Thermal printers are great at printing bar code labels and tags, but do you have the repair technicians out often to work on the printers? There are some easy to follow tips that can maintain your print quality and maximize the life of the components that wear out like print heads and platen rollers.
Thermal printers are used in many industries and come in many shapes and sizes. From the little desktop units provided by shipping companies like UPS or Fedex to the larger units that can be used as integrated or stand alone printers in packing, warehouse and/or production environments. There are two ways to use thermal printers. Using a thermal printer with an ink ribbon is called “Thermal Transfer” printing. In other words, the printer passes the heat from the print head to a ribbon that melts the ink at a specific temperature and “Transfers” that ink to a media substrate such as a label or tag. The other method is “Direct Thermal” printing. This method does not use a ribbon. To use direct thermal printing, the media (Labels or tags) needs to be direct thermal media. This type of media has a “Thermal Sensitive” chemical coating that turns color at a specific temperature, the most common color being black. The printer passes the heat from the print head “Directly” to the media and it’s the media that changes color in response to the heat of the printer.
Tip 1: Keep the print head clean. Read the operator manual and follow the manufacturers recommendation for cleaning the print head. In general the head should be cleaned with Isopropyl alcohol of at least 70% concentration. For thermal transfer printers the print head should be cleaned when you change the ribbon. For direct thermal printers, the print head should be cleaned when you change the media.
Tip 2: Do not use sharp objects to remove label jams. Thermal printers have a platen roller, that is made of a rubber compound that pushes the media out the front of the printer. This roller also provides counter pressure to the print head so you have even print. If the roller is cut, this soft spot will not print clearly and will show as a repeating faded spot in a label. This might not be a big deal for descriptive labels, but It is very bad for bar coded labels. Also make sure to clean the platen roller with alcohol once a week to avoid build up of residues that might cause problems in the long run or any time you have label adhesive stuck to the roller.
Tip 3: blow away the dust at least once or twice per month. Dust in the air as well as dust on the media will accumulate in the printer over time. The dust build up can cause print quality problems as well as sensor issues. To blow out the printer use a dry source of compressed air. Either a can of air or from a compressor. If you use a can of air, make sure that you don’t spray the liquid of the can in to the printer. This will instantly freeze and cause a moisture build up when it thaws out. If you use a compressor, make sure that there is a moisture trap / filter that will keep moister from spraying out the nozzle. Make sure not to let the dust settle back down in to the printer after blowing it out. It is common to have poor print quality for the first few labels as the dust got blown in to areas that fall on to the labels when printing. It is often a good idea to feed or print a few linear feet worth of media to clear out any remaining loose dust in the printer.
Tip 4: Know the resolution of your printer. 203 “Dots Per Inch” (DPI) is a standard resolution for thermal printers. This resolution is good for larger labels or labels with bar codes of low density. Another common size is 300DPI. This resolution is good for most large to mid size labels with medium bar code density. Some manufacturers make print heads with a resolution of 600DPI or higher. These are good for small labels or bar code labels with high density. As the resolution of the head increases, the replacement cost of the head increases as well. Also, because the higher resolution has more data to process to create the print image. As a result, the maximum print speed usually decreases.
Every manufacturer has some slight differences on user maintenance. I recommend following the instructions listed in the user manual. In the case of not being able to find a user guide or manual, these tips will help maximize the print quality and the life of the wearable parts of a thermal printer.