3D Printing with PETG – How does the printing temperature affect strength? || Setup & Tips


In a previous video I printed and tested dozens
of PLA specimens to find out if the printing temperature changes the strength of your parts. I got a couple of requests to do the same
investigation with another commonly used printing material – PETG. And that’s exactly what I did. Stay tuned, guten Tag and welcome to CNC kitchen. So if you print functional parts you are usually
trying to make them as strong as possible that they do not fail during usage. As I found out in one of my previous videos
it makes quite a difference if you print your PLA at 180 or 240°C. By using higher print
temperatures, the layers seemed to fuse together way better so that the adhesion between the
layers more than doubled. Obviously, there is a limit when higher hotend
temperatures start degenerating the plastic leading to worse print quality and also strength
of your parts. So around two years ago I purchased my first
roll of PETG filament which claimed to unite the good printability of PLA with the heat
resistance of ABS. Unfortunately, I wasn’t really happy with
the material at that time. It often did not stick to the bed properly
then the prints were bubbly and tuning in the setting was a nightmare. Sometime later I bought another roll of a
different manufacturer which already worked better but still was far away from the ease
of printing with PLA. After my last PLA test video I thought that
I should give it another try and if I’m already tuning in the settings for the material
I can take a look at the influence of different printing temperatures. When I get a new material I usually tune it
in the following way. I search the internet or look on the filament
itself to find the first recommendations for the temperatures. I insert the filament into the printer at
the recommended temperature and perform a calibration of the extruder. So the slicing software later relies on the
fact that, if it wants to push 10mm of filament into the hotend, really 10mm are fed into
it. This means that the control board of your
printer needs to know by how many degrees, or actually how many steps your extruder motor
needs to turn to extrude the given amount of material. So, the factor “steps/mm filament” needs
to be calibrated. You can roughly calculate this value if you
know how many steps your motor needs for one rotation of your extruder gear and if you
know the radius of this extruder gear. But everyone who has already worked with different
material groups knows that for example PLA and PETG behave differently. PLA is stiffer, so it does not get pushed
into the teeth profile of the gear as far as PETG. This means that the effective radius is bigger
and therefore you need less steps per mm as with PETG. There usually is quite a good value for the
calibration factor in your firmware, but I highly recommend to tune it for each material
group separately. This is done quite simple. I mark a given length, for example 60mm on
my filament, then I use any interface software like OctoPrint of Pronterface to extrude a
slightly smaller amount of filament, here 50mm. Make sure that the extrusion speed is not
too high, because this could screw up your results. After the extrusion is finished measure by
what amount your filament was moved. By dividing the desired extrusion by the real
extrusion, you will get your extrusion multiplier. This is the value which you put into your
slicer together with the measured diameter of your filament. If you don’t have a very exotic 3D printer
there should be plenty of profiles on the internet, or even provided for your printer
and your material type. I used the Prusa PETG profile in Slic3r and
only edited extrusion multiplier, filament diameter and the temperatures. I printed the first parts with theses settings
and finetuned the extrusion multiplier to end up with really nice print results! From my experience PETG likes to be underextruded
just a tiny bit. The only real quality difference to PLA is
the slight stringiness, which could be further optimized and the worse performance in overhangs. So now to the temperature test. As a start, I wanted to find out what the
temperature range of my PETG was, so I printed out one of these temperature towers with values
from 205°C to 280°C. So we can see that the print did not fail at any of these temperatures. Still the quality really starts to degenerating
at higher temperatures. The results seem to be okay up until 250°C
at which point you see quite a lot of bubbles forming in the print. Also the stringiness increases constantly. Overhangs printed very well all the way up
to 280°C. Bridging became really bad from temperatures higher that 250°C. The fine
details seem to be printing well up to 235°C and then gradually become more and more squished
out. So from these results I would say that the
printing temperature should be set between 205°C and 235°C but how does the strength
change with the temperatures? In order to investigate this, I printed out
a couple of tensile tests specimens from temperatures between 205°C and 265°C. Half of the specimens
were printed lying on the printbed to test the strength of the filaments strands itself
and the other ones were printed upright to test how the layers adhere to each other. I fired up my DIY tensile testing machine
and destroyed them one by one, measuring the force at which they broke. So let’s take a look at the results. The blue bars show the average Ultimate Tensile
Strength of the lying specimens, the orange bar the average values of the standing ones
which represent the layer adhesion. As expected and similarly to PLA, the strength
of the lying specimens is not significantly affected by the print temperature. The layer strength on the other side has its
maximum at temperatures of 220°C and then gradually falls off, which is different to
the PLA results. So this means, that this time we really have
a sweetspot of strength and quality because also the printing results were very good at
220°C. I have printed all of the specimens with the partcooling fan running at 50%. I turned it off for one set of specimens which
resulted in more than 25% better layer adhesion. You might be thinking “hey, why do we use
it at all?”. But if you print a detailed part without the
fan on, you will notice, that the print results get way worse at some details and the stringiness
increases. This might be a good tradeoff for some parts,
but generally I think you should have it turned on for the sake of print quality. I have also noticed during my tests and this
is also my general experience with PETG that it is sometimes just inconsistent to use. I printed one batch of specimens at a very
dry and one at a humid day. The ones printed on the humid day had significantly
less strength than the ones from the dry day. This shows that this material is susceptible
to moisture which is a downside from that material group. One thing which still confuses me is the fact
that the material is very ductile if you slowly load it in direction of the filament strands. I was not really able to break one of the
specimens because they just strained and strained! Also, if you bend a specimen by hand it will
only deform but not break. Everyone who has already worked with PETG
will know that it usually behaves quite brittle, actually even more than PLA! I am no polymer expert, so I don’t know
if that has something to do with viscoplasticity, but if I load a part by an impact force, like
with a hammer, it will shatter into small pieces without any sign of plastic straining. If anyone can explained that behavior to me,
I would be really happy to know! I am thinking about building an impact testing
machine. Maybe then I can also compare this parameter. One last thing to say: The tests that I perform
will probably not be applicable to any brand of PETG, since every manufacturer has their
own recipe for the material. Still I hope you learned something. If you have suggestions for other tests, then
please let me know. If you liked the video, please give it a thumbs
up. Consider subscribing if you don’t want to
miss more of these videos. Check out my other technical content on the
channel. Thanks for watching, auf wiedersehen and I’ll
see you next time!

100 Replies to “3D Printing with PETG – How does the printing temperature affect strength? || Setup & Tips”

  1. Very Nice video, I'd like to know a bit more about your so well engineered tests, is there any place you put them and we could discuss it ? Looking forward exchanging soon, creationsab3d , Cheers

  2. Is it possible that you can publish your findings and results in a written report? I'm a mechanical engineer and work with PETG and PLA regularly as prototyping mediums and I'd be very interrested in your results.

  3. I print in esun PETG at 240-246C with no bed fan and don't get any deformed prints and they seem very strong. From my experience if you don't use the bed fan the layers hold together much stronger. Esun stuff is great.

  4. In my experience, print speed is more important for PETG then temperature for good layer bonding. PETG doesn't like fast printing speed. While 45mm/s for normal pieces is quite decent, best printing ( especially bridging ) is around 25mm/s @ 235C ( or for example when printing precise GT2 pulleys ). Lowering print speed reduces the effects of surface tension ( the material in it's molten state right after it leaves the nozzle ) > to observe the effects of this, try extruding a small strand in air and measure it with a caliper… you'll see that the extrusion is always much thicker then the nozzle diameter. While this has limited value for normal layers, it is important for bridging.
    An even more important value for bridging ( and strength in general ) is Infill/Perimeter overlap ( I use 55% instead of the default 25% ) which makes a really big difference in quality > think of it as the surface onto which a bridge strand can attach itself.
    You're quite right about howto use the pinion teeth and multiplier adjustment….
    I'm actually quite surprised that you took the time to do all these tests and forgot to include speed….

  5. Does the temperature change automatically for the temperature tower, or do you have to change the temperature manually with every step of the tower? How do you do configure the printer if it is done automatically?

  6. In material science, the loading rate of a specimen matters in testing it's tensile properties. Tensile testers are set to a very slow loading rate for this reason. A slower loading rate causes a material to behave more ductile, and a faster loading rate causes a material to behave more brittle. That's why you can't completely rely on the tensile stress data for all applications as your component might be experiencing a fast loading rate due to a high frequency input force

  7. You are one good person on earth who is using science to carry forward 3D printing. May be some day, we will use some unit of measurement named after you (e.g. we are presently using Newton, Joules, Watt etc…)

  8. about shattering in pieces….there is one thing called impact. Impact is Force per unit time. Another is thing is called Shear Rate which is shear force per unit time. Polymers have stereoscopic structures and hence behaves differently to different kinds of forces. Also, there is something called Viscosity and glass transition temperature.

  9. PET ist known to show the effect called strain hardening. The long polymer chains orientate in the direction of applied force, if enough time is provided, and therefore increase the modulus of elasticity in this direction. If a force is applied abruptly, the chains do not have time to orientate in the direction of force impact and therefore show a lower low shock resistance.
    For the point you called "hydrolysis" – that is the wrong term. Hydrolysis is a chemical process, while the hydrophilic behaviour of PET (and any other polar polymer, especially PA) is a tendency of physical aggregation of water molecules. A lower glass transition temperature and stiffness is the outcome. Plus of the physical property change: You can dry hydrophilic polymers, e.g. in your home oven with circulating air, at 80 °C for 12h.

  10. Wäre nicht die Dehngrenze interessanter? Also Die Hooke'sche Grade 0,2% verschieben. Die Zugfestigkeit juckt ja eher weniger weil das Bauteil dann eh schon kaputt ist.

  11. Hey, you should google viscosity actually the concept you need to look for are called "Rheopexie" in german that describes that behavior

  12. Hi, würdest du sagen, dass das Filament von "Das Filament" besser ist als das von "Extrudr"? Ich habe vor einigen Tagen mit PETG drucken begonnen und bekomme einfach keine ansehnlichen Ergebnisse mit dem Extrudr Filament hin.

  13. Awesome video, I may have missed if you already did one, but if you could do a video like this for ABS that would be awesome!

  14. This is a much better way to calculate the extruder multiplier (If it hasn't already been posted by others)
    http://www.desiquintans.com/flowrate

  15. What I do know about some materials, they can display odd behaviour under loading.

    Compression shocks like hitting the material with a hammer can put excess strain on the component that then shatters, the impact force of the hammer is transferred and that transfer of energy in to the part causes it to break apart when it wouldn't normally.

    Take paper, if you apply enough pressure to a ream of paper, it will explode with some force, theirs an example online with a guy who has a hydraulic press channel and he experiments with crushing stuff.

    Well I can't wait to build mine, manufacturer sent it without the right bolts for one part… I have a clone of an i3 which I will definitely be moding.

  16. Problem with tests like this is that it assumes everything else, other settings, environment etc is constant, which they are not. Which is why its not worth the average user bothering with this, unless you are not happy with your printz of course.

  17. I only use PETG. It smells absolutely not and doesn't need a cooling fan wich I don't have (I use 15 second minimum layer time). I use a 95° C bed temperature and don't get any warping with that ever. Your retraction settings were off in this video the whole time. PETG needs more retraction than PLA. I don't get any stringing at all with 5 millimeters on my direct drive. DAS FILAMENT has put a lot of G (glycol modification) into the PET so it gets that soft. My favorite is from 3D PSP, it is a bit tougher (also cheap). The greatest difference between PLA and PETG is visible and feelable with big vases with a single or double perimeter shell. My printer is a completely custom build one for 110€ all together. It is based on the i3 design and prints magnificent. Prusa also prints everything in PETG now wich is completely right in my opinion, I guess PLA will be at some point only a niche filament. I really enjoy the pace of the video and the graphs. Maybe you could communicate the intro and outro more in line with your normal talking ;).

  18. Thats weird that you get bad overhang results from PETG. Mine are usually better than PLA. It defintally prints angled overhangs better than PLA in my experience. Often I'll go up to 50 degrees without any filament cooling and get perfect results. Ive never used Das filament PETG, but I've used at least 10 other manufactures PETG filaments, and I can't explain the top of your benchy. I have never experienced problems printing even very fine detail with co-polyesters.

  19. Slowly bending PETG will create molecular friction and warm up the area causing it to stretch.
    If you bend it FAST, it wont be able to warm up quick enough. It will brake instead.

  20. At the beginning he says " It did not stick to the bed properly " LOL Maybe it was – I didn't adjust the bed height properly would be a better way to say that. It bubbles / maybe I had the temp/fan settings off . LOL I have torn many sheets of adhesion promoters trying to get my Petg prints off the printer. I found using glue stick to lesson the adhesion works well with PETG tho. First I adjust the Z height up as much as possible though. I rarely use any of my PLA now because after trying PETG and seeing how much more flexible/less prone to breakage it is ,I try not to use PLA for anything of importance. Glass or mirror with gluestick as a adhesion lessoner works the best for me now. Seriously CNC Kitchen does a great job of building and testing all this data in this video and his videos are very professionally done and have helped me a lot.

  21. Thanks. Having stringyness and bridging issues with PetG. Now I will lower the temp. Thank you. I'd be interested to know about HIPS and Conductive and flexible PLA too. I'm finding the flexible hard to work with with Bowden and Direct drive. Thanks again for your help and scientific attitude.

  22. Hello, you were wondering why it bends under low load and shatters under high energy load perhaps this material works similarly to non newtonian fluids that are fluid with not much energy applied to them and act like a solid when a strong force is applied because the atoms lock up. I very well may be wrong but that was just an idea that crossed my mind. Thanks for the very informative video and have a nice day!

  23. Im sorry but the way your tone changes at the end of each sentence is a complete distraction and for myself and several others, distracts from the entire point/purpose of the video.

  24. The G in PETG is Glycol.
    It's made from corn starch, which is a non Newtonian substance when it's in fluid form.
    It might be what makes the material act that way.

  25. Polymers are generally viscoelastic, which means it exhibits both elastic properties (like solid) and viscous properties (like fluid). At low strain rate, material elastic properties will govern (e.g: pull it and release before it yields, and it goes back to original shape – like metal). However, at high strain rate, material viscous properties will govern (e.g: stress depends on velocity, not just deflection like in the elastic model) There are also temperature dependent properties as well, so testing polymers in "apples to apples" scenario can be very tricky.

  26. If Polyesters or Polyamides absorb water, the water acts as a kind of lubricant between the polymer chains, just as plastisizers making PVC soft. That's why your specimen kept straining as the polymer chains could glide off each other and align in the direction of the applied force. Materials usually behave differently when strained slowly (tensile testing) or very fast (impact testing). Usually your material shows higher strengths the faster you strain it on your tensile testing machine. The polymers have no time to react to the force so they show a bit higher resistance resulting in a higher tensile stress for example 10mm/min compared to 5 mm/min. Although there is also the effect of extreme polymer chain alignment after slow stretching which results in extremely high tensile strengths. (For examlpe UHMWPE Fibers or High strength Polyester Fibers). Impact is a very high strain rate, so the viscoelastic material has almost no time at all to adapt to the applied force thats why it breaks.

  27. Short question,

    Why is the ultimate tensile strength lower than at the pla test?
    I always thought it would be the other way around and the data sheets claime the same. Thanks for an answer. Greetings from Germany

  28. That description of the material extruding different amounts Above the extruder makes no sense. That hob moves the plastic the same unless the filament is slipping or grinding.. that is a bigger issue than your multiplier. Once that step figure is matched to your diameter filament, that should be the same for ALL filaments of the same diameter..

  29. You should do one more test!
    3D print a Thread and see how easily it can be moved/how „sticky“ it is. I noticed huuuge differences there, influenced by multiple factors. Warping, Temperature, Fan etc but most importantly: material.
    PETG for example is super sticky.

  30. Although I'm not a plastics expert, I assume that PETG is very similar to PET, in which case you should bear in mind that when you stretch PET, its yield strength increases. This is the reason that PET bottles (soft drinks etc) are so strong. They are made as small injection moulded bottles, then blown out to full size and become considerably stronger in the process. Another example is the plastic film used to hold 4 packs or 6 packs of beer together. If you stretch a length of it, the material necks down but does not fail there. As the cross sectional area is less than the unstretched material but it supports the same tension, you can see that the yield stress is greater. I think you are seeing this increase in yield strength when you test your samples. It's one of the potentially interesting benefits of PETG over PLA etc.

  31. what about bed temperature? online resources have a very wide range of suggestion from 50 to 120. great help that is.
    on my first layer everything sticks fine, except this tiny little feature that starts as a U and it just loves to stick to the nozzle and bunch up making big blob bringing everything with it and ruining the next feature. it was running fine the first 2 times I ran the print and now I can't get it to work for the life of me.

  32. Thank you. Can you test ABS more? I am starting a business and I use ABS to make larger parts that I bond with acetone. I would love more information on how to make my ABS parts stronger. I make accessories for wheelchairs and the parts need to be a strong as possible.

  33. Great Video. Just wonder what camera hold you are using which I saw in your Video sticked to you headbad: Thingivers?

  34. Strain rate. The material fails more violently when loaded quickly, and never really 'ruptures' when loaded slowly. Usually the difference isn't this pronounced… Since you have a tensile tester, this could be another thing to look into!

  35. Great video! But, its devoid of practical or instructional information, making it completely useless as a resource for the practical use of PETG in an actual printing application. Leave it to a German to overexplain a topic, in the most dry, and technical way possible. :-p

  36. Hi Stefan,

    have you ever heard of Extrudr's GreenTec Pro filament? It is a filament which should be dimensionally stable up to 160 ° C. Could you also strap it on your torture bench? 😉 I like to print with it when prints have to endure a bit more temperature. I do not see the 160 ° C reliability promised by the manufacturer, at least for my area of application (Graphics Card Modding / Heatsink Retention Kits) :-/
    If I'm apply some mounting force to my Prints and the aluminium heatsinks the material deforms already at 80-90°C. Most likely I don't understand fully what the VICAT A (VST) testing method means.

    Both topics: GreenTec Pro and the true meaning of VICAT A (VST) Testing would be great next videos! 🙂

    Liebe Grüße und Danke für die tollen Videos 🙂

  37. When comparing MPa between your PLA and PETG charts, the PLA maxes at 42.4 while PETG maxes at 32 (Z layer strength). Is there a reason that the PETG is weaker in your tests? I was under the impression that PETG is stronger than PLA.. which was why I was going to start printing PETG.

  38. What is that blue cap on 2.14 minutes and the black cap … where can you get these and are these used for fillament going wrong ?

  39. The difference in "way" it is broken is because of the speed. When you are bending it or slowly pulling it, the polimer chains and crystal structure has time tu adjust and reorganize so that it doesn't shatter to pieces, but if it is impacted in a short amount of time it can't reorganize but it needs to absorb all the energy so it shatters. So, one is force over "long" period of time, and the other is force over short period of time or the "impuls"

  40. Nce findings! It would be nice to show the standard deviation of your results on the graphs to have an idea of the variability.

  41. Lots of people say PETG is the new PLA and rave about how easy it is to print with and how good the final products are. In my experience, printing ABS or even Nylon is easier than PETG. I've tried many times to make PETG work. On 3 different printers, 4 different brands of PETG and with every imaginable setting under the sun. Results are never as good as what i can get from PLA.

  42. Look for the term "anti-thixotrope" for an awesome delve into the science of shear hardening! 😀

  43. this is a very interesting concept. as mentioned below the most impactful setting for pteg is the speed, but the temperature surely has some effect on the ability to bond layers. interesting to see the difference. thanks!

  44. The problem with PETG is that it has both a low specific heat and a relatively high thermal conductivity. This means it cools down very quickly and printing it in a cold room and/or with too much cooling, will definitely reduce layer adhesion. This may explain your varying results over time. An easy way to see when you're cooling PETG too much is to see when the surface starts to lose its shine. If it does, it's cooled too quickly and layer adhesion will become bad.

  45. Huge congrats on your work. I'm new to 3d printing, but since the beginning I'm mainly interested in doing structural parts, so your videos are of great help to decide on the right settings for getting good strength and stability. You rock!

  46. Does the ambient room temperature have any effect on hot end temperature? And which filament did you find to be least affected by humidity? Thank you.

  47. I'd like to see the Polymaker Polymax PETG compared to regular PETG and CF PETG. Different types of CF PETG compared would be interesting as well. There are some that I believe are no better than regular PETG. Polymaker actually gives the Tensile strength numbers for their filament but many companies do not.

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