3D printing involves creating a model one layer at a time. The structural integrity of the final print depends upon one layer of the material adhering onto the previous layer successfully. If the newly added layer does not bond to the bottom layer, the final print will be susceptible to cracks or breaks. This post finds out the causes of and ways to prevent layer separation in 3D printing.
What is Layer Separation?
Layer delamination refers to the action of adjusting the 3D printed layers so that they stick firmly together. This is a step taken towards preventing cracks and improves the sturdiness of the final print. It is not a complicated process, but it involves a few adjustments to your printer and slicer.
The easy tricks to prevent layer separation in 3D printing
1. Adjust Printing Temperature
The first step towards preventing 3D print layer separation is to increase your printer’s extruder temperature. The layers adhere to each other by fusion at high temperatures. If the extruder temperature is cold, the material coming out of the nozzle will not be hot enough to stick to the previous layer. That leads to layer separation on the final 3D print.
The process of increasing the extruder temperature should be done stepwise. Start at the average temperature and proceed to raise it at intervals of 5 °C until you notice changes in adhesion of the printed layers. Because each filament has its ideal temperature, this testing process will help you find the best printing temperature for your model.
The warmer the filament gets, the better it bonds. Printing at a lower temperature the material will shrink and separate from the layer below. However, it would be best if you didn’t get the temperature too hot. Start dialing down the temperature if you notice over-extrusion in the prints. To increase or decrease temperatures navigate to the Temperature tab in the Edit Process settings. Increase or reduce by intervals of 5 degrees as you monitor changes.
2. Adjust Print Cooling
The other reason why your 3D print separates could be the fact that your cooling fan is overworking. Reducing the fan speed has the same effect as increasing the extruder temperature. It enables the extruded material to remain hot enough to stick to the previous layer. If adjusting the print temperature doesn’t produce the desired effects, you can decrease the fan speed to try to solve the 3d print layer adhesion problem.
For proper bonding between the layers in a 3d print, the materials leaving the nozzle need to be at its melting point. It is difficult to achieve this if the fan is blowing cold air at top speed. The cooling will happen too fast, and the thermoplastics will transform from a liquid state to a glass state stopping all further bonding processes.
Consequently, in order to achieve strong bonds between the print layers, you will need to decrease your fan speed to allow the fresh layer to stay hot enough to melt the plastic layer below it. That enables the polymer chains to entangle in an unbreakable bond.
3. Adjust Extrusion Flow Rate
If there is too little filament flowing out the 3D printed parts will have gaps between layers. That often leads to 3D print layer adhesion problem that causes the deterioration of design quality and sturdiness of the final print. Your prints WILL be susceptible to warping and breakdown.
By increasing the printer’s flow rate, you allow for the more molten filament to flow out of the nozzle. The more the thread that flows out of the nozzle, the better chances it has of sticking. 3D printing is like applying tape to a surface. You have to press it down for it to adhere.
You can achieve that kind of layer compression by increasing the flow rate so that the fresh layer presses hard on the previous one.
Increasing the print flow rate helps to achieve strong bonds between layers. The process should be gradual, increasing the rate at increment intervals of 5 %. In case you notice over-extrusion, reduce the flow rate a little until you get the optimum speed.
In case after increasing the extruder temperature and reducing fan speed you find the 3D print layers are still not sticking, you can be confident the printing rate of your nozzle needs to be set to maximum.
4. Use Correct Nozzle Size
The standard 3D printer nozzle diameter is between 0.2 and 0.6mm. Thermoplastics extrude from this tiny hole in the form of a finely squeezed thread to build larger printouts with refined details. Nevertheless, these smaller nozzles often limit the layer heights.
During the printing process, you will need to ensure that the fresh layer is pressed onto the previous layer for secure bonding. For that to happen, the layer height has to be 20 % smaller than the nozzle diameter. With bigger nozzles, you can print thicker layers that improve the chances of a firmer adhesion. However, using a big nozzle will also demand a higher printing temperature and a faster flow rate.
5. Adjust Printing Speed
High print speeds could cause the 3D print layer adhesion problem. In the extrusion process, you will have to make sure that the thermoplastic can adequately adhere to the previous layer before following with subsequent layers. If the layers print too fast the material will not have a bond with the previous layers. In light of that, it is advisable to adjust the print speed to allow the new layers to bond on the first layers.
To adjust the print speed, navigate to the Edit Process Settings and select the Layer tab then Layer Speed. If your printer is printing too fast try reducing this speed at intervals of 10mm/sec.
6. Clean Clogged Extruder
Clogging in the extruder is noticeable by signs such as under extrusion. To find out whether your printer nozzle is blocked, remove the extruder lever and try pushing the filament through by hand. If it is hard to pass through the nozzle or doesn’t come out at all, the nose could be clogged.
Clogged nozzles happen because of many reasons among them dust particles or dirty filament forming a plug, nozzle height too close to the print platform or the extruder temperature set too hot. Clogging can also happen when you leave the printer idle with a heated nozzle, or when you have taken too long to clean the nozzle.
To clean the nozzle, try brushing with a brass wire brush. That can help to clean off all debris on the surface. Also, get the printer warmed up and insert a hypodermic or acupuncture needle through the nozzle to unclog the blockage.
Another effective way to clean your nozzle is cold pulling with a nylon filament. That involves yanking the filament through a cooled nozzle to clear the passageway. Alternatively, you could clean the clogged vent by detaching it from the printer and washing it in a bath of acetone chemicals to dissolve the hardened filament. You can then use a blow torch or heat gun to melt and flush out the clogged bits.
7. Adjust the Z-Axis
Having a layer height that is in sync with the nozzle diameter allows the fresh layer to bond cohesively with the layer below it. That improves the dimensional accuracy of the final print and ensures that the adhesion is firm enough. If you see some cracking or breaking between layers in spite of all corrective measures, you can adjust the layer height by jogging the Z axis of your printer.
The 3D printer’s Z axis facilitates the printer’s operation, adding depth and design to the final print. If there were only X and Y-axes, the final copy would have a flat design and wouldn’t be three dimensional. The Z axis in your print is responsible for the vertical up and down movement of the nozzle assembly.
If the Z-axis rods are disproportionate to the X and Y axis rods, you will likely get a 3D layer separation or a crack on one side of either the X or Y axis of your final print. This problem is often more pronounced when printing tall structures.
To rectify this layer adhesion problem, start by powering the printer and return all the axes to their home position. Adjust the Z-axis rode 5 mm upwards and release the stepper motors. Gently move the extruder assembly such that it is at the center line of the build platform. After that, adjust the build platform so that it sits directly below the nozzle.
Next, place a thin business card on the build platform, under the nozzle. Adjust the Z-axis downwards at intervals of 1mm steps until the nozzle is within 1mm of the card. Move the Z-axis by intervals of 0.1mm until the nozzle contacts the thin card such that the card cannot move freely under it. Use this new nozzle height (minus 0.002 the height of the flat card) as your new Z offset setting.
One of the most significant 3D printing defects is 3D print layer separation. Even with great designs and top-shelf printers, you cannot be immune to this problem. Use the above layer adhesion enhancement tricks to enjoy all the possibilities and conveniences of your 3D printer. You will be able to get stellar and sturdier results with your final prints.