The Difficulties of 3D Printing Polycarbonate
When we first started 3D printing at Access 3D Services we purchased machines that we were sure could print in Polycarbonate so that we could set ourselves apart from the average Joe with a 3D printer in his garage. However, there are a number of obstacles to overcome in order to print in Polycarbonate, and these obstacles must be taken into consideration before deciding whether or not Polycarbonate is the right thermoplastic for your application.
Unlike PLA or ABS which are more traditional 3D printed thermoplastics, in order to print in Polycarbonate you will need a hotend which can reach at least 280°C. Hotends which are able to reach temperatures capable of printing Polycarbonate will be all-metal and will not contain the PTFE tubing that lower-temperature hotends use to feed the filament into the nozzle. While Polycarbonate can be printed at temperatures as low as 250°C when the speed is kept to 20mm/sec or under, parts printed at such low temperatures tend to suffer from interlayer adhesion issues.
The next obstacle to overcome when 3D printing in Polycarbonate is bed adhesion. While PLA can be 3D printed on bare glass or on blue painter’s tape, Polycarbonate requires special treatment of the bed if printing on glass. At Access 3D Services we’ve found the best solution for Polycarbonate bed adhesion is a nice thick layer of ABS slurry. ABS slurry is created by dissolving ABS plastic in acetone. The slurry is applied to the glass plate with a foam brush then the plate is heated to 130°C. Polycarbonate also adheres very well to Buildtak™ surface pads. The high 130 degree temperature helps to combat warping, which is the final and most difficult obstacle to overcome when 3D printing in Polycarbonate.
One of the major benefits PLA has over ABS is that despite its brittleness it suffers almost zero shrinkage as it cools. ABS on the other hand shrinks significantly during cooling which can lead to warping of the lower layers and can seriously affect the dimensional accuracy of the 3D print. Polycarbonate is even more prone to warping than ABS as the highly heated plastic cools, which can cause problems with both bed adhesion and dimensional accuracy of the resulting part. Access 3D Services uses adhesive and heat to combat the effects of warping on 3D printed Polycarbonate by treating the glass bed surface with ABS slurry before heating the glass to 130°C. The extra heat helps to minimize the speed at which the printed part shrinks due to cooling, and the ABS slurry helps to ensure the part remains bonded to the bed and does not warp upwards off the heated surface. It’s also important to remember that the greater the mass of the printed object, the more shrinking it will suffer and as a result the more warping it will go through, so we always try to print Polycarbonate models with as little infill as possible in order to reduce the amount of warping.
Despite these obstacles Access 3D Services has been very successful in printing difficult-to-produce models in Polycarbonate. It’s important to keep in mind these important considerations when 3D printing an object in Polycarbonate. Without an all-metal hotend printing in Polycarbonate would not be possible, and without a heated bed the printed material will not adhere to the build surface due to the significant amount of warping Polycarbonate experiences as it cools. This warping must be combatted both in order to ensure bed adhesion as well as a dimensionally accurate part.
Article by Joe Eckert, Operations Director, Access 3D Services
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