure where I read this, perhaps in a research paper discussing refresh rates.
I think this is the paper I referred to earlier, its been a few years since I looked into this deeply. You can see the size difference or some grains between fresh and aged powder, and I imagine the semi sintered powder grain size is even larger due to individual particles fusing. I suppose it would not be too hard to reproduce this slide but include semi sintered powder comparison as well. That would be interesting to see.
Thanks for following up and tracking down that paper! I would also expect surface armor to have a larger grain size than the recycled sample shown. I can’t imagine it would be all that difficult for Formlabs to collect some grain size samples from their powder system to compare.
@jmasterson, thank you for asking about degraded powder and how to prevent it from entering the printer again. The good news is that anything that fits through the mesh screen is reusable powder. As powder gets used, it sticks to other grains of powder, making it too large to pass through the screen. You don’t want to use that powder.
Another thing to consider is the refresh rate you are using. I have a link to our support site for your convenience.
As always, if you’re having issues or would like more in-depth answers on this, you can always open a support case, and our agents will be happy to assist you.
