Teach lesson
3D printing: how does extrusion temperature affect print quality?
Students use the 3D Printing remote lab to print the same PLA part at five nozzle temperatures, compare the real lab video and the lab's verdict cards, rank the results, and recommend the right printing temperature.
Learning Outcomes
State a hypothesis about which extrusion temperature gives the best print quality in PLA.
Run a controlled experiment changing only the temperature while keeping the model, orientation, layer thickness and supports fixed.
Observe and compare the lab's real results (the print video and the verdict cards) and rank them by quality.
Identify the suitable temperature range and the failure modes when the temperature is too low and too high.
Relate those failures to the behaviour of PLA (melting, flow and degradation) and write a justified manufacturing recommendation.
Student activity preview
Activity Content
Preview only. In a class session, students can fill in responses and submit their work to the teacher.
1 · Before you start: your prediction
8 min
An FDM (fused deposition modelling) 3D printer builds parts layer by layer: a thread of plastic called filament is fed into a hot nozzle, where it melts and is pushed out as a very thin strand that is laid down line by line. Pushing the melted material through the nozzle is called extrusion, and the extrusion temperature (the nozzle temperature) decides whether the plastic melts properly and flows out cleanly. The plastic used in this lab is PLA, the most common material in educational printers.
In this experiment you will always print the same part (a letter A) and you will only change the temperature. To keep the comparison fair, the other lab options stay fixed:
- the orientation (how the part sits on the print bed): always Top;
- the layer thickness (the height of each plastic layer): always 0.15 mm;
- the supports (extra material that holds up overhanging parts): always No.
That way, if one print turns out better or worse than another, the only possible explanation will be the temperature.
The test part
The lab's test part: a letter A. This image is the 3D model the lab uses (a drawing, not a photo). You will always print this same part and only change the nozzle temperature.
Which nozzle temperature do you think will give the best print quality with PLA?
Explain your choice (2–3 sentences). What do you think will happen to the PLA if the nozzle is too cold? And if it is too hot?
2 · Experiment: print while changing only the temperature
20 min
You are going to run the same print five times, once for each available temperature, without touching anything else. For each case, on the Observation tab, the lab gives you two things to use as evidence:
- the real video of the print, which you can watch from three cameras (a front view, a perspective view and a close-up view): focus above all on how the part turns out at the end of the video;
- the temperature verdict card: the lab's message that tells you whether that temperature is correct, too low or too high, and what happens to the material. You will find it under the video, in the verdict table (it has one column per setting: orientation, thickness, temperature and supports); the column you care about is the temperature one.
How to move around the lab
The lab is organised into four tabs, in order: Introduction, Part settings, Printer settings and Observation. Heads-up: the lab labels two tabs in a row with the number "3" (Printer settings and Observation), so follow the order and name of the tabs, not the number.
Open the 3D Printing lab
Open the 3D Printing lab from the activity.
On the Part settings tab the model is already fixed (a letter A; you do not choose it): under the orientation chooser, select Top and confirm it. Then continue to the printer settings.
On the Printer settings tab, under the layer-thickness chooser, select 0.15 mm.
Under the supports chooser, select No. Heads-up: the lab starts with supports set to Yes, so you must change it to No.
Under the material-temperature chooser, select the first one: 140 °C. Then continue to observation.
On the Observation tab you will see a summary of your configuration and the video from three cameras (front, perspective and close-up). Start the print. The video starts at 5×; use the speed control (1×, 5×, 10× or 15×) so you do not have to wait, and drop it back to 1× to look at details.
When it finishes, look at how the part turns out in the video and read the temperature verdict card (in the verdict table, below the video).
Record both things in the observation table (further down this page).
Repeat for the other temperatures: go back to the Printer settings tab, change the temperature (170 °C, 200 °C, 230 °C and 260 °C) and, before observing, check again that supports is set to No (the lab may show Yes again when you return). Then start observation again. Do not change the orientation or the thickness.
Observation table — quality by temperature
For each temperature, copy in your own words what the temperature verdict card says, and describe how the part turns out in the video (did the letter form? does it look smooth, rough, incomplete, with defects? does any material come out at all?). Do not invent numbers or scores: describe what you observe.
| Temperature °C | What does the verdict card say? | How does the part turn out in the video? |
|---|---|---|
Compare the two extremes. At 140 °C, what happens to the part, or to the material coming out of the nozzle, in the video? At 260 °C the part does get printed, so here focus on what the temperature verdict card says about the material. Describe what you observed in each case; do not explain why yet.
3 · Compare and rank the results
8 min
Now rank the results without looking at a solution. Use only your observation table: what you saw in the video and what the temperature verdict card said for each case.
Ranking — from best to worst quality
Rank the five temperatures from best to worst quality according to what you observed (the best in position 1). On each row, write in a few words why it takes that position, citing your observation table (what you saw in the video or what the card said).
| Position | Temperature °C | Reason (what you observed) |
|---|---|---|
Based on your observations, which temperature (or range of temperatures) gives the best quality with this PLA? Does it match your prediction from step 1?
4 · Explain: the reason in the material
9 min
You now know what happens at each temperature. Now explain why, thinking about how PLA behaves as it passes through the hot nozzle.
When the temperature is too low, the lab states that the material does not melt properly and can even clog the nozzle (at 140 °C nothing comes out at all). Using the idea of melting, explain why PLA that is not hot enough cannot form a quality part.
When the temperature is too high (230 °C and especially 260 °C), the lab states that the material degrades. Explain why overheating the PLA also worsens quality, even though the plastic is indeed melted.
Put the two ideas together: why is there an intermediate range of temperature that works better than the cold and hot extremes? (Hint: to print well, the plastic has to melt enough to flow, but without degrading.)
5 · Conclusion: your manufacturing recommendation
5 min
Imagine a classmate is about to print this same part in PLA and asks you for advice.
Which temperature do you recommend for printing this part in PLA? Base it on your ranking, not on a personal preference.
What failures appear below and above that recommended temperature? Cite at least two temperatures from your table.
Explain why temperature affects quality, using the ideas of melting and degradation of PLA.