We are currently experiencing some issues with a few jigs that we use within an environmental oven. During testing the oven is set at 50 degrees Celsius and the the jig is subjected to contact with water. The jig is under constant load from a spring and therefore due to the high moisture absorption of the Formlabs materials; they tend to warp and deform.
Currently I have tried the jigs in both clear and tough resin with little joy. Does anyone have any other material suggestions that may reduce the moisture absorption of the jigs and ultimately ensure they last a while longer in these conditions? Any help would be very much appreciated
It’s almost surely not because of moisture. As stated in the TDS the cured resin water absorption is very low, it should not have any meaningful impact.
However, temperature does make the parts more soft and it’s not surprising to me that they move under constant load. You might want to try High Temp resin which seems to be the only one with decent temperature resistance, apart from Rigid which is a bit better than the others (but still way worse than HT) but it’s not available for at least a couple of months so…
Yes we’re awaiting the rigid material development. The high test seemed to be the next best option as you say; the heat deflection temperature is much greater than the alternatives. In your experience are all the materials resistant to absorption?
The two new materials are made for exactly the conditions you have. Rigidity and low creep under constant loading.
I just got a cartridge of the new Rigid resin and so far I like it. I’m working on a few small mold cavities with the new material.
The High Temp resin is pretty brittle - that may or may not be a concern for you.
I don’t know your cost and time constraints (why you are using a printed jig, etc) but it might make sense to look at plating the materials with someone like RepliForm.
Also, it is worth noting that the published cured resin water absorption rates might not apply at higher temperatures. You could certainly try sealing your jigs with a primer and see if that helps performance.
That’s something I’ve tried overnight; firstly curing the parts after coating in an oil and secondly applying a layer of thermal resistant lacquer to them following curing to seal them up from the moisture. So far they seem to be holding up much better in the chamber.
It’s just a quick jig really, one thing i have done is machined a brass insert so the majority of the spring force is exerted on a solid face however it’s a difficult profile to machine.
You can also print your jig with some cavities for standard metal rod or plate. Slide it in after curing and you can prevent some deflection that way. Some designs that can work out well, but sometimes it’s not possible.