An often overlooked problem is the possibility of applying the wrong labels to the wrong product. The agility many manufacturers have achieved with just-in-time (JIT) manufacturing can come at a price with label application errors. Often we think of label errors in terms of the wrong data getting on a label. However, short runs of similar products open the possibility that we can print the perfect label but still get it wrong by affixing that label to the wrong product. Taking steps to analyze your label process and find weaknesses can help you eliminate or at least reduce the possibility of printing right but applying wrong.
Common Reasons for Misapplying Labels
- Not Clearing “Leftovers” from the Workspace – Some discrete manufacturers will print all the labels for a particular lot or batch in advance of the work. Then, when the work starts, the labels are applied to the products as produced. In many cases, however, the exact number of products to be produced is not known until the lot is completed. Thus, there may be some extra labels. If those ‘extras’ are not cleared from the work space before the next batch or lot is run, it is possible for labels from the prior batch to be accidentally applied.
- Labels Lurking in Printer Memory – Most thermal printers will store, temporarily, print job information in the printer’s internal memory. Typically this is very helpful. If the printer runs out of labels or ribbons (or just prints too slowly) we don’t want labels to vanish into Ether-space. However, there are situations where the print user is not aware that labels are sitting in the printer memory. For example, if a person prints a job with 3000 labels and the printer runs out of labels at 2998, the print user may not notice the printer is out of labels and just take the 2998 labels without resetting or restarting the printer. The next person, running another large label job, may notice the printer is out of labels (thinking the prior user left it empty), put in a new rolls, and assume all the labels streaming out belong to THEIR print job. If they are not careful, they may not notice that the first two labels (#2999 and #3000) are NOT part of their print job.
- Label Jobs Running Together – Often thermal printers are shared by multiple users. If two print users send different print jobs to the same printer at the same time, it may be hard for one person to notice that they are picking up TWO print jobs. When the labels are applied, if the labels are similar, the person applying them may not notice either. Even if they check the first label and it is accurate, they could easy overlook when label job #1 stops and label job #2 begins.
Ways to Reduce Mislabeling
- Print labels on demand – One of the most effective ways to eliminate the misapplication of labels is to avoid printing them in advance. Labels should be printed as close to the exact application time and location as possible. This helps eliminate the ‘clear the work space’ problem since there will be no ‘extra’ labels floating around the production floor.
- Automation – There are many ‘label applicators’ on the market. Using a machine to apply labels helps to make sure the label is quickly and consistently applied to the right place on the case each time. If set up correctly, it can also help make sure mistakes are minimized. Print applicators can be the best of both worlds. They can print label the labels on demand (see #1 above) AND apply them automatically.
- Verify labels using barcode scanning and / or vision technology – Technology such as barcode and vision allow labels to be quickly and accurately scanned and verified. Tightly integrated systems will read the label immediately after application to ensure that the label is actually on the product in the correct location and match the data read to what is expected. Systems that detect correct label application can either signal users of a problem or generate a copy of the label somewhere else downstream so someone can reapply it.
- Make sure the printer is clear of print jobs before printing – This may seem too obvious. However, it is easy not to notice the printer is in an error condition at the end of a print job. Or, for print applicators, the printer may be waiting for a photo sensor to trigger the next label. You may not be able to ‘see’ that other label(s) intended for other products are still waiting to be applied. Of course training users to verify that the printer is back to the default “Ready” or “On-Line” state is important. We can also send special printer code instructions, embedded in the label, to tell the printer to clear all previous print jobs assuming the printer is not shared with others. For more information, see Clear Printer Memory to Prevent Misapplied Labels
- Print a start / end label – Most industrial label software applications can print a ‘start page’ and/or ‘end page’ label. These start and end labels can be designed to look very different from the label design template so they stand out to the print user. This helps the user by conditioning them to look for the start label before printing and to stop when the end label is seen. Printing a start and/or end print label can be especially helpful in situations where ‘on demand’ label printing (see #1 above) is not possible or practical. For more information, see Use Start and End Labels to Prevent Mixing of Label Jobs
As you can see, printing the perfect labels does not mean the labeling job is complete and thus label problems can still occur. Making sure you apply the label correctly is just as important. There are many ways to misapply labels. However, working with your labeling system integrator should help to reduce the chances for this to occur and, therefore, keep your labeling system as efficient as possible!