Hello Machine Bros!
This time I want to talk about two very common problems that occur in 3D printing, warping, and cracking. We will explain to you why they occur, tips to prevent them, solutions, and much more!
If you have been 3D printing for a long time, experimenting with several filaments, you have realized that there are materials with which it is easier to 3D print than others.
The ease with which it is 3D printed with a certain filament depends on how prone it is to suffer warping and cracking.
What is Warping and Cracking in 3D Printing?
In 3D printing, warping and cracking are related to the thermal stress of the material, in this case the 3D printing filaments, which is nothing more than the set of stresses that occur internally in the model due to thermal contractions.
When the adherence of the filament to the printing bed is not good, the model tends to detach from it. Especially, the corners of long models come off.
This problem is what we know as warping.
Now, when we observe that this same problem occurs is between the printing layers, it is what we know as cracking, due to this phenomenon the adhesion of the material between layers is compromised.
In general, both drawbacks occur due to the same factors, what usually differentiates one from the other is that in the case of warping we will observe that the problem occurs with reference to the printing bed, and cracking will be observed between the layers of the 3D printed piece.
In materials science, there is a physical property that numerically represents how much a material contract or expand as a function of the temperature changes to which we expose said material, it is known as thermal expansion.
The coefficient of thermal expansion is the value that explains how pronounced this effect is in a certain material and is the quotient of the relative longitudinal or volumetric change between the temperature variation.
It is important to know this because in this way we can conclude that a filament with a higher coefficient of thermal expansion will be more likely to suffer from warping and cracking than a filament with a lower coefficient of thermal expansion.
To give you an example that shows that this is true, we will use two materials that are widely used and known in the world of 3D printing.
On the one hand, we have PLA with a linear coefficient of thermal expansion (CLTE) of 7.5, a material that does not suffer deformations or cracks.
On the other hand, we have ABS with an CLTE of 11, which we know is quite prone to deformations and cracks.
NOTE: The CLTE values are expressed in 1×10-5/°C
For general culture, we would like to mention that most materials tend to expand as we supply heat and otherwise contract, but there are materials that behave in reverse, that is, they contract as we supply heat and expand otherwise.
These materials are said to possess negative thermal expansion.
The filaments that we commonly use in 3D printing (PLA, ABS, PETG, TPU, Nylon, ASA, PC) are made from materials that behave in the first way we mentioned (they expand by supplying heat and contract by exposing them to lower temperatures).
As we already know, materials contract or expand depending on the temperature to which they are exposed, so the greater the temperature changes, the greater the dimensional changes.
It is extremely important to know this because it indicates that there is another variable that affects to a greater or lesser extent the possibility that our 3D print suffers from warping and/or cracking.
We are talking about how big the temperature change will be in the filament when leaving the extruder and coming into contact with the air and the heatbed.
All this translates into that the filaments that require higher temperatures to be melted will be more prone to warping and cracking, this due to the greater the temperature difference that will be between the three variables mentioned (the extruder temperature, the temperature of the environment and the temperature of the heated bed), therefore, the greater the dimensional changes that this material will undergo.
|Material||Extruder temperature °C (°F)||Bed temperature °C (°F)|
|PLA||195 – 220 (383 – 428)||50 – 70 (122 – 158)|
|ABS||215 – 250 (419 – 482)||100 – 110 (212 – 230)|
|PETG||225 – 250 (437 – 482)||75 – 90 (167 – 194)|
|TPU||210 – 245 (410 – 473)||50 – 75 (122 – 167)|
|Nylon||220 – 270 (428 – 518)||70 – 100 (158 – 212)|
|ASA||240 – 260 (464 – 500)||100 – 110 (212 – 230)|
|PC||260 – 310 (500 – 590)||100 – 120 (212 – 248)|
Due to the aforementioned, when 3D printing with filaments that require high temperatures to melt (for example, PC), it is advisable to have a heated bed capable of reaching higher temperatures, and also a closed printer.
Is important to have a closed 3D printer so the air temperature inside the 3D printer’s working area is kept as constant as possible and at higher than normal temperatures.
In addition, with a closed 3D printer, the flow of air currents that can suddenly and drastically vary the temperature of the filament when leaving the nozzle, or the 3D printed model is prevented.
There is another value that tells us at what temperature a polymer decreases its density, hardness, stiffness and its percentage of elongation.
This value is known as glass transition temperature (Tg).
When the material is molten is not affected by thermal contraction. But when the material solidifies and it is at a temperature lower than Tg, it is when thermal contractions begin to cause thermal stress.
The higher the Tg of a material, the higher the temperature that will have to be melted, and likewise, the greater the difference between the Tg temperature of a material, compared to the temperature of the environment and the bed, the greater the chances of suffering from warping and/or cracking.
As an example, we can mention the two materials commonly used in 3D printing, the PLA that has an approximate Tg of 52°C (125°F), and the ABS that has an approximate Tg of 98°C (208°F).
And finally, Young’s modulus or longitudinal modulus of elasticity is a parameter that characterizes the elastic behavior of a material.
This parameter also influences how prone a material will be to suffer from warping and cracking. The higher Young’s modulus, the stiffer the material, conversely, materials with a lower Young’s modulus are more elastic, therefore, easier to bend under load.
As the most elastic material is less prone to warping and cracking, this is because the internal efforts caused by heat stress dissipate better in this type of material. As it is elastic, the upper layers are less likely to bend the lower layers.
This can be easily visualized in an elastic band.
Let’s do the following imaginative exercise. Suppose we tie an elastic band to any load (any object weighing 1Kg for example), when pulling the elastic band at one end (we exert tension) it will be less likely that we will be able to move the imaginary load than if we did the same but with a copper wire.
This occurs simply because the elastic band has a lower Young’s modulus, that is to say, it is a more elastic material. It will be necessary to pull much more the elastic band to be able to move the imaginary load.
Going back to 3D printing and filaments, we can see this with TPU (a flexible material), which despite being a material with a high CLTE, is counteracted by its low Young module, therefore, it is less likely to suffer from warping and cracking.
There are techniques used by users of 3D printers to prevent warping and cracking, which are based on using methods that improve the adhesion of the filament to the printing bed, and in turn, try to decrease thermal stress reducing the temperature difference between the molten filament, the temperature of the environment and the temperature of the bed.
One technique or another is chosen depending on the filament used, we will talk about this later.
What 3D Printing Filaments are the Most Likely to Suffer From Warping and Cracking
As we could see in the previous section, in summary, the probability that a material presents warping and cracking is directly related to the following three values:
- CLTE (Coefficient of Linear Thermal Expansion): It tells us how much a material could vary in size in proportion to changes in temperature. The higher the CLTE, the more prone the filament is to suffer warping and cracking.
- Tg (glass transition temperature): It tells us at what temperature a polymer decreases its density, hardness, rigidity and its percentage of elongation. The higher the Tg, the more prone the filament is to warping and cracking.
- Young’s module: It gives us an idea of the level of elasticity that a material has. The higher Young’s modulus value, the filament is stiffer, therefore the material is more prone to warping and cracking.
To give you a clearer idea of which filaments are most prone to warping and cracking, we have prepared a table that orders materials from lowest to highest based on their tendency to suffer from warping and cracking.
Warping and Cracking Occur on all 3D Printers?
No, this is due to the fact that in the market there are 3D printers with better features, which manage to lessen the effects of warping and cracking much better to the point of appearing almost non-existent.
This is possible since many of these 3D printers have heat beds capable of reaching higher temperatures, even the printing area is closed so that the ambient temperature in the 3D printing will be higher.
And there are even professional 3D printers that have internal heating systems, achieving that the air inside the printing area is at even higher temperatures.
This helps to reduce the temperature difference between the Tg of the material, the temperature of the bed, and the temperature of the environment, thus reducing thermal stress and improving adhesion to the heated bed.
There are two very important aspects that you should know:
- A heated bed at a temperature equal to or greater than the Tg of the material during the entire 3D printing is also counterproductive because the first layers will not be totally solid, therefore, the upper layers will cool down and cause contractions (or generating heat stress) will easily bend and peel off the layer that is attached to the bed surface.
The most advisable thing would be to 3D print the first layers at a temperature close to the Tg of the material, thus achieving maximum adhesion with low thermal stress, and then gradually cool the bed a little to get the first layers to solidify well enough (put the bed at a temperature somewhat lower than the Tg of the material) so that it is more difficult for the thermal stress caused by the upper layers to deform and peel off the layer adhered to the printing bed.
- Even if you can properly adhere the model to the bed, and it will not be deformed by warping or cracking. Still internally in the model, the thermal stress will be maintained, which causes the piece to be more susceptible to break when subjected to stress.
That is why it is highly advisable to practice thermal post-processing called annealing.
Which basically consists of applying heat to a 3D print progressively, at certain times up to a specific temperature, and then letting the piece cool gradually in a controlled manner.
Obviously, in 3D printers that have internal heating systems, this post-processing is not necessary, since the printer itself behaves like an oven, so thermal stress is dissipated by the printer itself.
Now I would like to show you three 3D printers, which I will order in the following way:
- The first will be a simpler 3D printer, capable of 3D printing on various materials, but since it is not closed it will be the most prone to the materials printed on it suffering warping and cracking.
- The second will be a 3D printer that has a boxed print area, which helps a lot to reduce warping and cracking.
- And the third one, a 3D printer that has a heating chamber.
1. Creality Ender 3 Pro
Printing volume: 220x220x250mm
2. QIDI TECH X-Plus
Printing volume: 270x200x200mm
3. Makerbot Method X
Printing volume: 190x190x196mm
How to Prevent or Decrease Warping and Cracking in 3D Printing
1. Use a heated bed
This is one of the most basic tips.
Most 3D printers already have heated beds, the important thing is to set it to the right temperature.
Filament manufacturers usually tell you at what temperature you should put the bed warm to prevent warping.
A piece of good advice is to put the heated bed at a temperature equal to or slightly higher than the Tg of the material, then cool the bed a little so that this first layer solidifies well (it is recommended in the subsequent layers to let the bed cool 10°C (50°F) or 15°C (59°F) below the Tg of the material).
2. Clean the bed properly
Although it seems very irrelevant advice, the truth is that it is not.
It is essential that the surface of the bed is clean so that the first layer can adhere well.
Grease or dirt prevents the first layer from sticking properly to the surface and therefore increases the risk of warping.
Many people often clean the bed with isopropyl or ethyl alcohol.
3. Check That the Z-Axis and the Bed of the 3D Printer are Well Calibrated
It is important to verify this since it will depend on it that the setting of the layer height of the first layer remains as it is adjusted in the slicer if not, the first layer could be very high (the nozzle would be very detached of the bed during the printing of the first layer).
This would lead to poor adherence to the bed surface and therefore increase the possibility of warping.
If you own the 3D printer Creality Ender 3, in this article we show how to calibrate the Z-Axis.
4. Disable the Layer Fan
The layer fan is not usually used to 3D print with materials prone to warping and cracking, rather having the fan activated in this type of material would aggravate the problem. So, disable it!
5. Calibrate the Height of the First Layer
The first layer is usually decisive, it depends on whether the remaining layers are good, even many users consider this layer the most important.
That is why it is necessary to configure this first layer properly so that it adheres in the best possible way to the bed surface.
For this to happen, it is essential to adjust the height that the nozzle will have with reference to the bed (the height of layer) during the 3D printing of the first layer.
A very separate first layer of the bed would cause poor adhesion to the surface, increasing the likelihood of the print being warped.
A layer height very close to the bed also has its consequences, for example, the piece changes dimensionally during the first layer, it would become larger (towards the X and Y axes) as it is squashed (the first layer).
Also, a very low layer height during the 3D printing of the first layer could cause extrusion problems.
But generally, on materials prone to warping, the first layer is printed at a lower layer height than the layer height that the remaining layers of the 3D print will have.
For example, for ABS you could use a layer height for the first layer that represents 80% of the layer height that will be used for the rest of the 3D print, i.e. if you set the 3D print to a layer height of 0.3mm, the first layer will be printed at 0.24mm, thus improving the adhesion of that first layer to the bed surface.
For more detailed information about the first layer, we recommend you the article The importance of the first layer in 3D printing
6. 3D Print Slowly
This is another technique that 3D printer users often apply when printing with materials prone to warping and cracking.
It basically consists of printing a little slower than you would with other materials that are not as prone to these problems.
The idea is to test different 3D printing speeds until you find a speed setting that reduces the predisposition of the filament to suffer from warping and cracking.
Usually, the speed is slowed down a bit and tested, so on, until the ideal configuration is found.
7. Use “Brim” or “Raft”
These are two tools or functions found in the slicers.
The Brim is a kind of strip or edge that creates the slicer around the object to be 3D printed to improve the adhesion of the piece to the bed.
The Raft is a kind of bed or raft that creates the slicer under the object to be printed to improve the adhesion of the piece to the bed.
Both tools or functions have the same objective, using one or the other is the user’s decision, there are people who have a preference for Brim and others for Raft.
8. Decrease the Infill in a 3D Model
If the part to be 3D printed will not be subjected to stress or efforts, it is convenient to use the least amount of Infill possible, since the higher the Infill there will be a greater amount of material contracting due to the change in temperature and thus generating greater thermal stress to the part, which translates as a greater possibility of suffering warping and cracking.
9. Using Materials that Improve the Adhesion of the Filament to the Bed
Next, we will give you materials or tools that help to adhere the filaments to the heatbed:
- PLA Filament: Painter’s tape, glue stick, glass plate, PEI sheet, hairspray.
- ABS Filament: Kapton tape.
- PETG Filament: Painter’s tape, glue stick, PEI sheet.
- TPU Filament: Painter’s tape, PEI sheet.
- Nylon Filament: Glue stick, PEI sheet.
- ASA Filament: Glue stick, PEI sheet
- PC Filament: Glue stick, PEI sheet, PC printing adhesive.
10. Use of Liquids to Improve Adhesion to the Heatbed
The best known and used is what is known as “ABS juice“, it is used to improve the adhesion of ABS to the heatbed. It consists of mixing pure acetone with ABS.
The ABS end up dissolving in the acetone and we obtain the famous “ABS juice”, which we distribute on the printing bed, to then start 3D printing.
As a disadvantage, it is sometimes difficult to detach the piece from the bed, and it is also usually more difficult to clean the bed after 3D printing.
There are other experiments by makers that have gone quite viral.
One of them is mixing water with sugar, this sticky mixture also helps to improve the adhesion of the pieces to the bed.
Another experiment is the use of gelatin or “Jello Solution”, it consists of mixing one (1) part of gelatin with ten (10) parts of water. The gelatin must be tasteless.
These other experiments are applied in the same way that the “ABS juice” is deposited on the bed evenly before starting to 3D print.
If you’ve experienced any of these techniques, let us know in the comments!
11. Designs with Rounded Edges and Apply Adhesive
Round surfaces are structurally better at withstanding thermal stress, which is why it helps prevent warping.
What is sought with this technique is to design 3D printed parts with rounded support bases, to which additionally we will put an adhesive tape during the printing to help the piece to stick on to the heatbed.
Once the 3D printing is finished, the adhesive tape is removed, the piece of the bed is peeled off, and the rounded supports created by us are cut.
12. Homemade Solutions to Avoid Warping & Cracking in 3D Printing
There are several modifications or fixes that you can change or add to your 3D printer that can help prevent warping and cracking and I would like to tell you about 3 specific modifications.
1. Close Your 3D Printer
This first modification consists of enclosing your 3D printer, of course this is only applicable if your 3D printer comes open by factory.
Enclosing the 3D printer helps keep the heat inside and therefore the air will be warmer, it will also prevent cold winds from affecting the 3D print.
All this leads to fewer temperature changes, which is equal to less thermal stress and fewer probabilities of producing warping and cracking.
2. Placing Cork Under the Printing Bed
There are 3D printers that find it difficult for the heatbed to reach higher temperatures.
This is most appreciated in places where the ambient temperature is colder.
It means that maybe your 3D printer is theoretically designed to be able to reach a temperature of 100°C (212°F) in the heatbed, but due to climatic effects, your 3D printer either fails to reach that temperature or takes a long time to reach it.
One way to improve this is to place cork sheets under the heatbed, the cork is a good thermal insulator, so the heat energy generated by the heat bed would not dissipate as much from the bottom of the bed, this is really convenient to avoid the lower part of the bed to exchange heat with the environment.
This solution helps the heatbed reach the temperature for which it was designed faster, and sometimes even achieves slightly higher temperatures.
This obviously helps to set the bed temperature appropriately in order to prevent warping and cracking.
3. Put Light Bulbs that Generate Heat in your 3D Printer
This last modification consists of placing inside the printing area light bulbs that help generate heat inside the 3D printer.
Apart from this, you will also have the advantage of having better lighting.
Why generate more heat inside the 3D printer with light bulbs? Well, you will be able to keep the air temperature inside the printer warmer, and we already explained how convenient this can be for 3D printing by FDM.
4. 3D Printer Leveling Sensors
Leveling sensors help with bed leveling, although leveling the bed is a job that can be done manually, leveling sensors improve and simplify this task.
By having a leveling sensor, there is a more precise leveling, which means that the first layer prints with the exact layer height that we set in the slicer, which implies better adhesion and a lower probability of suffering from warping during 3D printing.
Get it on Amazon:
5. Use a Heating Chamber
We have already talked about the advantages of having a heating chamber, either you build your own (which is certainly laborious), or buy a 3D printer that incorporates one (which we know is expensive).
The reality is that a heating chamber in conjunction with a heatbed are usually the best combination to prevent warping, cracking and even minimize thermal stress on 3D printed parts.
Conclusions About Warping and Cracking in 3D Printing
Warping and cracking are quite frequent problems, there are materials that are more predisposed to suffer from these effects.
This is directly related to the following values:
- CLTE (linear coefficient of thermal expansion)
- Tg (glass transition temperature)
- Young’s modulus.
The higher these values, the more prone the material will be to warping and/or cracking.
There are various methods to combat these effects, ranging from adjusting 3D printing parameters, 3D printer modifications, to acquiring professional 3D printers specialized in printing with filaments prone to warping and cracking.
If you ask yourself, why do I want to 3D print with these materials? The answer is that these filaments tend to have better thermal and mechanical properties.
There are also filament manufacturers who have taken it upon themselves to modify printing materials to make them easier to print in FDM.
For example, composite materials with carbon fiber or fiberglass are usually less prone to these deformations, since the reinforcing material (carbon fiber or fiberglass) has lower CLTE, which provides dimensional stability to the base material (PLA, ABS, PETG, TPU, Nylon, ASA, PC).
As a disadvantage, to 3D print with these types of filaments (composite with carbon fiber or fiberglass), it is necessary to use abrasion-resistant nozzles (usually stainless-steel nozzles).
Another example of materials modified to make them easier to print by FDM is PolyMide CoPA filament.
It is made of Nylon and was designed so that you are not so prone to warping.
Obviously, it has its disadvantages compared to other Nylon. For example, the PolyMide CoPA has a Tg of 67°C (152°F), a normal Nylon usually has a Tg of approximately 88°C (190°F), that is, the PolyMide CoPA is less resistant to temperature.
In conclusion, the way to control warping and cracking is based on improving the adhesion of the first layer to the printing bed, and in turn, it is necessary to control the thermal stress caused by temperature changes.
Remember that it is possible to avoid warping by improving adhesion to the bed, but that does not imply that you would be eliminating the internal thermal stress of the 3D printed part, therefore, it is possible that it will fracture more easily when subjected to stress.
To reduce thermal stress if you do not print with a 3D printer that has a heating chamber, it is advisable to subsequently apply an anneal to the 3D printed part to eliminate thermal stress.
See you soon Machine Bros!