Z layer separation, also called delamination, is the phenomena of having one or more layers in the Z axis not sticking correctly to the layer beneath it. This is often more visible near the corners and edges of the printed piece.
This issue is normally not related to the printer itself, but rather to the user-defined settings and elements.
While this problem can happen with any kind of filament, I have only experienced it with ABS. This is no coincidence, ABS is in fact the most prone to suffering delamination due to its tendency to warp.
Like many of the setbacks in 3D Printing, this can be avoided by understanding the problem and taking action to prevent it. This is usually not a machine-related issue but rather a user-settings related issue, meaning that the user can make adjustments and avoid the problem.
Some of the many reasons why the issue can happen:
Type of filament being used: as mentioned before, ABS is the most troublesome material to work with when it comes to delamintation. An easy way to walk away from delamination consists on just using a different polymer. Delamination in PLA is way less frequent, in fact I have never seen delamination happening in PLA during the print (personal experience). We have a wide selection of filaments in our catalog, check it out.
Low temperature: it is possible that the temperature is high enough to be extruded out of the nozzle but not high enough for the extruded filament to correctly stick to the previous layer. Try increasing the temperature in 5 or 10 degree increments and see if this affects the results in a positive way.
High speed: printers are becoming increasingly fast and precise, but the mechanical and chemical properties of the polymers do have some limitations. Sometimes it is better to err on the side of caution and go for a slower printing speed to ensure that the extruded filament has enough time to properly connect with the previous layer. Try some slower speed like 30mm/s and watch for the results.
Room temperature: let's keep in mind that the thermoplastics used in 3D printing are very sensitive to temperature. A 5 or 10 degree C difference in your extruder temperature is usually the difference between a perfect print and a failed print. This is true for the extruder temperature, the heated bed temperature AND the environment's temperature. By "room temperature" I mean the immediate surroundings of your printer: Is there an open window nearby? an air conditioner? a blowing fan? Anything that could be moving the air "around" the printed part can be causing a temperature difference between the layers of the print. Many 3D printer models have their own enclosure, however, it is always a good idea to keep the machine away from air currents. Try turning off the AC and closing some windows and doors to diminish some of the room's air flow.
Flow: the amount of filament being extruded is an important variable when it comes to sticking the layer together. If the walls of the print look "thin" or if you see small gaps in the Z layer then it is probably a good idea to use a higher "flow" value in your slicer software.
Layer height: the maximum recommended Z layer height is 70% of the nozzle width. For example, of your nozzle has a 0.4mm width then you should keep the layer height at 0.3mm or less. Make sure you are printing within the recommended values.
Be sure to check for all the possible causes I mentioned above. If you experience delamination it may be happening due to some of those reasons or a combination of many.
The best complement for a good 3D Printer is a user that took the time to understand the underlying principles that will let the machine achieve its potential.
3D Printing can be an exciting activity and there is a small learning curve, but whether if you are hobbyist or a professional, the rewards are well worth your while.
I hope you found this information useful and I invite you to take a look at our catalog. Have a great day.