PEI bonded to Mic6
Posted: Mon Nov 05, 2018 4:44 am
Anyone ever tried bonding a sheet of PEI to a an aluminum Mic6 plate to combine the benefits of both? When I say bonding, I don't mean the typical adhesive sheet holding the two together, which will always bubble and release over time and ruin the surface level. I'm talking about resin bonding with a high performance two part adhesive that will not allow local delamination the way adhesive sheets do. I've been doing this with good results lately and the difference between the thermal expansion coefficient of both materials has not been causing the plate to warp. You get the rapid thermal conductivity of the aluminum plus all the benefits of PEI: works on pretty much all filament types, tough as hell and doesn't scratch easily and does not require surface prep between prints.
We started doing a lot of TPU at work and the aluminum/hairspray wasn't cutting it for that. Our Mic6 plates get pretty gouged up from people not properly re-leveling or resetting the Z height after a change, whereas PEI is pretty tolerant of small amounts of nozzle dragging. You have to screw up pretty big to actually leave a mark, whereas the aluminum has zero tolerance for collisions. Hairspray buildup in the corners of our aluminum plates also happens due to half-assed cleaning between prints. The discipline required for Mic6/hairspray build plates just isn't there in our group of operators, so I went on a build plate search. I tried a solid 1/4" sheet of PEI just to see how that would work (it wan't my $100, so why not?). As you might guess, that stuff warps when heated up and the poor thermal conductivity makes a sheet that thick take forever to heat up. So if you've ever though of trying solid PEI, don't go there.
What has worked best so far is using an areospace grade adhesive called Hysol 9360 with glass beads to maintain the bond line, roughing up both the aluminum and PEI surfaces with 60 grit orbital sander, applying the adhesive to the aluminum and then sandwiching the PEI and aluminum together between two plates of 3/4" Mic6 in a press under 1 ton. I leave it in the press for 10 hours, then use an M2 to heat cure it at 70C for an hour. The press squeezes out all air and the glass beads create an even bondline without allowing every last bit of resin to be squeezed out. Now, the 9360 is very expensive at about $100 per tube and you have to have a gun that runs on comrpessed air to even shoot it. You can get about 4 or 5 plates out of one tube, so you would be looking at $25 just for the adhesive, $20 for the PEI and $50 for the Mic6. So it's a $100 build plate by the time you are done. We use the 9360 at work so I can get the leftovers for free, but someone else doing this might want to investigate lower cost adhesives. If you do use Mic6 and have some plates that you have gouged up pretty bad over time and can no longer sand the marks out, this is a good way to recover the plate back to something usable. It's a one-shot deal though, if you botch the bond line and get an uneven spread on the adhesive you have to throw the whole thing away and start over since you'll never get the PEI back off again. I've made 5 so far and only messed up the first one before I started pressing between the two 3/4" Mic6 plates to evenly distribute the pressing force without bending anything. I'll report back in 6 months after I see how they hold up over time.
We started doing a lot of TPU at work and the aluminum/hairspray wasn't cutting it for that. Our Mic6 plates get pretty gouged up from people not properly re-leveling or resetting the Z height after a change, whereas PEI is pretty tolerant of small amounts of nozzle dragging. You have to screw up pretty big to actually leave a mark, whereas the aluminum has zero tolerance for collisions. Hairspray buildup in the corners of our aluminum plates also happens due to half-assed cleaning between prints. The discipline required for Mic6/hairspray build plates just isn't there in our group of operators, so I went on a build plate search. I tried a solid 1/4" sheet of PEI just to see how that would work (it wan't my $100, so why not?). As you might guess, that stuff warps when heated up and the poor thermal conductivity makes a sheet that thick take forever to heat up. So if you've ever though of trying solid PEI, don't go there.
What has worked best so far is using an areospace grade adhesive called Hysol 9360 with glass beads to maintain the bond line, roughing up both the aluminum and PEI surfaces with 60 grit orbital sander, applying the adhesive to the aluminum and then sandwiching the PEI and aluminum together between two plates of 3/4" Mic6 in a press under 1 ton. I leave it in the press for 10 hours, then use an M2 to heat cure it at 70C for an hour. The press squeezes out all air and the glass beads create an even bondline without allowing every last bit of resin to be squeezed out. Now, the 9360 is very expensive at about $100 per tube and you have to have a gun that runs on comrpessed air to even shoot it. You can get about 4 or 5 plates out of one tube, so you would be looking at $25 just for the adhesive, $20 for the PEI and $50 for the Mic6. So it's a $100 build plate by the time you are done. We use the 9360 at work so I can get the leftovers for free, but someone else doing this might want to investigate lower cost adhesives. If you do use Mic6 and have some plates that you have gouged up pretty bad over time and can no longer sand the marks out, this is a good way to recover the plate back to something usable. It's a one-shot deal though, if you botch the bond line and get an uneven spread on the adhesive you have to throw the whole thing away and start over since you'll never get the PEI back off again. I've made 5 so far and only messed up the first one before I started pressing between the two 3/4" Mic6 plates to evenly distribute the pressing force without bending anything. I'll report back in 6 months after I see how they hold up over time.