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Common-Sense Solvent Printer Maintenance
As a service company, we love when you call us for printer service. It is an opportunity to help you in a moment of need, but too often the needs we see are a crisis that shouldn’t have happened. I personally find it 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 the cosmetics, where people put solvent-soaked cloths and splash ink all over their printer, but also even 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 between oil changes and wait until it breaks, or do you change your oil at regular intervals? I think we know the answer to those questions! I will use occasional automotive references in this article to try to keep things simple. Since pretty much anyone reading this has a car or truck, that concept should make things pretty easy to follow.
The good news is, maybe you can’t perform the full preventive maintenance program your printer may need, 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 the solvents, the ongoing maintenance is even more critical than your car, for which most systems are sealed (think your cooling system, oil, gasoline, etc). In the case of your printer, you have printheads and caps/capping stations/maintenance stations that are exposed to air when printing, and either 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. We will call these caps for the rest of this article regardless of the printer brand you may have.
Though each printer has its own maintenance routine, there are a number of things that apply to pretty much any printer out there, whether by Mimaki, Mutoh, HP, Roland, or other manufacturer. Let’s consider the technology and what is going on in your printer, working from the waste bottle back through the system.
The waste bottle is the end of the line and where the waste ink goes when you do head cleanings, nozzle washes, priming of printheads, or whatever these functions are called on your unit. If the waste bottle is too full, or if the service line is gummed up which feeds into it, your printer can get a bit constipated, to borrow from another analogy. No, I won’t go deep into that one. Your printer has a pump that pulls ink through the printhead and pushes it into the waste bottle. Help make the pump’s life a little easier! More on this later.
Most of the printers mentioned have a pull-through pump system that draws ink through the printhead 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 comes up to seal the connection between itself and the cap. A couple of thoughts here:
• If you don’t have a good seal, there can be air leaks 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, and in cleaning cycles, it won’t clean either. Either is bad news, of course. Several things can cause a cap-to-printhead seal issue:
• Old and worn out caps. These are rubber, and they will over time deteriorate with the constant exposure to solvents and heat over time. Solution – replace the caps.
• Poor alignment of caps and printheads. This is easy – if the caps don’t seal the printhead in the correct position, you will have air leaks. Solution – have a capping station alignment performed. Replacement of caps and alignment are a part of all the PM’s we perform.
• Problem with capping station motor – though the specifics may vary from model to model, some employ motors/belts to raise or lower the caps during/after printing. Solution – repair/replace the motor assembly or affected parts.
• This is where you come in – 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 of the caps. 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. Solution – take swabs and maintenance solution and gently swab the caps – regularly. Yes, I know, you want to go home, but you will love your printer more if you do this at the end of a long printing day and it can do a better job of self-maintenance overnight.
• No matter how good you are in keeping the caps clean, there will still be an accumulation of pigment in the cap itself and down below. Use a recommended maintenance solution to wash the caps, sufficient in quantity to run right down to the waste bottle. This will thin out the accumulation and help avoid the “constipation” of waste ink getting to your waste bottle.
Hopefully this is all starting to make sense to you!
Another crucial component of your ink system is the wiper/wiping station. On most printers, this is typically a rubber blade that wipes across your printheads periodically during printing. Using what you now know about your 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 particulate 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 effect on your print quality too.
A few more thoughts (yes, you thought I was done with you – not so soon!):
• Keep the ink flowing and the printheads “wet.” Workload varies from shop to shop, and even busy shops may have their down days where they don’t print to much or at all. Even if you don’t print for a while (a few days or more), continue your daily maintenance, and run a set of color bars equal to your inkset each day. If CMYK, do about 4 – 6” x 12” (15.25 x 30.5 cm) blocks of 100% of each color. If you have light cyan and magenta, make it 6 – 6” x 8” (15.25 x 20.3 cm) blocks with the light colors being only 40% density to assure that ink color is being used by the RIP. Same goes for orange, green, or white ink. See below for an example. This will force your printer to use these colors even if you are not printing at the time. Scale according to the width of your printer and material, of course.
Some printers even have a thin “confidence stripe” automatically print on the edge of the graphic to assure that all colors are being used all the time. I have seen graphics where printheads that have not been used for a while (say a pure red graphic for 6’ (1.83 m) that starts using black again) – it takes a while for the black to get going again with the result being a ruined print. TRADE SECRETS! – If you think you might have this problem or have had it before, and your printer or RIP does not have this feature, create your own confidence stripe around ½” (12.7 mm) wide with all 4-6 colors and run it the length of the graphic. Printing the full width bars as described above is also a neat trick to help unclog otherwise serviceable printheads that may have a few clogged nozzles.
• When they come up, don’t ignore the error messages and PM (preventive maintenance) flags that the manufacturers have put in your printer. We get calls all the time from people asking how to bypass them. The manufacturers have put them in your printer for a reason, and like an oil change, they should not be skipped or waited on for too long. Stretch a little, OK. 3500 miles is not going to kill your engine if you regularly change your oil at 3000 mile intervals. 6000 or 7000 – your engine simply won’t last as long as it would with more frequent service intervals.
• If you plan not to use your printer for a while, say for longer than a month or more, we suggest that you have your system flushed. There are right and wrong ways to flush a printer, so don’t hesitate to call us for help. Additionally, there are specific storage fluids which are not as volatile as maintenance solvents, so they won’t dry out as quickly and your printer will be protected longer.
Let’s talk about your ink for a moment. All printers start with original equipment manufacturer (OEM) ink which of course is recommended by the manufacturer. Of course it makes them money, but there is a good reason it is required to maintain your warranty out of the gate. Their inks are formulated with the proper chemistry, viscosity, volatility, and even pigment particle size to properly flow through the ink system and printheads. Think about it, there is a lot 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 you 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 takeup system and they will be ruined. Even the temperature settings with the pre-, print-, and post-heaters come into play here. This is not to say that there are not a number of good options for alternative ink out there. There are, but not all ink is created equal. A discussion on ink is an article all to itself.
We have covered your ink system pretty thoroughly, so let’s cover 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. I cannot make a specific suggestion here as this varies by make and model. Periodically perform a gentle cleaning on you encoder strip with isopropyl alcohol, or a soap and water mix with a just a bit of soap, 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 please consult your owner’s manual to be sure.
So we have covered maintenance on the money making part of your printer, so let’s talk for a minute about keeping it good looking 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 go 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” to some real ugly messes. Generally, the “proverbial ones” have better and more consistent results and longer intervals between major service. Though we recommend PM intervals of 12-18 months, we hear of some people going 3-4 years or more before service is required.
I chuckled to myself as I wrote this article thinking I could put myself out of business if everyone followed these simple steps. The reality is, that won’t happen, and there will always be a need for what we do. Bottom line – if you take care of your printer, it will take care of you, and last longer as a result. Give yourself your best chance at success here. Sometimes with even the best and most fastidious care your printer will break down, just like your car. When that happens , we are ready to help, just call us.
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