Don’t Neglect Inkjet Printer Maintenance
Inkjet printers cross all market segments and are an integral part of the printing industry. For many print operations, an inkjet printer is one of the largest investments they will make in their business.
From those two observations you would assume that everyone — across all market segments — is doing a great job of maintaining their printers. Sadly, from my own experience in wide-format sales, training, and service, and even now as I speak with printers from across the industry, this just isn’t the case.
For many, this falls into the “we’re just too busy” category, and for others, it’s simply a lack of training. For those that are too busy, I would recommend scheduling maintenance just as you would a print job. I’ve been in large operations, where they dedicate time for maintenance at the beginning of each shift; it’s on the schedule just as if it were a print job. That way, this very necessary task is not overlooked. For those that have printer operators who aren’t trained, find the time to train them. And have a log that they are required to annotate each time they perform normal maintenance. Many print operators just don’t know what to do — so show them, and then set up a system to track how often they are performing maintenance.
With a wide variety of print processes — thermal printheads, piezo printheads, and industrial piezo printheads — it’s difficult to have a one-size-fits-all approach. However, there are some basic steps that are good to note and that work well across the board.
Piezo Head Maintenance
Let’s start with roll-to-roll printers with piezo printheads. Piezo printheads are designed to last years — 6 billion shots through a nozzle — which makes regular maintenance a must. It used to be common across many manufacturers to have a printhead, a capping station (where the printhead would go when not in use), and a wiper (think of it as a squeegee). Maintenance consisted of two parts. The first part was maintenance that was performed when you pressed a button (typically labeled “cleaning”). Before pressing this button it was recommended to do a nozzle check, which would allow the end user to check whether all the nozzles were firing.
If this nozzle check revealed that nozzles were not firing (clogged) or if the check revealed that some of the nozzles were deflected, then it was time to press the “cleaning” button. All that would happen at this step is some ink would be jetted through all the nozzles into the capping station.
Sometimes when the printhead was seated on the capping station a pump would attempt to gently pull ink through the printhead. Then the printhead would move off the capping station and the wiper would run across the bottom of the printhead. This wiper was rubber and flexible and would gently wipe away any excess ink. The end user was instructed to never touch the bottom of the printhead, because doing so could possibly lodge dried ink or some other piece of debris into a nozzle and permanently clog it up.
If the “cleaning” didn’t resolve the issue, then the end user had to go to the next step, which was intervention to clean the wiper, capping station, and the sides of the printhead. Different machines had different processes for this, but typically the printhead assembly would move to the far end of the printer. This allowed the end user to see the bottom of the printhead, and to use a lint-free cleaning wipe dipped in cleaning solution (provided by the manufacturer) to wipe around the sides of the printhead to remove any built-up ink or particulate matter that might be there. The end user would also clean the tops of the capping station (or stations) and thoroughly clean the wiper. By maintaining the wiper and the capping station, the machine “cleaning” process would be more effective.
Remember, when you hit the “cleaning” button (and choose light, medium or powerful) all you are doing is jetting ink through the printhead (in different volumes) and into the capping station — as good as pouring money down the drain. So, having a clean capping station and wiper goes a long way to reducing the number of “cleanings” that need to be done at the printer. Check with your manufacturer as they will have a recommended schedule for maintenance; remember, it’s a recommended schedule, and your needs will vary depending on the amount of printing you are doing.
A Different Style of Wiper
It’s important to note here that Epson has gone to a different style of wiper, which is a wound roll of lint-free cloth that serves as the wiper. This wound roll means that you no longer need to clean the wiper as it is not needed with this system and instead is a user-replaceable cartridge.
HP uses a thermal printhead technology, which is a user-replaceable consumable. It’s still necessary to do nozzle checks from time to time so you will know the condition of the printhead and will know when it’s time to be replaced. Make sure you have a replacement printhead on the shelf with this style of printer so you don’t have downtime due to a printhead failing just as you are ready to print a critical job.
HP printers (roll-to-roll) also have a maintenance station with a wound lint-free cloth instead of a wiper, and it’s important to keep an eye on the status of this and any other consumable. Remember, the printer has a sensor monitoring the status of the maintenance station, and when it’s used up or full, you cannot print. If you aren’t monitoring this, it will occur at the most inconvenient time, rendering your printer useless until replaced.
Speaking of consumables, it’s important to be aware of your manufacturer’s definition of consumable — particularly when it comes to warranties. You should know if the capping station and the wipers are covered under the warranty (usually not). I would be wary of using non-OEM parts if you are doing maintenance and replacing parts yourself (at the very least inspect the part carefully before putting it into your printer). I have seen capping stations, which should be rectangular in shape, have an almost oval shape. This means they won’t seat properly with the printhead, and the end user cannot maintain a good nozzle check from one day to another. The misshapen capping station will allow air to dry out the nozzles, creating major printing issues — all to save a few dollars on a critical part.
Next are the industrial piezo printheads. These printheads are designed for the end user to purge ink through them and to then use a lint free cloth (while wearing gloves) to wipe along the bottom of the printhead to clean the nozzles. Depending on the print process, this may need to be done at the beginning and end of each shift — and occasionally during the day while printing. These printheads do have a capping station, but do not have a wiper; that wiping process is performed by the end user as described above. You’ll see this on many UV flatbed printers. Again, refer to your manufacturer’s maintenance schedule to make sure you are performing this in accordance with recommendations.
And let’s not forget the maintenance issues inherent with white ink (or even a metallic ink). White ink needs to be shaken or stirred in some manner on a regular basis; some manufacturers have an internal pump to move the ink through the system, while others actually agitate the ink bottles. The titanium dioxide (which is what makes the ink white) easily settles and if the ink is not stirred, shaken, or agitated then what prints is a milky, translucent mess rather than an opaque white ink.
The metallic inks don’t need as aggressive an approach, but they do need to be managed (shaken or agitated) more than typical CMYK inks. Again, refer to your manufacturer’s recommendations for proper maintenance or upkeep of white and metallic inks.
I’d be remiss if I overlooked environmental conditions and their impact on equipment maintenance. An environment that is too dry can cause nozzles to dry up and clog, and can also cause a buildup of static electricity. This is especially important with dye-sub inks. Have you ever been shocked when you walked up to a printer and touched it? When static builds up in the material you are printing on, it actually repels the ink droplets and can cause them to deflect from where they belong.
Too much humidity can also create a problem; water in the air can cause the cap tops to swell, and in extreme conditions water can collect on the face of the printhead. At the very least, have a hygrometer (which measures humidity) and a thermometer in the print room. Ideally, find one that will allow you to track both so you can see how it is trending over time.
For instance, how much do the temperature and humidity change overnight or on the weekend (for those shops that aren’t running more than one shift)? Make sure you don’t have your router or any other dust-creating device near your printer. The printheads have liquid on the bottom just waiting to attract particulate matter (such as dust) and create deflections and even clogs.
A well-maintained inkjet printer will give you years of service (and profitability) so take care of it, and create a culture that has, and follows, a process. Now go check the nozzles and get back to printing.
Ray Weiss, Director of Digital Print Programs for PRINTING United Alliance, joined the Association in 2014. He assists association members with technical information on digital printing as well as digital equipment, materials, and vendor referrals. He oversees training and certification workshops at PRINTING United Alliance along with the Association’s Digital Equipment Evaluation program. Ray is project manager for both the PDAA Certification program and PRINTING United Alliance's Digital Color Professional Certification program and is an instructor for the Color Management Boot Camps. Ray regularly contributes to the Association's Journal and won the 2016 Swormstedt Award for Best in Class writing in the Digital Printing category. Outside of work, Ray enjoys biking, international cuisine and spending time with his three fantastic grandkids.