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!

Causes

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.

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.

Retrieved from: https://all3dp.com/2/3d-printer-heat-creep/

By: Jackson O'Connell

How to Fix 3D Printing Heat Creep: 4 Simple Solutions