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OCTOBER 2012





Common Sense Maintenance For
Solvent-Based Inkjet Printers
a reprint from SGIA Journal May/June 2012 Page 53

As a service company, we love when we get calls for printer service. It's an opportunity to help in a moment of need, but too often the needs we see are a crises that shouldn't have happened. It's amazing that people often spend more for a piece of equipment that makes them money than they spend on their car, which costs them money, but they will take far better care of their car. Not only does this apply to cosmetics, where people put solvent-soaked cloths and splash ink all over their printer, but more importantly, the mechanics, which are the heart and soul of the printer.

Would you place a solvent-soaked cloth on top of your car's finish? Do you drive your car 20,000 miles between oil changes and wait until it breaks, or do you change your oil at regular intervals?

The good news is, maybe you can't perform the full preventive maintenance program your printer needs, but you can do your own "oil changes," or at least perform basic maintenance between major service intervals, often stretching that service interval out further. Like your car, your printer has critical fluid systems. In virtually any mechanical device, the fluid systems need to be kept clean for optimum life and performance.

Your printer is no different. In fact, due to the volatility of solvents, ongoing maintenance is even more critical than for your car, for which most systems are scaled (e.g., your cooling system, oil, gasoline, etc.)

In the case of your printer, there are printheads and caps/capping maintenance stations that are exposed to air when printing, and may be left exposed and in danger of drying out if there is a mechanical or electrical failure, or if poorly seated/sealed when in a resting position.

Though each printer has its own maintenance routine, there are a number of things that apply to much any printer, regardless of manufacturer. Let's consider the technology and what is going on in the printer, working from the waste bottle back through the system.

Ink Maintenance
The waste bottle is the end of the line, where the wasted ink goes after you clean the printheads, wash the nozzles, prime the printheads, or whatever these functions are called on your unit. If the waste bottle is too full, or if the service line which feeds into it, is gummed up, the printer can get a bit clogged. Printers have a pump that pulls ink through the printhead, and pushes it into the waste bottle.

Most of the printers mentioned have a pull-through pump system that draws ink through the primhead and helps prime it to keep ink flowing. In order to effectively draw ink through the printhead, there has to be a good seal between the cap and the printhead. Typically, the printhead has a flat surface, and the cap is essentially a rubber boot that seals the connection.

If you don't have a good seal, air leaks may occur when the pump tries to pull ink through the printhead. When this happens, no ink will pull through the head, and it won't prime. In cleaning cycles, it won't clean either. Either one is bad news, of course. Several things can cause a cap/ printhead seal issue:

  • Old and worn out caps. These are rubber and they will deteriorate over time with the constant exposure to solvents and heat over time. The solution is to replace the caps.
  • Poor alignment of caps and printheads. If the caps don't seal the printhead in the correct position, you will have air leaks. The solution is to have a capping station alignment performed.
  • Problem with capping station motor. Although the specifics may vary from model to model, some employ motors/ belts to raise or lower the caps during/ after printing. The solution is to repair/replace the motor assembly or affected parts. Poor maintenance of the caps can result in crusting of dried ink and pigments right where they need to seal - cap to printhead.

Additionally, failure to keep the caps clean will result in faster degradation. Even when you finally clean with solvent and swabs, the crust becomes abrasive and tugs off bits of the cap in the process, resulting in premature failure. The solution is to take swabs and maintenance solution, and gently swab the caps - regularly.

No matter how good you are at keeping the caps clean, there will still be an accumulation of pigment in the cap itself find down below. Use a recommended maintenance solution to wash the caps, sufficient in quantity to run right down lo the waste bottle. This will thin the accumulation and help avoid the "clogging" of waste ink.

Another crucial component of your ink system is the wiper/wiping station. On most printers, this is typically a rubber blade that wipes across the printheads periodically during printing. Using what you now know about your own ink system, what do you think will happen if you allow your wipers to be crusted with dry ink?

The crust can be transferred to your printheads, and dried particles of ink pigments can be pressed into the orifices in your printheads - with disastrous results. Use the same care you do with your caps. No, these are not "seal" critical as are the caps, but less efficient wiping can have great effects on your print quality too.

Manufacturer Inks
All printers start with original equipment manufacturer (OEM) ink, which is recommended. Of course it makes them money, but there is good reason it is required to maintain your warranty out of the gate. The

manufacturer's ink is formulated with the proper chemistry, viscosity, volatility and even pigment particle size to properly How through the ink system and printheads.

There is a lor of physics and chemistry going on here - you have flow of ink from cartridges or tanks through ink lines, through dampers, which generally have filters in them, and then have to be jetted out of

microscopic orifices at precisely the right size, moment and direction to get a clean print. If the ink dries too fast, it may coagulate on the printhead during printing, or overnight while the printer sits. The ink may not spread enough when it hits the vinyl, and you may see print banding. If the particle size is too large or irregular, your printheads may clog. If the ink dries too slowly, your prints may not dry before they wind up on your take-up system and they will be ruined. Even the temperature settings with the pre-, print-, and post-heaters come into play. This is not to say that there are not a number of good options for alternative inks out there. There are, but not all ink is created equal. A discussion on ink is an article all to itself.

Covering the Mechanics
For the most part, there is less to do with the mechanics of your system as compared to the ink train. Keep the rail where the printhead carriage traverses back and forth free of contamination, and lubricate occasionally with the manufacturer's recommended lubricant. Periodically perform a gentle cleaning on your encoder strip with isopropyl alcohol, or a soap and water mix, as you would to wash your car. The encoder strip is generally a clear plastic "ruler." The printer counts the tic marks on it so it knows its position as it traverses across the material. Recommended maintenance details, materials and intervals vary, so consult your owner's manual to be sure.

In addition to the moneymaking part of your printer, it's important to keep it looking good, as well as productive. Don't put solvent-soaked cloths, syringes, pipettes, bottles, or other maintenance items on your printer. If plastic, it will melt, and if paint, it may mottle the paint. If you splash ink on your printer, wipe it off quickly! Don't use a blade across the heater platen on your printer. No different than your car, no one wants a scratched up or scarred printer, even a used one. If you decide to sell it someday, it will be worth more when you have given it proper care.

As we go out in the field, we see everything from the proverbial "you can eat off it" printer to some real ugly messes. Generally, the "proverbial ones" have better and more consistent results and longer intervals between major services.

Bob_FlipseA 20-plus year industry veteran, Bob Flipse was an early innovator in wide-format digital printing. Flipse is currently a partner at Grafx Network, a nationwide service company for wide-format printing equipment. Email: bob@grafxnetwork.com

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