3D Print Warping- What Causes it and How to Avoid It
If you’ve been enjoying your 3D printer for a while, you probably created a few warped models. It’s always frustrating when that happens, but don’t worry, it’s one of the most common 3D printing issues you’ll encounter and sometimes you just can’t escape it.
Fortunately, there are several things you can do to prevent warping and to maximize the chance of printing a successful model. Everyone has to go through a few failures before finding the best settings, but once you do, it’s smooth printing from thereon. Just keep in mind that those settings heavily depend on the material you use and your setup. So, if you make sure your settings are within the filament’s parameters and you adjust the warping-causing settings, you should end up with a satisfying 3D print.
But if you’re a beginner reading this, you probably think warping is just a slight deformation of your model. That’s not always the case. Sometimes you can end up with a completely unusable print or a design that has damaged sections. It all depends on the severity of the warping. That’s why it’s always a good idea to go through a checklist and make sure everything is within specifications and something goes wrong, start troubleshooting step by step.
Warping is frustrating if you don’t spot it in time and you’ll waste precious time and material. Besides, once the model warps there’s not much you can do about it other than starting over. So let’s do everything in our power to understand warping and how to prevent it.
What is warping?
As mentioned, warping is one of the most common 3D printing issues. But before you can do anything, you need to understand what the term means. Warping refers to any kind of deformation of the model that involves upward or directional curling or the shrinking of corners. When warping occurs, sections of the model will move away from the print platform while the model is still being printed. This effect usually causes upward curling and sometimes you won’t even notice it until the parts of the model fully detach themselves from the platform. Once that happens, everything starts going downhill.
Warping usually happens with large models or sections, especially when working at really high temperatures. For instance, ABS is more likely to warp because it has a higher melting point and we need to use high temperatures. Why does that happen? The main reason is the material itself. That’s how plastic works. Once it cools off, it shrinks, so when the layers cool off at a large temperature difference we can end up with warped plastic. The cooling process should be gradual for this reason, otherwise, the material shrinks too quickly. For example, ABS filament melts at around 230℃ and it shrinks at close 2% when it reaches ambient temperatures. The shrinkage is even more extreme when working with large models or parts. That’s when we start measuring the difference in millimeters, not just in barely noticeable percentages, so it’s easy to visually notice the shrinkage. At that point, the model might separate itself from the build platform.
Looking with frustration at a warped model is part of the experience and everyone goes through it. Remember that and keep on learning and gathering more experience.
Now, let’s go into a bit more detail.
How does it happen?
Most of the time, when working with an FDM printer, you’re going to use some kind of thermoplastic material. As mentioned earlier, plastics shrink when the temperature goes down. Changing with the temperature is a basic characteristic of this type of material.
As you probably already know, the plastic filament is heated to a high enough temperature until it melts. The printer can use it when it goes a bit beyond the melting point because that’s when it turns into a liquid. The liquid plastic is then extruded through the nozzle and deposited on the print bed by following specific patterns. Therefore, when the material turns into a liquid, it expands. As it comes into contact with the air and the print bed, it cools off to solidify and form the model. However, when the following layer comes through, the layer under is cooler. This is where we might have a large temperature variance and one layer will shrink at a faster rate. When that happens, the previous layer will lose its hold onto the plate and it will usually curl up at the corners. This is especially bad when it happens in the middle of the print and you realize you wasted a lot of material on something that isn’t usable. Don’t despair, you gain experience with every unsuccessful print!
Now, you’re probably thinking that all you need to do is maintain the temperature at the same level throughout the printing process. That’s true in theory, but in reality, we can’t keep the temperature that steady. What we can do is keep the temperature within the safety margins to avoid warping. Let’s go into more detail because maintaining the right temperature is just a small piece of the puzzle.
How to prevent warping
We already discussed that temperature variations and differences are the main cause of warping. Keeping the temperature at the right level is crucial and we should focus on that, but there are other factors to consider as well. Some of them influence our temperature control either negatively or positively. 3D printing is a complicated process, after all, so let's explore some of these common methods of preventing warping.
Improving the print surface adhesion
The latest 3D printers are designed with build surface adhesion in mind. However, manufacturers can’t guarantee the quality of adhesion because it depends on the materials we use. Some plastics will adhere to the build surface easily at low temperatures, while others require high temperatures and constant observation. This is where you need to pay attention to the technical specifications of the material and the guidelines provided by the manufacturer or distributor. Always read the specs and follow them when setting up the printer.
But sometimes, no matter what we do, the material is stubborn and won’t stick, so we’ll have to use various adhesives like a PVA glue stick or hair spray. Take note that these same adhesives will also strengthen the first layer, which in turn improves the quality of the print. That being said, here are the two most commonly used adhesives:
- Hair spray: This generic household product works surprisingly well. It helps the material stick to the print surface but it also makes it easier to remove once we’re done printing. We need to achieve this balance, because if we have too much adhesion we may end up destroying the model when we remove it from the print bed. Fortunately, hair spray does a good job balancing things out because it works with most filaments. Alternatively, you can use professional sprays designed for 3D printing.
- Glue stick: Another common household item, the PVA glue stick improved print surface adhesion and it helps the first layer stick properly. This is probably the most popular adhesive used by 3D printing enthusiasts. However, there are some professional formulas specifically designed for 3D printing, so if you have the budget, you should look them up. But a generic glue stick will work almost as well. All you need to do is deposit a thin layer of glue on the print bed. Just make sure to test it out on filament samples because some materials will require less glue.
Leveling the print surface
Since warping is often caused by a lack of good adhesion, you need to make sure the first layer is properly deposited on the build plate. For starters, you need to level the surface because the distance between it and the nozzle has to be just right. If the distance is too great, then the plastic has too much time to cool off until it reaches the plate and it won’t stick.
If bad leveling is the reason why your models don’t stick, start adjusting the height in small increments and perform a few tests. Once you think you’re ready, perform a live test by printing a skirt in two or three layers. This way you won’t waste much material and you’ll get the chance to perform finer adjustments during the printing process. Additionally, you can print the test skirt away from where your model will be printed so that you can start your project right after the testing phase is complete.
Heat the print surface
As mentioned earlier, temperature plays a huge factor when it comes to warping, as well as adhesion. So try using a heated build plate. In most cases, this fixes the warping issue because the temperature variation of the plastic is much smaller. By heating the plate, the material won’t shrink and warp or crack all of a sudden.
Ideally, the build plate should be kept at a temperature that’s just under the plastic’s solidifying point. This way we can ensure proper adhesion with the plate. Just make sure you double-check the temperature ranges for the specific filament you’re using because each material has different melting and solidifying points. Using inappropriate temperatures can damage or weaken the material.
Ensure proper cooling
3D printers use cooling fans to lower the temperature of the extruded filament and solidify it. This cooling system is a must-have because they help manage the temperature needed to correctly set each layer. However, too much cooling will cause the model to warp. So check the cooling settings and make sure the fans are operating within optimal margins. If they aren’t, make fine adjustments and test them out.
Another solution is to make sure you get the foundation of the model as close to perfect as possible. That can be done by turning off the print head fans while the first layer is being printed. This way it will stick properly to the plate. Afterward, you can increase the cooling rate gradually as the layers progress. This can be easily done in the printer’s software. By preventing excessive cooling you will also prevent warping.
Adjust the settings of the initial layer
The first layer is the foundation of the model and if it doesn’t turn out well, you’ll probably have to deal with curling corners. That’s why you should adjust and fine-tune the first layer settings. While there are several parameters you can tweak, in the case of warping the most important ones are the first layer height and speed.
To get better adherence and reduce the chance of warping you should increase the thickness of the foundation. A thin base layer doesn’t stick so well to the print surface. As for the speed, it shouldn’t be set too high. Printing the first layer at a high speed will make it follow the nozzle as it won’t stick to the plate. Time is required for a good adhesion otherwise the nozzle will drag the molten filament and make a mess of your model.
As always, make small adjustments and run tests after each one. Printing a few layers with different parameters is cheaper and less time-consuming than printing a warped model.
Remember that 3D printing comes with many challenges and part of the fun is to overcome them. So look at them with excitement because they offer you the chance to learn and gather more experience. The more learning opportunities you have, the better your future models will become.
You might feel frustrated at first when you encounter the warping problem because it has multiple causes. What you should do is check each possible cause until you find the actual culprit. Basic troubleshooting is part of the job. But with enough determination, and a little help, you’ll find the problem and solve it. So start (or restart) going through this list of causes and solutions and make your own handy checklist.