Printing with polycarbonate.
I have been having some luck with polycarbonate filament. I will share my findings and hope to also receive some helpful suggestions from the community.
First of all, why polycarbonate? Well, it’s one of the toughest polymers - it has the highest impact strength of all extrudable polymers, and a tensile strength equaling nylon.
- it has the highest glass transition temperature and the highest heat deflection temperature of all extrudable polymers.
The latter property is the reason I need to print with polycarbonate.
However, the challenge with 3D printing it is also related to its great properties: the hotend needs to be at 270C - you may be able to print at 250C, but the inter-layer adhesion is very poor and it defeats the purpose of choosing polycarbonate. Then there is the fact that polycarbonate goes through considerable volume change during phase transition. This will cause warping similar to ABS printing, except ABS will “stay put” with sufficient adhesion to the printing bed. Polycarbonate is far less docile than ABS: good adhesion is achieved on BuildTAK, but during warping, polycarbonate will rip BuildTAK right off the glass on which it is glued!
Somewhat good adhesion can be achieved with clean glass with a thin layer of dry hairspray. But I could not find any way to avoid warping and partial detachment at corners and other such nucleation sites.
At least with BuildTAK you can print pieces with small footprint (below about 2 cm2). You can print, according to my experience, considerable volume, and even objects with much larger cross section, using this small footprint without detachment.
Before you ask: the bed must be heated to 100C. 120C is better for adhesion, but you are more likely to have the BuildTAK ripped off the glass substrate by the polycarbonate piece, at this high temperature.