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Possible printing substrate issues on the HP Latex R Printer Series

HP-Sonia 21st of August 2018

There are physical marks on the substrate

This only can occur when substrates sensitive to permanent deformation are used. These marks are usually seen in isolated areas and mainly caused by high curing temperature or substrate tensions.

Here are some suggested ways to correct the problem:

1. Check that the substrate you are using is the same type as the one you have selected in the Internal Print Server.

2. Check that there are no defects at the substrate edges.

3. Check that you are using the generic substrate preset for the substrate category. The use of incorrect values could cause incorrect substrate behavior.

4. Flexible substrate only: Reload the substrate and try to minimize skew while loading. Check that you are loading the substrate using the correct procedure.

5. Try to reduce curing temperature and ink quantity if possible, and raise the curing airflow airflow to help in reducing the substrate deformation.

Rigid substrate too close to the carriage bottom
If a rigid substrate is too close to the bottom of the carriage, the crash sensor cancels the job.

● Ensure that the substrate thickness is entered correctly in the Internal Print Server.
● Ensure that the substrate lies flat on the substrate-advance belt while printing. In particular, check that the substrate is not deformed.
● Ensure that the substrate you are using is the substrate selected in the Internal Print Server.
● Ensure that the substrate edges have no defects.

A spindle latch suddenly opens during flexible substrate printing
If a spindle latch is not closed before starting the substrate load, or it is opened by someone after the spindle was already moving or while the substrate was under tension, the spindle can move out of place. Closing the latch in those conditions can cause an incomplete latch engagement, and then at some point the latch may spontaneously open completely.
The best solution is to eliminate substrate tension, avoid spindle movement, and then close the latch properly. To do this, return to the substrate load/unload menu, ensure that the spindle is properly in place (in case of doubt, extract it a bit and then push it back fully inside again), then close the latch (the blue part should now go down completely).

The substrate advances with a loud continuous sound of vibration
A loud continuous sound of vibration during the substrate advance can be caused in the following ways:
● The input spindle is not applying tension.
● Wrong tension or vacuum settings result in an incorrect balance of forces on the main roller.
If you hear this sound, here are some suggestions:
1. Check that the substrate you are using is the same as the one you have selected in the Internal Print Server.
2. Check that you are using the generic substrate presets for the category. The use of incorrect values may result in incorrect substrate behavior.


NOTE: Only substrates with high friction along the substrate-advance belt or substrates that easily wrinkle with temperature need high output tension values. Check that your output tension is recommended for your substrate.


3. Check that there is no telescoping of the input roll.
4. Reload the substrate and try to minimize skew while loading. Check that you using the correct loading procedure.
5. Increase the input tension in steps of +5 N/m from the recommended setting for each category until you eliminate the issue.

There is skew or telescoping on the output spindle
Extreme skew (approximately 10 mm peak to peak) and telescoping in the output spindle while it winds can be caused in three main ways:
● The substrate has not been correctly loaded and aligned during the loading procedure.
● The roll loaded on the input spindle is skewed, and this skew is transferred to the output spindle.
● The roll loaded on the input spindle has been wound with different tensions at its two ends.
Printing on rolls that are not wound accurately during manufacturing may lead to wrinkles and skew
problems and, generally, this problem can be identified easily because you can see a loss of tension at one side of the substrate between the input roll and the main roller.

TIP: When suffering from extreme skew that tends to increase (normally with highly temperature-sensitive substrates), try to use a thicker core that is not deformed by the rubber traction grooves on the spindle when inflated. Then follow the guidelines below for reducing skew.

Generally, the main contributor to skew is an imprecise substrate load, and the effects of that are worse with wide rolls. However, if you have some skew or telescoping but this does not affect your print quality, and does not generate wrinkles in the substrate, there is no need to take any action.

IMPORTANT: HP recommends using the automatic de-skew process in all roll loads.

There are wrinkles and ink smears on the substrate
Wrinkles in the substrate indicate that the substrate settings that control the substrate shape are not optimized.
This can cause various printing defects:
● Colored bands in area fills in the vicinity of the wrinkles
● Ink smears if the printhead touches the substrate
● Cockle
● A substrate crash if the printhead's movement over the substrate is impeded 

There are various reasons why wrinkles and other consequent effects could appear while printing:
● Incorrect loading of the substrate
● Incorrectly positioned edge holders
● Drying and curing temperatures too high for the substrate
● Differential expansion of the substrate due to variations in temperature
● Insufficient tension settings
● Non-uniform tension across the substrate when loading
● The roll loaded on the input spindle has been wound with different tensions at its two ends.

NOTE: When printing with rolls that have not been precisely wound with the same tension along their width during manufacturing, you may notice that, while printing, one of the sides of the substrate between the input spindle and the main roller loses all tension. This may cause wrinkles on the substrate-advance belt or telescoping on the output spindle.

If your prints suffer from any of the defects caused by wrinkles, here are some suggestions:
1. Check that the substrate you are using is the same type as the one you have selected in the Internal Print Server.
2. Check that you are using the generic substrate preset for the substrate category. The use of incorrect values may cause incorrect substrate behavior.
3. Check that there is no telescoping of the input roll.
4. Reload the substrate and use the automatic de-skew process. Check that you are loading the substrate using the correct procedure.

5. If you have experienced a substrate crash because the lateral edge of the substrate in the print zone is not flat enough, and is raised or even partially cut because you are not using edge holders, then you are recommended to use them.

NOTE: If you are already using edge holders, check that they are correctly positioned.

6. Try reducing the drying power and curing temperature.
7. Try reducing the curing temperature and ink quantity, and raise the curing airflow to help in reducing the substrate’s thermal contraction.
8. If you cannot get rid of the wrinkles, try raising the carriage beam slightly, so that the printhead is not so close to the substrate

There are ink marks on the substrate
This problem can occur if any component in contact with the substrate is dirty. Check the substrate-advance belt, pinchwheels, and curing module plates, and clean them if necessary.
If the ink marks occur at the sides of the substrate and not in the center, and you are using the substrate edge holders, check that they are correctly placed and clean.

There are drops of ink on the substrate


NOTE: In the above example, the distance between the drops is about 1 cm (0.4 in).

1. If you are using the substrate edge holders, clean them.
2. Clean the sides of the printheads and the sides of the printhead slots.
3. Clean the electrical connections to the printheads

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