3D Printer Heat Creep Explained
Heat creep has 3D printer filament melt too early in the hot end, sometimes resulting in clogs. Learn 4 simple solutions to this problem!
A Lurking Enemy
3D printing can be a fun hobby, however, there are many challenges that you can run into. A particularly troublesome area is the hot end, where many issues can occur. If you’re unfamiliar with the exact components of a hot end, it can be divided up into six main parts:
- Nozzle: The bottom of the hot end assembly where filament comes out.
- Heat block: The part right above the nozzle, where the heater cartridge goes.
- Heatsink: A component that somehow allows air to travel through.
- Throat: A part that’s often threaded and connects the heatsink to the heater block.
- PTFE tube: Teflon tubing that lines the hot end of many printers. Filament is fed through it.
- Coupler: This pneumatic (pressurized) connection piece goes into the heatsink, and the PTFE tube slides in.
The hot end assembly refers to the entire unit, which includes all of the previously-listed parts.
Filament should only melt in the area around the heater block and the nozzle, an area known as the melt zone of the hot end assembly. If it melts elsewhere in the assembly, that’s when you’ll start to have some issues.
What Is Heat Creep Exactly?
One potential problem in 3D printing is heat creep, which involves the hot end assembly, the filament, and heat. Heat creep specifically describes how heat travels (sneakily) up the hot end and melts filament too early, before the melt zone.
This problem can manifest mid-print or after a print (during cooling) but usually occurs and is noticed in the middle of a print when temperatures are highest. You can see evidence of heat creep when your 3D printed part looks only half-complete with a fuzzy top (like in the above image). You can also detect heat creep when you pull your filament out and there’s an air bubble.
All of this can ultimately lead to clogs, but keep in mind that heat creep isn’t the same as other types of clogs like basic nozzle jams.
Heat creep is more of a prevalent issue in all-metal hot ends without a PTFE-liner because they allow heat to travel easier, but we’ll discuss this more later. You’re also more likely to see it with lower quality hot ends that allow heat to pass through more easily.
In this article, we’ll go over the fundamentals of heat creep and how to solve it. We’ll first go over the causes and then some solutions, followed by tips and tricks. Let’s flow into it!
There are many causes for heat creep, but the most common ones have something to do with hot end cooling, hot end temperature, PTFE lining, and filament heating time. A problem with any can single-handedly lead to heat creep, but combined, they can also work together. Therefore, it’s important to consider all possibilities.
- Hot end is too hot: If your hot end is too hot, this can cause heat creep. That’s because the hotter the heat block gets, the more heat there is, with any excess possibly traveling to undesired locations.
- Hot end fan not cool enough: If your hot end fan isn’t on or isn’t running fast enough, there isn’t enough cooling for the heatsink and hot end assembly. This can lead to heat traveling up the hot end and melting the filament before the material reaches the melt zone. Without any cooling to dissipate heat, heat creep may occur.
- Filament is in the hot end for too long: Extra time in the hot end assembly allows heat to melt the filament before the intended melt zone, thus causing heat creep.
- Hot end design: Not all hot ends have the same capacity to deal with heat, especially in combination with other factors. An all-metal hot end, for example, might more easily allow heat to travel within the hot end assembly if other factors result in too much heat building up.
Now that we know the main reasons why heat creep can happen, let’s get to the solutions!
Solution #1: Lower Hot End Temperature
The most obvious solution to heat creep is to lower your hot end temperature. A high hot end temperature means that there’s more heat within the heat block, and excess may travel up the hot end assembly. Eventually, hot end components get hot enough for the filament inside to start to melt.
Lowering the hot end temperature means less heat will be present in the hot end. This can help prevent heat creep from causing clogs, though it isn’t a super permanent fix. And of course, you can only do so as long as you’re within the temperature range required by your material.
Solution #2: Increase Fan Speed
The next best solution is to increase your fan speed, or if you don’t have a hot end fan, add one.
Your fan speed needs to be fast enough so the filament doesn’t melt before it should. If you don’t already have one, add a small 4020 fan (40 x 20 mm in size) somewhere around the heatsink, ideally attached to or blowing towards the heatsink.
First, you should set the fan to 100% speed and make sure the heat creep stops occurring. After it does, lower the speed in increments of 10% if you experience warping, cracking, or other cooling-related print issues.
Noctua, TH3D, and CUI Devices are all brands that offer effective hot end fans. If you’re looking for a silent fan, though, Noctua is your best bet.
Solution #3: Increase Printing Speed
Another simple solution, increasing print speed, is more of a heat creep mitigation strategy. Increasing speed is usually the opposite of what you want to do for hot end jams because it can cause under-extrusion. It’s a different scenario, however, for heat creep.
Heating an object takes time. Moving filament faster through the hot end means it takes less time to reach the melt zone. By doing this, you’re decreasing the chances of filament getting hot enough to melt before it should.
You should use the same temperature with a speed of 10-15 mm/s faster than what you normally use. Consider adjusting your printing speed in increments of 2-5 mm/s until you find the right mix between proper melting and preventing under-extrusion.
Solution #4: Replace the Hot End
The final and more drastic option is to swap out your hot end for something better able to accommodate your projects.
Though all-metal hot ends are often seen as upgrades over others, they could act as a heat creep catalyst if other conditions are resulting in an excess of heat. In this case, you might consider using a PTFE-lined hot end.
A PTFE-lined hot end, along with the removable PTFE tube, provides more insulation for the filament and preserves the sub-melting temperature until the filament hits the melt zone. This solution prevents heat from getting into the hot end but doesn’t stop the problem.
All of that said, any quality hot end rated for high temperatures shouldn’t give you issues with heat creep (assuming your setup isn’t causing other issues). All-metal hot ends like the E3D V6 or Slice Engineering’s Copperhead should prevent heat creep.
Tips & Tricks
Below, we’ve listed some tips and tricks that should generally help deal with heat creep:
- Know your issue: Make sure the issue you’re experiencing is truly heat creep and not another type of hot end clog or jam. To do this, ensure that your PTFE tube is tightly matched with the nozzle, otherwise, you’ll get other types of jams. You can try replacing the nozzle to make sure the nozzle itself isn’t the problem. If you do these things and still experience issues, you’re most likely dealing with heat creep.
- Adjust one setting at a time: Adjusting multiple slicer settings or hardware configurations make it difficult to pinpoint which tweak solved the issue. You should only adjust one slicer setting and mechanical assembly feature at a time to find what’s actually working.
- Clean your hot end assembly: You don’t want other particles causing issues, so make sure you’re cleaning the hot end assembly every few prints. A dirty hot end assembly can cause more issues than just heat creep. To clean your hot end assembly, use a damp, microfiber cloth or rubbing alcohol cloth and wipe down the exterior and interior of your hot end components while they’re hot (normal printing temperature). To clean or unjam the nozzle, use a small nozzle needle and poke it through.
- Use a high-quality PTFE tube: Using a high-quality PTFE tube will mean better filament insulation inside the PTFE tube. The higher the temperature resistance, the higher the quality of the PTFE tube. A good example of a high-quality PTFE tube is Capricorn.
- Cut the end of your PTFE tube: Cutting your PTFE tube on the end every so often ensures that the end of the Teflon tube isn’t burnt or baked. This allows you to get a good fit between the end of the PTFE tube and the nozzle, helping prevent heat creep and other issues.
- Use high-quality filament: Low-quality filament tends to have an inconsistent diameter and can also cause hot end jams, so we recommend using a high-quality filament with a tolerance below +/- 0.05 mm.
- Turn off your printer after printing: Some users have noticed that turning off their printers after printing so the hot end assembly doesn’t stay heated also can help. Just make sure your hot end isn’t still being heated when you shut off your printer.
- Remove filament after printing: Another trick you can use is to remove your filament after printing. If filament stays in the hot end while it cools down, it can gradually melt higher and higher above the melt zone. You should consider removing your filament after every print, so it doesn’t melt too early and cause heat creep.
- Lower retraction: Retraction is the setting that controls how much filament is pulled out after every printhead movement. Too high of a retraction can cause the hot filament to be pulled above the melt zone and can assist heat in moving through the assembly. If you think this is what’s happening, try lowering your retraction settings in increments of 0.5 mm.
- Clean hot end fan: A dirty hot end fan can move slower and have less of a cooling impact on your hot end assembly. Occasionally clean your hot end fan with a damp microfiber cloth or rubbing alcohol cloth by gently wiping the underside and overside of the fan.