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I see, then that is most likely the root cause of the issue, you need to mix in at least 50% fresh powder with SLS printers and 20% for MJF printers.

[Axl Hemmingway]

Hello, community! I have recently printed functional prototypes for snap-fit components using SLS with PA 12. The parts need to withstand repeated flexing without breaking. I noticed that the parts I’ve recently printed seem unusually brittle compared to previous batches and tend to crack or snap even under moderate stress. I haven’t made any design changes or material swaps between batches. Could this brittleness be caused by processing parameters or material degradation? Thnaks

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[DanML]

Considering that you have not made any changes to the material or the design, it is indeed likely that some processing parameters or material degradation is the culprit. Are you using recycled powder in these recent prints and if so how much new powder do you usually mix in?

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[Axl Hemmingway]

Yes I am using recycled powder, I don’t usually mix the new powder into the old powder, I usually take the old powder and just top it up with a small amount of new powder.

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[DanML]

I see, then that is most likely the root cause of the issue, you need to mix in at least 50% fresh powder with SLS printers and 20% for MJF printers.

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[Alex Bolt]

Another potential cause is moisture ingress. PA 12 (Nylon) readily absorbs moisture, especially if it’s in powder form, you need to store your powder in a completely dry environment.

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[Axl Hemmingway]

If I have left the powder exposed to a humid environment how can I go about drying the material out? Can I use an oven?If I have left the powder exposed to a humid environment how can I go about drying the material out? Can I use an oven?If I have left the powder exposed to a humid environment how can I go about drying the material out? Can I use an oven?

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[Alex Bolt]

The material can be dried provided it has not absorbed too much moisture. I would advise against putting it in an oven to dry, you will most likely cause the powder to melt and bond together. The safest is to dry small batches using a desiccant dryer.

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