In the second part of his guide to DTG print heads, Colin Marsh, managing director of Resolute DTG, discusses cleaning and maintenance
Simple cleaning procedures play a big part in the longevity and general health of your print heads, but you need to do more than just cleaning the print head itself.
Colin Marsh, managing director of Resolute DTG
The capping station, or maintenance station as it is sometimes referred to, is responsible for general cleaning, as well as providing the correct environment in which to store the print heads when they are not in use. A complex labyrinth of tubes, pumps, rubber seals and a wiping mechanism are usually combined into one unit. Some capping stations are designed to be a consumable part that is discarded and changed once it reaches the end of its lifespan, but other, more industrial maintenance stations, are designed to be serviceable, which means they will last for the lifetime of the printer, as long as they are properly cleaned and maintained.
How does a capping station work?
As water-based DTG ink is jetted during printing, some minute particles (satellite droplets) may not reach the substrate and will become airborne for a split second inside the printer. A DTG printer with good extraction and filters should capture most of this, helping to keep the inside of the printer clean, while also pulling the ink mist away from the print head. Inevitably, however, some particles will adhere to the surface of the print head; at this point the ink is still part water and easy to remove.
Throughout the working day, natural particle attraction occurs resulting in the minute droplets joining with others and growing in size. These can be seen as very small droplets on and around the print head. During general maintenance an automatic print head clean will remove these droplets whilst performing two different operations. Firstly, a quick sharp belt of suction is used to draw a small amount of ink through the nozzle exit holes quickly, dragging any waste droplets with it. This, in turn, cleans out the exit nozzle hole before the accumulated ink droplets start to set and take on the form of soft rubber.
Next, a physical wipe off the surface of the head leaves it clean and ready to print again, or be parked on the capping station. A rubber wiper blade or a fabric roller mechanism are the two most common methods that are used to perform this process. As the capping station cleans the head it becomes dirty, but a capping station can’t clean itself and relies on manual cleaning on a regular basis. Neglecting the capping station can cause your print head serious damage; in some cases it can clog beyond repair and require premature replacement.
The capping station requires manual cleaning on a regular basis
The blade is now clean and ready to print
Cleaning your print heads
In general, print heads are more robust than you would imagine, so the cleaning regime for most of them will be the same. Nevertheless, you should only use the cleaning fluids and consumables recommended by your DTG printer supplier. Purchasing different products – even if they appear the same – can cause irreparable damage to print heads and capping stations.
First, you should clean the surface of the print head and its surrounding areas, making sure any ink or fibres are removed with the correct cleaning swab and solution. Use only gentle motion and pressure, and always wash your hands first. If you’ve been printing during the day you will have pre-treatment residue on your hands which could kill your print heads in seconds should it be transferred during the cleaning process. Once the heads are clean, move onto the capping station. The rubber seals should be cleaned, and all ink residue removed. If your capping station has a rubber wiper blade make sure this is cleaned thoroughly. Next, drip a small amount of capping station flushing solution into the rubber seals and wait for it to drain away; this solution is designed to stop ink drying in the tubes overnight while the printer isn’t working.
Once you have finished your cleaning process it’s always best to initiate an automatic cleaning cycle performed by the printer itself to make sure no cleaning solution is left on the head and wiper blade. Last, but not least, always print a nozzle check to make sure your cleaning is complete. This ensures that none of the nozzles contain congealed ink, which stops the ink from jetting. This cleaning process should take only five minutes at the end of the day, but if you forget too many times, you’re putting your print head and capping station at risk of premature failure, which will incur a substantial cost.