Need suggestion for high temp material.

[Dennis Muhlestein]

Hello all,

I'm looking for a material that can withstand a higher temperature after it's been printed.  

Specs:  I need to print a part that can be exposed to a medical sterilization machine that reaches about 132C.  

Two questions:

1) I've tried Polycarbonate from Gizmodorks: http://gizmodorks.com/polycarbonate-3d-printer-filament/

  I have a couple problems with it that I haven't been able to get around yet.  The first is that I can't get it to stick for the life of me.  I'm printing on Kapton Tape w/ ABS juice and 120-130 hotbed for the best results but I've tried a number of other adhesives on the bed and a number of temperatures and it just doesn't like to stick.  Gizmodorks responded it'll bond very well to a pcb board even at lower temperatures but they didn't say where you could get something and didn't know the details of the board.  Anyway, at the higher hotbed temperatures I'm getting at least some adhesion with I also get cracking while it's printing and that isn't going to work.  So first question is if anyone has had better luck with this material and what perhaps I might try?

2) Perhaps there is another material I could try that would meet the original spec that I haven't looked into yet.

Any thoughts appreciated. TIA

[Ryan Carlyle]

High temp filaments warp a lot, period. There is no way around it. Warping is a function of how much the plastic cools after it fully solidifies. If your printer's chamber is 30C and the plastic is fully solid at 130C, that's 100C worth of thermal contraction that you're fighting. 

You MIGHT be able to use one of taulman's nylons. I believe 680 was specifically formulated for medical sterilization processes. (http://taulman3d.com/680-features.html) I don't think it's available yet though. 645 may hold up ok, depending on the stoutness of the part. That's probably what I would try, if you can't get PC to work.

The real problem with nylons for high-temp use is that their glass point is surprisingly low -- it's actually a bit viscoelastic over 70C or so. Nylon is only considered a high-temp filament when under VERY LOW loading. If stressed at elevated temps, nylon will continuously creep and deform. But the rate of creep is usually very low, so it may be perfectly suitable for temporary sterilization exposures. You would probably need to try it to find out. It may survive with acceptable deformation for a limited number of heat cycles, for example. 

If you need the part to actually be durable or mechanically loaded at all at 130C, polycarbonate may be the only practical option. Even then you'll need to be careful that it isn't stressed too much -- 130C is generally considered the upper limit for it to have acceptable strength.

You seriously need a hot chamber for PC to be workable at all. I run my R2x chamber around 55C when printing PC and it's still a warp-tastic pain in the ass. I have had seen good success with two different surfaces:

• Fresh UHU gluestick at 130C HBP temp
• ABS slurry at 95C HBP temp

ABS slurry sticks well, but the ABS layer itself gets soft over 95C and it cannot act as a stable interface between the Kapton and PC. So you have to dial back the HBP temp. That means more warping stress. 

If you're getting layer cracking, you're not printing with the nozzle hot enough and/or your filament is moist. PC MUST be oven-dried immediately before use, no matter how much desiccant is used during storage. (Nylon is similarly water-loving.) I recommend printing with the filament spool inside a drybox the entire time it's in use if you can manage that. 

[Andrew Aurigema]

You could drop back a bit in technology and make the part on your printer out of something easy to print and high resolution then cast a mold of it then cast the final part in high temp thermo-setting plastic.  The printer could be used to make the master part or to make lost wax disposable components that are lost in the process of reproduction.  I saw a few videos on casting with silicone rubber.  It was pretty involved but the final product was quite good.   

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[Dennis Muhlestein]

Thank you for the tips.  So I seem to have resolved the cracking by raising the temperature 5C to 275 instead of 270.  I've also enclosed the printer to perhaps raise the temperature a slightly in there but I don't think it's a great temperature gain, probably just a little more stable temperature.

Now if I can get the prints to stick better I think I might be in business.  I'll try the gluestick. Is that on top of Kapton Tape still?

[Ryan Carlyle]

I used gluestick on glass, but the gluestick often pulled free of the glass from the warping stress. You could try gluestick on Kapton. 

[Ryan Carlyle]

Enclosing the printer adds a lot of heat over an extended period of time. My R2x takes a couple hours to hit 50C. 

On Wednesday, September 3, 2014 12:44:48 PM UTC-5, Dennis Muhlestein wrote:

[Dennis Muhlestein]

So I actually got a good print with some gluestick on Kapton.  It started to pull slightly at the edges but stayed firm enough to print.   Still have some slight tweaking to do but I feel like I'm in the ballpark now at least.  The PC parts are very strong.  I have a reject part that came unstuck that I've tried to break and I can't damage it at all... at least with hands anyway.  Out to the shop for some hammers/saws next to see what it'll take :)

[Ryan Carlyle]

PC is roughly twice as strong as ABS. It's tough as hell. A but stronger and much stiffer than nylon even. Mechanically, I love it. But it's a PITA to print.