I also sand my parts and cover them with a protective epoxy (UV blocker).
For failure I’ve tested sheer and compression failures including in parts that where physically compromised e.g. by drilling screw holes or pressing in threaded inserts.
Unlike say ABS the failure was never across the layer lines and there was no layer separation or tearing if and when the parts broke they broke fairly cleanly.
Now this is for my specific application and use cases there could be stresses that could result in layer separation.
However I didn’t observed a significantly diminished z strength even when holes were drilled across the layer plain rather than just through it.
If you want to replace metal in general sintering or a lithographic process is likely going to be your best bet but FDM can work for many applications and you can always solve your material weaknesses in your design by for example altering the layer alignment across your design to ensure that the maximum strength is always where it’s need the most.
I beams are also much stronger in a specific direction but it’s not seen as a weakness but rather strength.
My experience with Ultem PEI was pretty solid I did do post processing mainly annealing: https://www.thomasnet.com/knowledge/annealing-of-ultem-pei-/
In a toaster over I hacked for temp control.
I also sand my parts and cover them with a protective epoxy (UV blocker).
For failure I’ve tested sheer and compression failures including in parts that where physically compromised e.g. by drilling screw holes or pressing in threaded inserts.
Unlike say ABS the failure was never across the layer lines and there was no layer separation or tearing if and when the parts broke they broke fairly cleanly.
Now this is for my specific application and use cases there could be stresses that could result in layer separation.
However I didn’t observed a significantly diminished z strength even when holes were drilled across the layer plain rather than just through it.
If you want to replace metal in general sintering or a lithographic process is likely going to be your best bet but FDM can work for many applications and you can always solve your material weaknesses in your design by for example altering the layer alignment across your design to ensure that the maximum strength is always where it’s need the most.
I beams are also much stronger in a specific direction but it’s not seen as a weakness but rather strength.