PolyJet Part Quality Troubleshooting Guide

Stratasys Support Center – Part Quality Guide - Depressions

Depressions on the Model Surface

Sometimes, you may notice deformations that appear as depressions, or sunken-in areas, on the surface of the model . These depressions typically occur if the print heads are not jetting enough material, causing a lack of layer uniformity in certain areas of the model.

 

 

Possible Causes and Solutions

Clogged Nozzles

Sometimes nozzles can get partially or completely blocked, particularly if routine maintenance was not performed on a regular basis. This can result in depressions, grooves, and poor surface quality. If you also notice that any colors are consistently flawed or absent in your prints, that can be a good indication that clogged nozzles is the issue.

To conclusively determine if this is the cause, you can run the Pattern test to demonstrate the condition of all the nozzles in the print heads. This test is the basic verification of the printer’s ability to produce quality models. If nozzles are clogged, you will see missing stripes during this test.

Note: Each column has a tolerance of up to 10 consecutive nozzles before it can be considered a failed test.

Solution: If the Pattern test passes, move on to the next possible cause. If the Pattern test fails, run the Head Optimization Wizard. The wizard will indicate which heads, if any, need replacement. You can read the full guidelines for replacing print heads in the user guide

Preventive measures: To maintain the nozzles and prevent this issue from happening, clean the heads after every print job while print heads are still warm (~45 degrees Celsius). Also follow our other preventative maintenance best practices, such as regular inspection and cleaning of the orifice plates, cleaning the roller and wiper, and running the wizard. Refer to your user guide for details.

 

Clogged Material Filter or Tube

Clogged material tubes or filters can cause depressions because the correct amount of material does not flow from the tube or filter into the print head. If a head filling error appears, this may indicate that clogged material filter or tubes are the cause of the problem.

Solution: Contact your Stratasys service provider.

Preventive measures:None.

 

Internal Stress

Internal stress may cause depressions or sink marks. To avoid this, in the Tray Settings dialog box, select the check box Minimum pause between slices...

It is recommended to start by changing the delay time to  40 seconds. If it helps prevent sink marks, you can try reducing the delay time and checking the results.

TIP: In addition to the suggested above, you can also run the Dynamic Nozzle Test as a diagnostic tool if you suspect the nozzles are not working properly.


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