Most issues can be avoided or easily fixed by knowing how to detect early signs of printhead performance trouble
PRINTER LIFE: QUALITY ASSURANCE TIPS, TRICKS, AND BEST PRACTICES
Having a great printer is one thing, getting the best out of that great printer is something else. Even the most reliable printers out there need a bit of maintenance from time to time, a little bit of tender loving care to get them to perform at their maximum for the longest amount of time possible.
And it’s worth it. Consistent print quality is dollars in the bank
Chargebacks. The word makes even the most experienced and worldly of CEOs and managers cringe. Many retailers levy chargebacks, or even worse, altogether refuse the shipments of cartons if their identification does not meet regulation. Many a company has paid a high price for shipping cartons with non-compliant labels with poor print quality.
Non-compliant labels are not easy to spot. What ‘looks’ like a perfectly normal label to the naked eye might in fact be faulty when seen through the eyes of a scanner. Underburn, overburn, unwanted diagonal lines, spots or voids present in the image, an unsustainable wide/narrow ratio, or poor edge definition could all end up costing tens of thousands of dollars in chargebacks and delays.
Making sure that your printer is in tip top shape can prevent these errors from occurring. The printhead is the most important part to maintain and replace. The majority of problems stem from improper use or care of the printhead, and most issues can be avoided or easily fixed by knowing how to detect early signs of printhead performance trouble.
Underburn
Underburn is when the dark bars print to lightly. This doesn’t provide enough contrast to the light spaces. This condition is reflected in the Print Contrast Signal measurement specified in the ANSI print quality guidelines.
Underburn is usually caused by two things. Uneven or insufficient pressure is being applied by the printhead on the material. A simple adjustment of the printhead pressure will remedy this situation.
The other common cause of underburn is that the heat is not set high enough to properly change the direct thermal stock or melt the ribbon for thermal transfer printing. Heat setting are adjustable, and little tweaking should allow you to attain optimal contrast.
Overburn
When heat is set too high, the black bars come out too thick. That’s called overburn or ‘bar growth’. This causes the bar code not to conform to specs and become unreadable as the wide/narrow ratio cannot be maintained. A simple adjustment to the heat setting should correct this issue as well.
Diagonal Lines
Sometimes unwanted diagonal lines or a white streak may appear on labels. This is a sign that the ribbon is either not loaded correctly or is not feeding correctly. Look at the ribbon to make sure it’s smooth, and confirm that the label material is loaded properly within the guides and is being fed into the printer smoothly and cleanly.
Spots or voids in the image
If you’re suffering from spots or voids that usually indicates that there is dirt, abrasion, or burnt out elements on the printhead. Burnt out elements prevent the heat from transferring, and dirt or abrasives block or redirect the heat or ribbon transfers, both give you dead spots on the label which could make it unreadable by barcode scanners. Lines or streaks are usually caused by a wrinkled ribbon.
Regular cleaning will take care of the dirt and abrasion issues. Tightening the ribbon, or reducing print speed will most often take care of the streaks and lines, however, burnt out elements will require you to replace your printhead. Lastly, spots or voids could also be caused by an improper or defective top coating of the media being printed on. Test with a new roll of media to see if the issue persists.
Unsustainable wide/narrow ratio
Underburn and overburn can cause an unacceptable ratio to emerge between the wide and narrow elements of a bar code. A good tip to maintain proper bar code print quality is to create symbols with the highest wide-to-narrow ratio that both the space on the label and specifications allow. Symbols are becoming smaller everyday, so reading tolerances are becoming more and more acute. The wide/narrow ratios can be enhanced and made more consistent by increasing print resolution.
Poor edge definition
In order to decode a bar code properly, a bar code reader needs sharp, well-defined edges to distinguish between the bars and spaces on the bar code symbol. A reason why thermal technology is best for barcodes is due to the straight, sharp edges it produces.
If you have rounded or fuzzy edges, you can usually correct that be reducing printing speed. But another less known reason for poorly defined edges is an unmatched media and ribbon combination or poor quality labels or ribbon material. Using good quality materials made to work together not only improves the quality and readability of bar codes, it will also prolong the life of your printhead.
Generally speaking, printing bar codes vertically, like a ladder, can also cause edge definition problems, so going horizontally, like a fence, should be considered whenever possible.
All these conditions should be watched for regularly. The basis of an effective proactive quality assurance program would consist of visually inspecting labels as well as performing print tests. A safe and responsible guideline to follow is to monitor and inspect print quality every time the printer is started, at the beginning of every shift, and every time the label media or ribbons are replaced.
IMS has many programs designed to prevent these types of costly errors from occurring, and we custom design each preventative maintenance plan to the specific needs of our individual clients. If you have any questions about the maintenance and upkeep of your labelling equipment, please let us know. It will be our pleasure to make sure you’re getting the most out of your equipment for years to come.
