3D printing is an undeniably fun and rewarding activity — but it does come with its own unique set of challenges. A common area for hiccups is the hot end, which can crucial for the accuracy and quality of a 3D-printed object. This system includes six components:
- Nozzle: The base of the hot end assembly from which filament emerges.
- Heatsink: The region just above the nozzle where the heater cartridge is located. A heatsink is a component that allows air to circulate.
- Throat: A typically threaded component that links the heatsink to the heater block.
- PTFE tube: Many printers’ hot ends are lined with Teflon tubing. It is fed with filament.
- Coupler: This pneumatic (pressurized) connecting piece is inserted into the heatsink, followed by the insertion of the PTFE tubing.
The “hot end assembly” is the whole unit, which is made up of all the parts we’ve already talked about.
Heat creep is a common problem in 3D printing that occurs when the filament starts to melt inside the hot end assembly outside of the melt zone. This is an area around the heated block and nozzle where it should exclusively be melting as it works with the assembly to create a printable object. If it melts anywhere else, you’ll start experiencing some difficulties.
In this article, we will discuss what heat creep is, its origins, a range of treatments, and some pre-, during-, and post-printing suggestions for dealing with it. Let’s get started!
Understanding Heat Creep in 3D Printing
As the name implies, it describes how heat slowly and slyly creeps up the hot end, ultimately melting the filament too early before it should reach the melt zone.
It occurs when too much heat travels up to the hot end and melts the filament too soon, leaving your part incomplete and fuzzy. Obvious signs of heat creep include finding air bubbles in the filament or half-finished parts with fuzzy tops, which you would likely spot during your print. Heat creep can start during a print or after it has completely cooled off; however, it typically reveals itself when temperatures are highest.
All of this can eventually result in clogs, but keep in mind that heat creep is different from various kinds of clogs, such as nozzle jams.
The issue is particularly common in all-metal hot ends without a PTFE liner, as these do not contain the materials that typically keep the heat from transferring too easily. We’ll talk about this more in-depth later, though. It also happens more often with hot ends that aren’t as good and let heat pass through more easily.
Before we talk about what can be done, let’s talk about what might cause heat creep.
Contributing Factors to Heat Creep
While there are many causes associated with heat creep, the most frequent ones relate to hot-end cooling, hot-end temperature, PTFE lining, and filament heating time. Any of these problems can cause heat creep on their own, but when they all happen at once, they may just be bad. Therefore, it is key to deliberate through all possibilities carefully in order to effectively eliminate heat creep from happening.
- The hot end is too hot: Having an overheated hot end can create problems with “heat creep,” where the excess heat radiates towards undesired areas in a 3D printer’s system.
- Hot end fan not cool enough: Heat creep may also become an issue without adequate cooling. Ensuring that your hot end fan is on and running at a sufficient speed is essential for proper cooling of the heatsink and hot end assembly. Heat travelling up the hot end can result in melting filament before it even reaches the melt zone, leaving 3D printers with little to no material to print with.
- The filament is in the hot end for too long: Heat creep can be caused due to an excessive amount of time spent in the hot end assembly, allowing the filament to fully melt before reaching its intended melt zone.
- Hot end design: Despite the similar name, not all hot ends are created equal. Different designs and varying materials used to make them can give them different capacities when it comes to dealing with high temperatures. A perfect example of this is an all-metal hot end which has a higher thermal conductivity than a plastic one hence allowing heat to travel within the assembly more easily if other factors result in too much heat building up.
Now that we understand the primary causes of heat creep, let’s move on to the solutions!
Solution #1: Reducing Hot End Temperature to Address Heat Creep
One of the most straightforward solutions to heat creep is to lower your hot end temperature. This ensures that there won’t be too much heat in the hot end, helping to prevent any melting of the filament within the assembly.
It should be noted though that this isn’t an ultimate solution and it is essential that you choose a temperature for the hot end that complies with the requirements of your chosen material. By lowering your hot end temperature you are entering into a balancing act between heat creep prevention and meeting material criteria, which means test prints can be incredibly useful.
Solution #2: Boosting Fan Speed to Mitigate Heat Creep
The next best thing to do is to speed up your fan or add a hot-end fan if you don’t already have one. You should go for a small 4020 fan (40 x 20 mm), and attach it to or blow it towards the heatsink.
Initially set it up to run at 100% speed so that the filament doesn’t melt before it should. When the heat creep stops occurring, then you can reduce the speed in increments of 10% till you find a good balance between cooling and functionality.
Brands such as Noctua and CUI Devices stock great options for fans, but if noise isn’t a major concern for you then Noctua is also worth considering for its silent solutions.
Solution #3: Raising Printing Speed to Counteract Heat Creep
Another effective way to prevent heat creep is Increasing print speed. Though increasing speed may not be the best choice when it comes to dealing with hot-end jams as this could lead to under-extrusion, it is an effective technique when trying to prevent heat creep. This works by reducing the amount of time that filament spends in the melt zone, thus decreasing its chances of becoming hot enough to melt before it should.
If you decide to try this method out then the ideal printing speed should be 10-15 mm/s faster than normal, thereby ensuring that the melt is cooled quickly before it can settle down and create an undesired effect. It is recommended to adjust your printing speed in small increments of 2-5 mm/s until you find the beneficial combination between melting and reducing under-extrusion.
Solution #4: Replacing the Hot End to Fix Heat Creep
The last and most extreme option is to switch out your hot end for one that can handle your projects better.
All-metal hot ends are known to act as a catalyst for heat creep, which can cause clogging and jamming troubles. In this case, you might want to explore options such as PTFE-lined hot ends that are designed to provide excellent thermal isolation while also reducing plastic oozing or stringing during extrusion.
This preserves the sub-melting temperature until it reaches the melt zone, however, it does not necessarily address the overall issue. By using this kind of insulation along with a removable PTFE tube, heat is prevented from entering the hot end and more accurately kept to its required level.
Fortunately, high-quality hot ends today are designed and engineered to combat this issue straight out of the box. Take for example the E3D V6 or Slice Engineering’s Copperhead hot-end designs – these feature all-metal constructions which greatly reduce the risk of heat creeping up through your printer’s nozzle.
Tips & Tricks
Useful Tips and Tricks
Here, we’ve compiled a list of tips and tactics that should help you manage heat creep:
- Know your issue: To make sure the issue you’re experiencing is heat creep and not another type of hot end clog or jam, it is important to ensure that your PTFE tube is tightly matched with the nozzle. As a precautionary measure, replacing the nozzle could be considered; this way, you can double-check if the nozzle itself might be causing the issue. If these points are checked off and problems persist, it’s most likely an indication of heat creep.
- Adjust one setting at a time: If multiple slicer settings or hardware configurations are adjusted at once, it can be difficult to determine which changes actually solved the issue. The best approach is to adjust only one slicer setting and mechanical assembly feature at a time and then test the result before tweaking anything else.
- Clean your hot end assembly: Keeping your hot end assembly clean is one of the most important parts of 3D printing – and it has a much bigger impact than just preventing heat creep. A dirty assembly can cause poor layer adhesion, inconsistent extrusion and even nozzle jams. To get the best results from your printer, make sure you’re cleaning the exterior and interior components with a damp microfiber cloth or rubbing alcohol cloth every few prints. When it comes to removing any build-up in or around the nozzle itself, a small nozzle needle inserted gently should do the trick.
- Use a high-quality PTFE tube: High-quality tubes guarantee better insulation for filaments, especially if the temperature resistance goes up. Capricorn’s PTFE tubing is a great example of high-grade material that offers superior insulation and protection even in extreme temperatures.
- ut the end of your PTFE tube: Cutting the end of the tube every so often is an important part of that maintenance. Doing so makes sure that the end remains unburned and unbaked, which creates a solid fit between the Teflon tube and the nozzle. This ensures a tighter seal and helps to prevent heat creep and other common issues associated with 3D printing.
- Use high-quality filament: Low-quality filament can have inconsistent diameters, meaning your prints will suffer in accuracy, reliability, and structural integrity. Additionally, jams are common with low-quality filaments because they cannot produce the same clean melts as high-grade materials. A filament tolerance below +/- 0.05 mm is preferred if you want reliable consistent results.
- Turn off your printer after printing: Turning off your printer after a print may be the simplest way to extend the lifespan of your hot-end assembly and prevent wear. Many users have reported longer periods of consistent performance from their hot ends when this method is employed, making it an easy step to consider in any printer maintenance plan.
- Remove filament after printing: To avoid filament melt-up or heat creep, it is wise to remove the filament from the hot end after every 3D printing job. Otherwise, the remaining filament could reach the heat zone and proceed to slowly melt up to a point where it clogs and forms air pockets that can affect future prints.
- Lower retraction: Retraction is the parameter that controls the amount of filament withdrawn from the nozzle after each printhead movement. If the retraction is set too high, there is a chance that the heated filament will be pulled over the melt zone, causing extra heat in the model. The best course of action is to lower your retraction settings in increments of 0.5 mm until you find the ideal level for your assembly.
- Clean the hot-end fan: While a clean hot-end fan is crucial for optimum hot-end performance, it is often overlooked. If not routinely kept clean, debris build-up on the fan can cause it to slow down and make it less effective in cooling the hot end assembly. To prevent this issue, occasionally clean your hot end fan with a damp microfiber cloth or rubbing alcohol cloth.
Experienced Project Engineer with a demonstrated history of working in the field of Product Design & Development industry in Mechanical Engineering. Skilled in 3D Printing and Re engineering Technologies with CATIA V5 , Materials Science, Finite Element Analysis (FEA), Mimics, ANSYS Workbench and Casting Simulation software. Strong engineering professional with a Master’s Degree focused in Industrial Metallurgy from PSG College of Technology, Coimbatore.