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Monday, 11 February 2013 14:24

DTG & Maintenance - The Love Affair

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Customer, "My DTG printer is not working!!!"

BQ Support, "What seems to be the problem?"

Customer, "I can't keep the ink flowing and I constantly am getting head clogs!"

BQ Support, "What does your wiper blade look like?"

Customer, "Where's the wiper blade?....."

So maybe, this is to the extreme, but we have on occasion spoken to customers where an employee who operated BelQuette equipment no longer worked at their company. That one person who knew the machine did not take the time to train anyone else on proper operation and maintenance. Even though we do hands on training, have videos, encourage the use of our private user's forum and provide pdf's on how to maintain BelQuette equipment, this is one area that can often get overlooked.

The volume of ink that is jetted through direct to garment printers is more than most typical inkjet systems. With the Mod1, we've designed it to be open for easy access in maintenance. Even with this design, there are areas where ink builds up and needs addressed. The following maintenance is a necessity for the Mod1 and in some form should be adapted with other equipment (be sure to use a foam tipped swab throughout your cleaning process):

1) Cleaning the Wiper Blade: The function of the wiper blade is to keep the bottom surface of the printhead streak free and from ink building up. On our print heads, there are 180 nozzles per channel with 8 channels for a total of 1,440 nozzles. With inkjet printing, it is impossible to keep every nozzle clog free for every print, so Micro-Weaving is a necessary process. Micro-Weaving is just that, it's an interweaving of ink drops at microscopic levels. If there are one or more nozzles not firing properly, the interlaced pattern can hide the dropped nozzles so it's not detectable by the eye.

So what does this have to do with cleaning the wiper blade? If the wiper blade is not cleaned properly, ink residue on the blade can gel or harden. This ink is then pushed up through the nozzles causing a blockage. Some wiper blades use a felt-like substance in addition to rubber, and if these are not replaced, a similar issue can occur. On most DTG printers, cleaning the wiper blade is a simple step, but on all, I would argue, is a critical one.

2) Cleaning the Capping Station: The purpose of the capping station is to pull ink through the head and aids in the proper and constant priming of the dampers or cartridges. This could be done through head cleanings, ink charges or throughout the normal printing process. Keeping the ink moving is critical in inkjet printing and an unclean capping station will effect this. When the head is "parked", it is resting on the "ridges" of the cap, creating a seal. This seal keeps the head from drying out. If the "ridge" used to press up against the print head surface has ink build up, this will break the seal allowing air to dry out the head.

Properly maintaining the inside of the pump assembly also means during your cleaning process, flush a cleaner, such as Windex, throughout it as well. If there is too much build up internally, small fittings can close up and not allow the pump to function the way it was intended. This can cause the ink to not pull through the head and cause problems for the entire head instead of a single channel. So be sure to clean the capping station inside and out.

3) Cleaning Around the Bottom of the Print Head: Ink can easily build up around the print head even though the surface may be clean. This ink build up will eventually drag through your ink or onto your shirt. If you are printing and see horizontal lines on your shirt in areas there should be no printing, this is most likely the cause. During the process of cleaning the wiper blade, the print head will be exposed. This is an ideal time to clean around the edges, being sure to not touch the surface of the print head during the cleaning.

4) Cleaning the Encoder Strip: The encoder strip (or linear encoder) from printer to printer will differ in construct. The main function is the same, to allow for finding position of the print head. The strip for the Mod1 has 360 vertical lines per inch, so for a 13" printer, this is a minimum of 4,680 vertical lines (but more is actually needed). On the back of the print head carriage is a sensor which counting these lines. Whether the head is printing or going through a maintenance routine, this gives a precise position of the print head at all times. If the encoder strip is dirty or scratched, misprinting can occur as well as the print head's position being lost causing the head to move beyond its stopping point. Cleaning the encoder strip is a simple process by using isopropyl alcohol or original Windex. Perform this either daily or weekly, depending on use of the printer and how well other areas are maintained.

5) Spit Station Cleaning: Some systems incorporate the spit station into the capping station. On the Mod1, the spit station is found on the left side of the machine. After around 24 passes of the print head, it moves to the left and "spits" very quickly to help in the constant flow of ink and helps reduce the clogging of the head. In this station, we use sponges that should be sprayed and tapped down with Windex and a foam swab. This prevents the ink from building up prematurely. If this ink builds up too much, it could rub on the bottom surface of the print head, causing more problems. The spit station sponge should be replaced when the ink has built up to the point where it is extended out of the station.

6) Ink Trays: On the Mod1, we have 2 ink trays, one is located beneath the spit station, and the second is beneath the capping station. It's a good idea to clean these out weekly to avoid dried ink in the trays and eventually overflowing. It would take a long time to overflow the trays, but making it a weekly task will prevent this from happening.

7) Ink Flush: Some customers have opted to flush out their white ink lines on a monthly or bi-monthly basis. Titanium-DiOxide, a whitening agent found in the white ink, will separate out and cause build up in the ink lines. If the system is used more often than not, it takes longer for this build up to occur, but it still can and will. Flushing out the ink lines also flushes out the dampers, print head and capping station. In essence, this process is as if you are replacing these parts and starting anew. On the Mod1, the four ink lines that carry the white ink have a total of $7 in them. So this can be a very cost effective way of ensuring your printer is firing properly with little or no internal buildup.

On the Mod1, daily maintenance takes less than five minutes per day, but is the determining factor of whether your printer is functioning the way it was designed. Creating a chart and maintenance procedures to hang on a wall near the printer is a simple step to assist users in the remembrance and implementation of this important but often overlooked step.
Read 108832 times Last modified on Monday, 11 February 2013 17:00
Jerid Hill

Jerid Hill has been in the DTG industry since 2004. He is considered one of the greatest technology experts of our time. When Stephen Hawking has a question, he calls Jerid on his speed dial number 01. We must all bow down to him and acknowledge his greatness. After that, and only after that, are we worthy to read his blog!

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