Advanced Guide to printing Polycarbonate Filament

Author: Matt Tyson/Wednesday, 22 August 2018/Categories: User Guides, Material Guides, PC

Advanced Guide to printing Polycarbonate Filament
Authors Note

Thankyou for taking the time to read our guide on 3D printing PC. This article has been written to provide both printing and troubleshooting tips along with tips for post-printing processes like painting and support removal. We have highlighted important topics with a star (*) so please don't feel intimidated as sections in this guide may not be relevant to everyone, - Matt Tyson, 3D Printing Solutions

This user guide was last updated - 1st April 2020

One of the best engineering plastics available for 3D Printing, PC was previously considered a difficult material to print. With the rise of new grades of PC; today polycarbonate is an accessible and popular 3D printing filament for both desktop and industrial users. Polycarbonate (PC) offers excellent heat resistance and tensile strength for real world applications. 

Note: When it comes to 3D printing Polycarbonate, set up and settings may vary depending on the grade of PC. Polymakers PolyLite™ PC and PolyMax™ PC filaments for example have been optimized to print at lower printing temperatures (250°C). Advice in this guide is tailored towards printing grades of PC specifically optimize for 3D printing.

Contents:

Introduction
  What is PC?
  Requirements *

Printer Setup
  Spooling
  Loading & Unloading Filament *
  Bed Surface *
  Bed Leveling & Nozzle Height *
  Pre-heating *
  Enclosure *
  Filament Storage

Printer Settings
  Nozzle Temperature *
  Bed Temperature *
  Heated Chamber *
  Cooling *
  Rafts / Brims
  Supports

Post Printing
  Removing a print after completion *
  Annealing *
  Removing Layer Lines
  Painting
  Joining

Trouble Shooting
  Poor surface quality
  Blocked Nozzle / Filament Jam
  Heat Creep
  Stringing / Oozing
  Warping
  Cracking
  Poor Layer Adhesion
  Smell during printing
  Difficult to remove prints
  Difficult to remove supports / raft

Filament Links
  Purchase or learn about PC Filaments


INTRODUCTION


What is Polycarbonate PC?

Polycarbonate (PC) is an amorphous plastic which is made up of carbonate groups in its chemical structure.

PC is a rigid material offering fantastic stiffness, strength and heat resistance. PC exhibits a moderate chemical resistance and excellent temperature resistance, with some grades softening between 145–150 °C (Glass Transition and Vicat temperature).

Not all Polycarbonate filaments are equal and the most popular and easiest to use Polycarbonate materials are those that have been optimized for 3D printing. Filament manufacturer Polymaker assisted with the rise of PC 3D printing by formulating the first optimized PC material for both desktop and industrial 3D printing, their filament PolyLite™ PC is less demanding and prints at 250°C instead of requiring a 300°C nozzle temperature and heated chamber.

PolyMax™ PC is a nano-reinforced  and optimized polycarbonate material exhibiting vastly superior impact resistance when compared with other grades of polycarbonate. PolyMax™ PC also offers a further improved printing experience, printing with less warping and with easier to remove support material.

Like other grades of polycarbonate, PolyMax™ PC offers moderate chemical resistance and excellent temperature resistance, softening at 113°C (Glass Transition and Vicat temperature).

Requirements *

An enclosed professional 3D printer is highly recommended to print PC. We recommend only printing with a quality PC filament.

Minimum Extruder Temperature - 250°C (±10°C)  is required (Correct temperature will vary on your printer)
Heated Bed - Required, 90° - 105°C.
Enclosure - Highly recommended for best results.
Heated Chamber - Beneficial
Part Cooling Fan - OFF
Feeding / Spooling - No specific requirements.
Other Notes - N/A

Most 3D printing slicers (software) have a pre-configured PC or ABS profile. The accuracy of this profile may vary depending on if you are using 1st or 3rd party filament, but we recommend duplicating your PC or ABS profile to start with and making necessary adjustments covered in this article.


Printer Setup


Feeding path and spooling

PC doesn't have any specific feeding path requirements.

As a general tip we recommend avoiding long and complicated feeding paths that can cause bends in the filament, this can introduce drag on the filament that may result in difficulties feeding and extruding.

If you typically have issues with moisture in your filament, you can read our tips and comments on filament storage to determine if a dry box will be beneficial.

Loading and Unloading Filament *

Changing from a PC material
If the printer is currently loaded with PC or a similar material, unload that material at 250-300°C and extrude your Pc filament at the same temperature. Stop extruding the PC filament after the previous colour is completely purged.

Changing from a higher temperature material:
If the printer is currently loaded with a higher temperature material, unload that material at its recommended printing temperature, and then load and extrude your PC filament at that same higher temperature. It is important to load the PC at this higher temperature so the previous material can be pushed out.  Stop extruding the PC filament after the previous material has been completely purged and cleaned out, lower the temperature to suit your PC filament and extrude the PC plastic for a few more seconds.

Changing from a lower temperature material:
If the printer is currently loaded with a different lower temperature material, unload that material at its recommended printing temperature, and then load and extrude your PC filament at 250-300°C. Stop extruding the PC filament after the previous material has been completely purged and cleaned out. 

Bed Surface *

Printing with the right bed surface is very important when printing PC. For PC we recommend first trying the surface your 3D printer was designed to use. If you have had success 3D printing PC before then PC should perform similarly.

Platform Material Recommended Surfaces
Glass Bed [1]

Recommended - Straight on glass bed with a thin layer of Magigoo PC or glue.

Overlay options - Buildtak or FlashForge style sheet [2] | PEI sheet.

Aluminium Bed

Most popular - Buildtak or FlashForge style sheet [2]

Other options - PEI sheet

Perforated Board

Most popular -Straight onto perforated board [3]

Other options - Buildtak or FlashForge style sheet [2]

Flex Plate (possibly magnetic)

Most popular - Buildtak or FlashForge style sheet [2]

Other options - PEI sheet

Notes:
[1] - If you are not using Magigoo (an adhesive which self-releases), we highly recommend removing your models immediately after printing when printing directly to glass. 
[2] - Pc can stick to printing surfaces and sheets very well, sometimes too well. If models are fusing to the sheets you can increase your nozzle gap or add a layer of Magigoo PC or glue to act as an interface.
[3] - This method is generally successful however will rely on compatibility between the PC and material of the perforated board. With a compatible combination the perforation on the board will grip the model during printing to help prevent lifting or warping. A raft is recommended for the best results.

Bed Leveling & Nozzle Height *

It is important when printing PC that your first layer adheres to the printing bed.

  • Your bed must be properly leveled.
  • Your nozzle height must be set correctly. (distance between the nozzle and bed)

Since PC will require a heated bed when printing, preheat the heated bed (90 - 100°C) before calibrating your nozzle height or leveling.

The ideal gap between the nozzle and bed is typically a distance of 0.1mm, this is the thickness of two pieces of paper. When changing between bed surfaces it is important to adjust the nozzle height again to compensate for the added thickness of the bed surface.

Pre-Heating *

For optimal results, it is recommended that you pre-heat the buildplate to 90°C at least 10 minutes before 3D printing PC. Preheating will help to ensure the bed is evenly heated and increase the ambient temperature to minimize risk of warping.

A longer pre-heating time (30 minutes - 2 hours) may be required in cases such as: printing in colder climates, owning a large format 3D printer or owning a printer with a lower wattage heated bed.

If your 3D printer is equipped with a heated chamber, we recommend preheating the heated chamber for 5 to 15 minutes before printing.

Enclosure *

Without the right printing environment, PC will print with too much residual stress which cause parts to warp or crack, compromising the mechanical strength of the part. 

An enclosure is highly recommended when 3D printing PC however users will find they can print some small geometries without an enclosure. Many enclosed printers have top lids / doors which can be opened or removed. When printing PC on these printers, we recommend closing all doors and lids to maintain a high environmental temperature.

Photo: The Tiertime UP300 (left), Raise3D PRO2 (center) and Ultimaker S5 with Air Manager Accessory (Right) are enclosed desktop 3D printers, a benefit when 3D printing polycarbonate filaments.

Filament Storage

When not in use PC should be stored away from sunlight and in a resealable bag with desiccant.

Like many other plastics, PC is a mildly hygroscopic material that will over time absorb moisture from its surrounding environment. This process typically occurs over a period of months however in high humidity environments (ie. evaporative air conditioning) this process can occur more rapidly.

Printing with a dry box is generally not a critical requirement to print PC (in most cases) however a dry box can be beneficial and ensure consistent printing quality and mechanical results throughout the spool.

Effects of Moisture:
When the filament passes through the hot end the moisture rapidly expands creating bubbles in between layers, poor layer adhesion, inconsistent extrusion due to material expansion and thus poor surface quality.

Preventing Moisture Absorption:
To eliminate all possibilities of moisture impacting your 3D prints, you must store and print your PC materials in their optimum environment (below 20% humidity) to prevent moisture absorption.

Some users will simply dry their filament before use however excessive drying will degrade the filament. We recommend storing all filaments in a resealable bag with desiccant when not in use and we recommend using a filament dry box like the PolyBox™ when printing. The PolyBox™ is a spool holder / dry box that stores filament in their optimal environment while printing.

Removing Moisture:
If your filament has absorbed moisture it can be dried in a convection oven. Visit our 'starters guide to moisture, drying and filament storage' for recommended drying times.


Printer Settings


Nozzle Temperature *

Polycarbonate is considered a high temperature material, with printing temperatures ranging from 250°C - 300°C depending on the brand.

The optimal printing temperature will vary on the printer you are using and type of PC, for PolyLite™ PC or PolyMax™ PC this is between 250°C - 270°C. To find the optimal nozzle temperature we recommend starting with a temperature right in the middle of the manufacturer’s suggested settings. If the manufacturer recommends 250°C - 270°C, printing at 260°C is a good starting point. Based on the quality of the print we suggest adjusting ± 5°C at a time.

Troubleshooting Nozzle Temperature
If the nozzle temperature is too hot, you may experience wisps / stringing on the surface of the print, difficult to remove and fused support material , sagging and poor surface quality on overhangs and a noticeable smell during printing.

If the nozzle temperature isn't hot enough, you may experience compromised mechanical properties due to the poor layer adhesion, under-extrusion (uneven / rough surface quality) and if the filament is not melting fast enough; nozzle blockages.  

Bed Temperature *

PC requires a heated bed set at 90°C -120°C depending on the brand. It is important your heated bed isn’t set above the materials glass transition temperature.

For example the glass transition temperature of PolyLite™ PC is 113˚C.

Heated Chamber *

A heated chamber is not required to successfully print parts in PC however will provide significant benefits when printing large and full-size parts. A controlled actively heated chamber will minimize internal stress (resulting in improved mechanical performance) and ensuring near-zero warping at all sizes.

On printers equipped with a heated chamber and water cooled extruder, we recommend setting the chamber between 60-70°C. If your extruder is not water cooled we recommend heating the chamber to 40-60°C to prevent heat creep.

Photo: Advanced Thermal System on the INTAMSYS FUNMAT HT maintains a high internal chamber temperature to print polycarbonate with near-zero warping. 

Cooling *

When printing PC it is recommended to print with the part cooling fan OFF to prevent curling and warping.

LOW fan settings may be applied to improve overhang quality, especially when printing with a heated chamber. The ideal fan setting may be anywhere between 5% - 50%.

Rafts / Brim

A brim is a thin layer of material surrounding the print that can be added help improve bed adhesion. The brim can be removed once the print has completed.

A raft is a foundation for the model to print on top of. A raft can be beneficial when printing PC materials and can improve adhesion especially when printing without a heated chamber or with some printing surfaces. The raft can be removed once the print has completed.

With some leveling systems manufacturers may specifically recommend a raft to compensate.

Supports

When printing PC, supports can either be printed in PC or with a second dedicated support material. Printing with a secondary material will require a printer capable of multi-material / dual extrusion printing.

PC Supports - With single extrusion 3D printers the model and supports are printed with the same material. When printing both the supports and model in PC, pliers and a small scalpel may be needed in some cases.

Breakaway Supports - PolySupport™ is a break away support material which offers good compatibility with PC and was originally designed to break way from PLA.

With PolySupport™ you can take advantage of the different softening temperatures to make PolySupport™ peel away with ease. Place the print with supports attached in an oven and heat to 70°C or simply keep the supports on when annealing to soften the PolySupport™ for removal.

Soluble Supports - PC can be printed with a secondary support material that has been engineered to dissolve in a solvent. Soluble support materials enable users to print complex geometry with superior surface finish on undersides. When printing PC with multi-material capabilities we recommend using PolyDissolve™ S2.

When using soluble supports we recommend having no gap (z distance) between the model and supports.

Support Troubleshooting - If supports are fusing to the model, try decreasing the printing temperature by -5°C adjustments or increase the distance between the model and supports.

If your supports are failing / collapsing during the print, try increasing support density and printing with a raft, this will improve adhesion for the supports.


Post 3D Printing


Removing a print after completion *

Once your 3D print has completed, it can be removed from the build plate. The best method to remove your PC 3D prints will depend on your build platform with some of these methods specific to removing PC prints. 

Rigid Build Platform
On rigid build platforms like glass or aluminium, a sharp paint scraper can be used to easily remove the model.

When printing on glass, in most cases the PC print must be removed from the glass platform when the temperature is high. Removing a print after the bed has cooled may cause the glass to break as the print can shrink more rapidly than the glass plate.

As a solution we recommend applying a thin layer of Magigoo PC before printing, with Magigoo the model can self release as the bed cools.

Some printers are designed so the platform can be removed from the bed while other printers the build platform may be fixed inside the printer. If the platform is fixed, we recommend supporting the platform with your second hand to prevent uneven pressure on the bed which could affect your bed leveling.

Flexible Build Platform
Some printers on the market print on flexible build plates. With these platforms users can flex the plate to remove prints.

Click here if you are having issues removing prints from the build platform.

Annealing *

What is Annealing?

Annealing is a process commonly used in metallurgy to heat the material and remove internal stress and toughen parts. A similar annealing process can be applied with some 3D printing materials and in the case of polycarbonate, will release internal stress maximizing mechanical performance.

Tips & benefits of Annealing Polycarbonate (PC)
A part which isn’t annealed will slowly release any internal stress in the form of micro-cracking, which can compromise up to 50% of the parts strength. Annealing polycarbonate releases the internal stress properly, maintaining the materials true strength and toughness.

To anneal polycarbonate, place the part in a preheated oven for one to two hours at 100˚C.

Polycarbonate will also 3D print with less stress and thus better strength when printing with an enclosure and or a heated chamber.

Removing Layer Lines

With any extrusion based 3D printing process, layer lines are inevitable. For applications requiring the best surface finish, these layer lines can be removed through post-processing. We recommend sanding to eliminate the layer lines from PC 3D prints however parts can also be post-processed with techniques like tumbling.

We recommend printing your parts with at least 3 perimeters/shells or a minimum wall thickness of 1.2mm if you plan on sanding. This wall thickness will ensure you don’t sand past the external shell and reach the infil. 

Wet or dry sanding with a foam block is the most common process to smooth 3D prints. The pressure can be evened through the foam block to create a smoother surface. For the best surface finish we recommend wet sanding. The water will assist to keep the sand paper clean and will dissipate heat from the sanding.

Start with coarse sandpaper and end with high grit sandpaper while always maintaining a circular motion. The ideal grit to choose will depend on what surface quality you require. If you are planning to paint the part, then 240grit sandpaper is sufficient and will also create a nice key for the paint to bond to the PC. If you do not plan on painting the surface, PC can be sanded to a very nice matte finish, this will require a higher grit of sandpaper up to 600.

Please wear a face mask when sanding to prevent breathing any dust or particles.

The high impact resistance of Polycarbonate also makes tumbling a suitable option for automatic post-processing. Vibrational tumbling removes layer lines from the printed part by vibrating grit particles which slowly fall and scratch the surface of the part. Just like sandpaper, there are many different grades of tumbling grit. Low grade grit can be used to make coarse surfaces while higher grade grit can make very smooth and fine surfaces. When choosing the correct stones, the grit shape, size and the geometry of the model is important to consider.

Vibrational tumbling is a slow process and easy to monitor the results.

Painting

Polycarbonate plastics can be easily painted with acrylic, hardened 2k paints and enamel based paints. We recommend removing layer lines before painting and using a plastic primer.  

Unsuitable combinations of solvents in the paint system can attack the material and, depending on the stress condition of the parts, may initiate stress cracking. It is therefore recommended to contact the paint manufacturers who can supply suitable paint systems especially for PC.

Joining

Parts printed in PC can be joined with a variety of techniques

Gluing parts printed in PC is simple, with SCIGRIP #16 Fast Set Solvent Acyrlic Cement, Super Glue or Two Part Epoxies. We recommend sanding contact surfaces with a coarse sandpaper to increase the surface area for the glue, this will result in a stronger join.


Trouble Shooting


Poor surface quality

PC typically prints with an attractive satin surface finish. Please consider these notes if the surface quality of your models is rough or textured 

Improving surface quality.

  • We first suggest checking that your spool of PC is dry. An easy way to test for moisture content in a spool of filament is to extrude the filament, if you hear a distinct popping sound your filament has likely absorbed moisture. As the filament is extruded, the moisture will expand and rupture in the filament creating a rough and inconsistent extrusion. Typically If you experience issues with moisture, printing with a dry box and applying preventative measures will be important to maintain the best printing results.
  • If your extruder temperature or flow rate is too low during printing, the PC filament won't extrude properly, leaving gaps within the model. Printing with the correct nozzle temperature will solve this issue.
  • Too much friction on the filament feeding path can result in under extrusion. To reduce resistance on the filament you can move the spool holder closer to the 3D printer and check the curve of the filament guide tube is not too tight.
  • If your extruder temperature is too high during printing, the filament can sag when printing steep unsupported overhangs. We recommend printing with the cooling fan set to a LOW setting to achieve the best underside surface quality. Printing with a lower nozzle temperature can also improve overhang surface quality.
  • If your nozzle is partially blocked the filament will have difficulty extruding. Click here for trouble shooting tips regarding blocked nozzles.
  • Slowing down your printing speeds can help to minimize vibration, ensure consistent extrusion and improve printing quality. 
  • Printing with the wrong retraction settings can negatively impact the quality of a 3D print. If the retraction distance is too high and the retraction speed is too slow, the nozzle won't be primed with enough material when the next layer starts, resulting in gaps. Temporarily turning off retraction settings is one way to see if retraction is causing gaps in the model. If the poor quality is related to retraction, printing with a lower retraction distance, faster retraction speed or turning off coasting may solve under extrusion when printing with retraction. If the retraction speed is too high, the feeding gear may grind the filament, causing a filament jam.
  • If there are gaps in the top surface of your 3D print this is commonly referred to as pitting. Pitting can be related to temperature or moisture however generally occurs when the infil is to low to support the top layers of the 3D print. This can be solved by increasing the number of top layers on your model to match the layer height you are printing. 6 top layers with a 0.2mm layer height will result in a 1.2mm top surface thickness, the same number of top layers at 0.1mm layer height will only result in a 0.6mm top surface thickness. Printing with 12 top layers with a 0.1mm layer height will achieve the 1.2mm top surface thickness.

Click here if you are having issues with wisps and stringing.

Blocked Nozzle / Filament Jam

When 3D Printing it is possible to encounter filament jams or nozzle blockages, these blockages can be caused due to a variety of reasons.

Causes and Steps to Prevent Nozzle Blockage and filament jams.
In all of these cases if the filament cannot pass through the extruder, the extruder gear will continue to try push the filament and will eventually 'chew out' the filament. If you hear a clicking or clunking sound coming from the extruder, this is a good sign that the filament is jammed or will be if ignored. 

  • If your extruder temperature is too low during printing, the PC filament will not flow and will have difficulty extruding. Printing with the correct nozzle temperature will solve this issue.
  • If the filament is softening in the hot end, the extruder will 'chew out' the filament, causing a nozzle jam. This issue is known as heat creep, click here to learn more about this issue.
  • If you are printing with a heated chamber, the chamber temperature may be too high and may be softening the filament near the extruder gear. Try printing with the heated chamber turned off to see if reliability improves, you may find that the chamber temperature should be lower for your 3D printer.
  • If there is too much friction on the filament, the extruder may have difficulties feeding the plastic. Try feeding the filament with a spool holder in different positions (above, beside, behind the printer).
  • Too much retraction or grip / tension from the extruder gear can cause filament to chew out and jam. Adjusting retraction behavior or the extruder gear tension can solve this issue.
  • If the nozzle height is set too close to the bed, the filament will have difficulty feeding through the nozzle eventually causing a filament jam. When printing at finer layer heights (0.1 and 0.05mm) the correct nozzle height is even more important. To prevent this issue it is important to print with the bed leveled and the correct nozzle height.
  • If the part is warping or lifting off the bed, the part will be pushing against the nozzle limiting extrusion and material flow, in this case it is important to prevent the part from warping.
  • If the printing speed is faster than the filament can reliably melt and extrude a jam may occur. Decreasing the printing speed may help prevent this issue in the future.
  • Nozzle Blockages can occur more commonly with finer nozzles. The majority of 3D Printers are equipped with 0.4mm nozzles, it is important when printing or experimenting with a smaller nozzle (0.2mm) to adjust printing speed and extrusion settings 
  • If the filament is of poor quality is oval shaped or manufactured with an inconsistent diameter, this can cause the filament to jam in the extruder. The industry standard for filament tolerance is ± 0.05 mm. If the filament is 1.75mm an acceptable diameter variance would be between 1.70 - 1.80mm. Premium and higher quality brands can offer ± 0.02 mm tolerance. If you have difficulties printing PC with only specific brands of filament this could signify issue with their quality control or simply printer compatibility.

Cleaning an PC Nozzle Blockage
If the nozzle is blocked with PC one of the most successful solutions is to increase the nozzle temperature and manually feed more PC through the extruder / hot end. As polycarbonate is a considerably tough material, with assistance and a high nozzle temperature you can generally purge and remove the clogged plastic.

Heat Creep

What is heat creep?

Jamming can occur when heat creeps up the extruder to the extruder gear and softens the filament too early. This can cause many problems including the filament chewing out instead of gripping and feeding through the hot end.

PC does not commonly suffer from heat creep related issues due to it's high softening temperature however heat creep jamming can be encountered when printing with a heated chamber set too high. 

Solutions to preventing heat creep.

The first step is to make sure your extruder fan or water cooling system is cooling the extruder as intended. If you are printing with a heated chamber and encounter heat creep related jamming we recommend first lowering the chamber temperature. It is important to note we recommend different chamber temperatures depending on how your extruder is cooled.

Printing on the lower end of the materials extrusion temperature can also help reduce heat creep in some cases.

Stringing / Oozing

PC based materials can flow more easily than other materials leaving behind wisps of plastic during travel movements. By controlling the travel and flow behavior in the slicing software we can minimize and prevent oozing and stringing.

Minimizing and preventing stringing.

  • Printing with a cooler nozzle temperature will in many cases help to reduce unwanted oozing as the plastic will flow and solidify at a different rate.
  • By increasing the retraction length or retraction speed in your slicer settings, the extruder will withdraw a short distance filament from the nozzle, helping to prevent oozing when the extruder travels between points.
  • If the spool has absorbed moisture, the moisture will affect the flow rate and viscosity of the material causing unwanted stringing and wisps.
  • Advanced slicer settings like coasting can be turned on to effectively reduce stringing.
  • When printing with a heated chamber, if the temperature is set too high you may notice more oozing and stringing. If the oozing is a result of the heated chamber you can experiment with lower chamber temperatures to control the flow behavior.

Warping

When printing higher temperature amorphous materials like PC, some users can have difficulty preventing warping, firstly lets look at why PC materials can warp.

Warping is caused by internal stress in the 3D printed part; there is one cause for internal stress when printing amorphous materials.

1. As the filament is extruded through the small diameter of the nozzle, the polymer chain of the filament is stretched and will want to return back to its ‘normal’ state, much like a stretched elastic band will go back to its position when it is released. If the PC is printed in a heated environment, the polymer chain will 'relax', releasing the internal stress and preventing the part from warping. If the material is printed without a heated environment the material will print with residual stress. As more plastic is deposited during large prints the residual stress will eventually overcome the bed or inter-layer adhesion and cause cracking or warping.

So how can we prevent warping and achieve near-zero warping when printing PC.

Preventing PC warping.

  • If parts are warping early into the print, this may be due to insufficient bed adhesion or an incorrect nozzle height. If the first layer of extruded plastic is not sticking to the bed, the internal stress during printing will be enough to quickly lift the part off the bed. It is important to ensure your nozzle height and bed is leveled correctly and that you are using the correct printing surfaces for PC.
  • Printing on a printer equipped with an actively heated chamber is one solution to printing PC with near-zero warping. A heated chamber is important to successfully print large full-size parts in PC (eg. 300 x 300 x 300mm).
  • Drafts, cool air from air conditioners and low environmental temperatures in winter can cause the PC to print with more internal stress. An enclosure with a closed front door can help to contain heat from the heated bed, raising the internal temperature required to minimize warping.
  • Not every heated bed is made equal, some designs heat from the center, reaching lower temperatures around the edges of the build platform. Preheating can help to even out the temperature across the print bed.
  • In an enclosed build volume of 150 x 150 x 150mm, heat from the build plate will raise the internal chamber more efficiently and faster than with a larger 250 x 250 x 250mm build volume. Preheating for a longer time may be required on larger printers to reach the required internal temperatures. 
  • Printing with a lower infil will produce parts with less material and thus less internal stress, this can effectively minimize warping in some case. Parts printed at 100% will suffer from significant warping when compared to parts printed at 25-50%. Parts should still be printed with a moderate infil (above 20%) as parts printed with a low infil will have less surface area across layers and become more susceptible to cracking.

Cracking between layers

Materials like PC require the right environmental temperature for the best results. When the environment is not controlled and consistent, residual stress will build up during the printing process and will release through the form of cracking or warping.

  • Printing PC without any internal stress can be achieved with a controlled heated chamber. With the right chamber temperature it is possible to print without any cracking.
  • If you don't have access to a heated chamber we recommend first ensuring your 3D printer is enclosed and that you are printing with the highest bed temperature that is suitable for PC. The passive heat from the heated bed will be contained in the enclosure and minimize internal stress. Once you have achieved the highest environmental temperature, the most important step is to print with the highest suitable nozzle temperature and a slower printing speed. The combination of the speed and extrusion temperature will maximize inter-layer bonding which is key to resist cracking.
  • Printing with more perimeters can increase the surface area between layers, improving the bond and reducing the risk of cracking.

Poor layer adhesion

Causes and steps to improve poor layer adhesion.

  • If the filament is under-extruding during printing there will be inconsistencies and gaps between the layer, compromising  mechanical strength and layer adhesion. It is important to ensure you are printing the PC filament at the right nozzle temperature to ensure consistent flow and to minimize drag or tension which may prevent the filament from feeding.
  • Printing with the cooling fan ON can negatively impact inter-layer adhesion. Printing with a LOW setting can be beneficial when printing overhangs in PC but for the purposes of improving inter-layer adhesion, first experiment with the cooling fan turned OFF to see if your adhesion improves.
  • If your model is printed with a lot of internal stress, the inter-layer performance of your model will be compromised. We recommend following our tips in relation to cracking.
  • Poor layer adhesion can also be caused when printing with PC that has been spoiled with moisture. When the filament passes through the hot end, the moisture erupts creating bubbles in the extruded plastic, compromising  the parts mechanical properties. If a spool of filament has absorbed moisture, it can be dried however it is important to store the PC correctly and prevent this issue from occurring.

Smell during printing

Compared to other 3D printing materials, PC can sometimes print with a noticeable smell.

Causes and steps to minimize printing odors

  • PC materials will release a noticeable smell during printing if printed too hot. Printing at lower nozzle temperatures can sometimes minimize noticeable odors when printing PC.
  • Placing the printer in a ventilated space can help to minimize odors when printing PC, odors will also be less noticeable when printing with enclosed printers.
  • Some 3D printers are equipped with HEPA / carbon filters which can help to minimize the smell when printing PC plastics.

Parts difficult to remove from platform

To print a successful print excellent adhesion between your first layer and the the bed is critical, but in some cases it can be difficult to remove models if your adhesion is too good.

Causes and steps to improve print removal experience

  • Some users prefer to apply Magigoo PC to their print bed. With Magigoo PC parts can self release when the bed cools down, making print removal easy.
  • Some print surfaces specifically manufactured for PC materials are designed to maintain adhesion with the part when the bed is heated and self-release when the part is cool. Try removing the models when the heated bed is hot or cold to see what method best suits your printing surface.

If you are printing on glass (without Magigoo PC), please always remove the part when the glass bed is HOT.

  • Your heated bed may be operating too hot or your nozzle temperature may be too close to the bed. You can try making slight adjustments to the heated bed temperature or nozzle height if this improves your user experience. Of course this is a fine balance as adhesion between the print and platform is important to achieve successful prints.

Difficult to remove supports / raft

Preventing model from fusing to supports

  • Increasing the distance (z gap / vertical offset) between the model and supports can make support removal easier.
  • If the nozzle temperature is too high, it is possible for supports to permanently fuse to the model, requiring pliers or a chisel to remove. Reducing the nozzle temperature can help prevent this from happening.
  • Printing supports with a dense interface can improve the underside surface quality of your models. If the dense interface has too many layers it can be harder to remove this part of the support. Reducing the number of dense support layers and interface infil percentage can assist with support removal.
  • Reducing the infil percentage or changing the support pattern can help improve support removal.

Preventing model from fusing to raft

  • Increasing the distance (z gap / vertical offset) between the model and raft can make raft removal easier.
  • If the nozzle temperature is too high, it is possible for raft to permanently fuse to the model, requiring pliers or a chisel to remove. Reducing the nozzle temperature can help prevent this from happening.
  • If the bed temperature is too high, it is possible for the raft to permanently fuse to the model. Reducing the bed temperature can help prevent this from happening.
  • Adjusting the first layer height and the printing speed can impact how models will adhere to the raft. For example thicker first layer heights and slower speeds can sometimes improve raft removal.

Filament Links


PC Filament Introduction
Buy PC Filaments

PolyLite™ PC Introduction
Buy PolyLite™ PC

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