Polycarbonate

PEI is the best build surface for Polycarbonate. Standard build surfaces like blue tape and glue stick have adhesives that break down at the high temperatures required to print Polycarbonate. Build-tak can also be used but tends to permanently adhere to Polycarbonate at temperatures higher than 80°C, and can sometimes warp aggressively enough at this temperature to pull the Build-tak off the plate. PEI sheets consistently hold on to Polycarbonate at 110°C, without permanently adhering to the part. Once the bed cools down, the part usually self-releases, or can be easily removed with a spatula.

Due to the extreme printing temperatures and low cooling fan speeds required to print Polycarbonate, there is a high possibility of stringing and oozing with this material. To prevent this, try increasing the retraction distance and retraction speed. Simplify3D also includes a useful option called Coasting, which will automatically reduce the pressure in the nozzle right before the end of a segment to avoid oozing when moving to the next segment. This option can be enabled on the Extruders tab of your process settings. If your 3D printer can handle it, you can also try increasing the XY travel speed on the Speeds tab of your Simplify3D process settings. This allows the printer to make faster movements, which means less time for oozing. For other tips on how to prevent stringing and oozing, please refer to our Print Quality Guide which has an entire section dedicated to this issue.

Due to the high warping tendency of Polycarbonate, the first layer is extremely important when printing with this material. From our research, the material seems to stick the best with slow thick extrusions on the first layer. We recommend using a first layer height of 100-150%, a first layer width of 12-150%, and a first layer speed of 15-30%. All of these settings can be entered on the Layer tab of your Simplify3D process settings. Additionally, setting the first layer to print about 30° hotter than the rest of the part can greatly improve first layer adhesion.

High print temperatures mean that extruded filament will tend to droop if it is unsupported. Solid Infill Layers should be printed slowly, at around 50% speed, so that they have the best chance of successfully bridging the spaces between infill lines. At least 4 top layers should be used, which will ensure that top layers are as smooth as possible. Infill percentage should generally be kept higher than 25% density to ensure support for these top layers. If a part needs less infill, in order to be lighter or use less material, extra top layers can be added to increase the likelihood of a solid top-most layer.

Similar to the point above, bridging segments can also be affected by the high printing temperatures of Polycarbonate. As the plastic is extruded in thin air between either side of the bridge, it will have a tendency to droop while it cools. Simplify3D added many new bridging features in Version 4.0, so these can be used to customize exactly how the bridges are printed for the best results. We found that using a bridging speed multiplier of 40%, a bridging extrusion multiplier of 120%, and setting the bridging fan speed to come on at 25% offered a good starting point for most materials. You want to make sure the bridging fan speed stays at a low value, otherwise it has a tendency to cause warping and separation due to the rapid temperature change.