Why do my printed 3D models have layers that crack or break?

3D printed models are built by printing layer by layer. If the two layers do not adhere well to each other, it may result in cracking or breaking. Here comes an introduction to the causes and solutions for layer cracking or disconnection.

1.The layer height is too high - Reduce the layer height in the slicing software

Most 3D printer nozzles are between 0.3 and 0.5mm in diameter, and filaments are extruded from this very small hole to form very fine draws, which in turn build detailed prints. However, these small nozzles, also lead to layer height limitations, and when you print another layer on one layer, you need to make sure that the new layer is extruded onto the layer below so that the two layers can be bonded together.

In general, you need to make sure you choose a layer height that is 20% smaller than the nozzle diameter. For example, if your nozzle diameter is 0.4mm, you should use a layer height of no more than 0.32mm, otherwise the plastic on each layer cannot bond properly to the layer below it. Proper layer height should be ranging from 0.1-0.24 mm (we usually set it between 0.1-0.2 mm). In this way, the printed model will be smooth with good adhesion between layers. So, if you find that the printed parts cracked, layers fail to adhere well, you need to check whether the layer height and nozzle diameter is matched. If not, try to reduce the layer height to see if you can make the layer bonded better.

2.The printing temperature is too low - 1) Turn up the temperature via software 2) Adjust higher temperature when printing

Compared to the cold plastic, hot plastic can bond together better. If you find that the layers cannot be well bonded to each other, and the layer height is set properly, then it may be that your wire needs to be printed at a higher temperature. For example, to print ABS plastic at 190 degrees Celsius, you may find that the layers fail to bond well. This is because ABS generally needs to print at 220 to 260 degrees Celsius. Therefore, it’s helpful to confirm that you are using the correct print temperature for the filaments. You are suggested to try increasing the temperature by 10 degrees Celsius at a time to see if there is any improvement.

Ender-PLA printing temperature: 190-210°C

CR-ABS printing temperature: 220-260°C

CR-PETG printing temperature: 230-250°C

CR-TPU printing temperature: 210-240℃

CR-Silk printing temperature: 190-230℃

CR-Wood printing temperature: 190-230℃

3.The printing speed is too fast and the wall thickness is too thin - Adjust the printing speed and wall thickness through the slicing software

Try to think about printing a model at 100mm/s and 50mm/s, the effects of their layer adhesion are different. Wall thickness is at the same principle. Comparing the wall thickness of 0.4 mm with 1.2 mm, 0.4 mm is easy to crack, but 1.2 mm is more steady. In winter, wall thickness which is too thin will lead to layer split easily. (Note: Proper printing speed with proper wall thickness and filling can be more effective to avoid the model layer split.)