HP S300, S500 User Manual

HP Stitch S300 and S500 Printers

TECHNICAL NEWSLETTERS FROM CUSTOMER ASSURANCE

Date: June 2020	Impact/Severity: Medium
Region: WW	Category/Area: Applications
Audience: Support	Confidentiality: HP Public

How to increase drying efficiency: Tips and tricks and external dryer recommendations

This document includes a list of recommendations for the proper printer settings to ensure that correct drying of print jobs is achieved. After following all these recommendations, if ink drying and transfer issues are still present, an alternative solution is presented that includes an external dryer.

Printer settings - tips and tricks

Before starting production, it is very important to find the optimal parameters for your paper/textile. Ensure that the number of passes, density, and machine settings are appropriate for your substrate and your final application.

If wrinkles occur when printing, this is an indication of excess ink; before you consider the purchase of an external dryer, try to use the tips described below to solve the issue.

1.1Optimize ink settings

The ink amount optimization is extremely important for several reasons. If we fire more ink than needed, we will waste ink and also make the printer operation much more difficult, increasing the difficulties in drying, winding the roll, etc.

Before starting production, most customers will print jobs at both 70% and 100% of ink (in the case of 1P, it will be between 50% to 80%), and then build a profile using both of the densities printed, and compare color saturation after calender:

•If the 30% ink step used shows the same step in saturation and there is a big visible difference, that means that 100% should be closer to the optimum. In that case the remaining ink left on the paper should not be much

•If, instead, there is no major visual difference between the two ink amounts printed, it means that the optimum ink amount is around 70%. If, however, 70% is not enough, then select 100% and reduce the global ink limit in the icc profile in steps big enough to see differences.

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Once saturation is matched with good transfer and little ink remaining on the paper, the optimum level is reached.

NOTE: If you need a level in between two levels of ink density, please refer to the guide on how to do it from the RIP.

IMPORTANT: Ensure that the heat fixation settings are the appropriate ones for your paper/fabric to give the optimal saturation.

1.2Optimize other printer settings

a. Drying temperature and airflow

Drying temperature and airflow are two parameters that have a direct impact on the drying capabilities of the printer.

Increase them when:

•The paper/fabric is not dry enough at the take up reel. b. Inter swath delay (ISD)

This parameter sets a delay of the carriage in milliseconds before starting the next swath, increasing the drying time of the previous swath. It is also used to increase the drying capabilities, but it has a negative impact on the total throughput.

Increase it when:

•Even with maximum temperature and airflow, the drying is not enough. c. Input tension

This is a parameter involved in the substrate control on the Print Zone input. It solves issues related with wrinkles or skew.

Increase it when:

•Having skew issues in the Print Zone. d. Output tension (S500)

This parameter allows the adjustment of the Output Winding performance. It also helps to control the flatness of fabrics in the Print Zone.

Decrease it when:

•Wrinkles are present in the Output Platen. This can also be solved by increasing the drying settings.

Tip:

•Thicker substrates usually need more tension and thinner ones less tension.

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e. Vacuum

The vacuum setting plays an important role in the control of papers in the Print Zone. Increase it when:

•There are smears due to substrate expansion caused by the ink, or there is curling of the substrate.

Decrease it when:

•There are vertical marks on the substrate coming from the Print Zone.

If, after following all these steps, you still have ink drying issues then consider the purchase of an external dryer.

External dryer solution

2.1Models tested

In some cases, an external dryer should be used to ensure that we are able to dry the substrate completely at the output area and, consequently, that a good-quality winding can be achieved.

The equipment tested is the external drying system for digital printing from NITE Industrial Co (KOREA). Specifically, the Self Standing Type SDSWT-1600 64” external dryer.

This is a 2.0 kW external dryer mounted with an aluminum stand (“built-in type” version also available).

It combines radiation and convection with (x2) fast-response medium-wave lamps and (x6) air fans.

	SDSWT-1600
Electrical power	2.0 kW
Drying technology	Radiation + Convection
Number of lamps	2 (covering the whole width)
Number of fans	6
Width	64”

http://www.nitemall.net/home/bbs/board.php?bo_table=pro03

NOTE: Internal validations have been done using this specific external dryer. However, it is also possible to use any other external dryer with similar or better characteristics.

The external dryer from FLEXA has also been tested. Specifically, the GHIBLI model. In this case, it is a 4.0 kW hotair dryer (convection) for 74” printers. It is known that hot-air technology (convection) is much less efficient than the radiation alternative described above.

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