Producing high-quality labels is something we strive for here at Skanem Africa. Achieving that has much to do with meeting the specifications and requirements set by the customer. To avoid and minimize quality issues along the way, a smart defect detection system helps ensure that all stages of the printing process work seamlessly.
During a printing session, it's essential that all the processes work together smoothly. Sometimes, the printing machine might not behave as anticipated. If there isn't a good quality assurance system in place, this can lead to inefficient runs, unwanted results, and unsatisfied customers.
When errors occur, a defect detection system lets you know the cause of the error so that corrections can be implemented quickly to ensure that the label’s shape and design follow the requirements made by the customer.
Common label printing defects
Most printing defects that can prevent you from achieving your intended results are mainly associated with the type of printing technology used and the label graphics.
Cutting tool errors
Certain labels, such as stickers, require a cutting tool to cut the label into a specific shape and size. These are typically applied to lubricants, edible oils, and homecare products. There are three types of defects associated with the cutting tool:
- Label-cut: When the tool doesn’t cut in the right place.
- Deep-die cut: When the tool cuts the stock and the liner instead of just the stock.
- Deep-die impression: When the cutting tool cuts beyond the stock and puts heavy impression marks on the liner. In these cases, the label can no longer come out of the liner for smooth label dispensation, sticking to the liner instead and rolling back with the waste.
For instance, glass bottles are normally labelled in batches of tens of thousands an hour. If the labels aren’t dispensed due to deep-die impression, some bottles will continue into the next step of the process without a label. A machine operator must then apply them manually. Thus, this defect makes the entire process incredibly time-consuming and inefficient without a defect detection system to notify you about the error in time.
Colour variation
Customer specifications decide which colours should be used and combined. The difference between the customer specifications and what is actually being delivered is called colour variation.
The printing technology determines how the colours must behave during a printing session, and this is where a mismatch might occur. If the colours deviate from the customer’s requirements, the label won't turn out as intended.
Misregistration
Achieving the correct graphics for your labels requires the composition of several colours. Misregistration occurs if the colours are not being printed back-to-back in sync during printing.
Misregistration can make the label useless and unreadable due to smushed letters and colours.
Read more: How much should your labels be able to endure?
The three stages of a defect detection system
Because the printing processes synchronize from start to finish, so must the different stages of the defect detection system. Although each stage has specific functions that help reduce quality issues during every step of the label printing process, the last two stages are interconnected.
Printing Press
Prior to any printing run, the machine is set up to match the customer’s specifications. The system then takes a reference image as a golden copy, so the detection system and installed cameras always monitor and continuously compare the run to the reference image.
In case of deviations, the system sets off an alarm and the defect detection system’s visual alarm on the printer changes from green to red, and buzzers release an audio alarm. There is also an alert on the screen that shows you the error, which the machine operator can use to identify and implement the right measures for corrections.
Read more: How to make your packaging and labelling stand out from the crowd
Editing Desk and Finishing Workflow Link
During the printing process, every finished roll is numbered, and the first defect is placed in front of the camera, a few meters from the roll end. This information is used both during editing and finishing workflow as a reference for a first defect to synchronize all other defects.
At the editing desk, the quality personnel will allow what is within customer specification’s limits and decline what isn’t. When working on the finishing of printed rolls, the rewinding machine will stop automatically when it reaches an area with a defect that has been declined at the editing station.
Quality assurance report
Moving through the printing press, editing desk and the finishing workflow link, the defect detection system gathers information to generate a quality assurance report at each stage and for each roll. The report shows the extent to which the labels conform with the customer’s specifications, with a percentage of good labels per roll out of a 100 per cent ideal.
At the editing station, the editor must decide whether the remaining defects are within the customer’s specifications or if changes must be made. If the defects do not alter the intended results, the label rolls are sent on to the finishing workflow link. During this stage, the defect percentage is likely to reduce.
Read more: 3 approaches to brand consistency for brand owners
Although a defect detection system functions as a safety net to identify and fix errors, both the operators and the machines must work together. At Skanem Africa, we always strive to produce the highest possible label quality for our customers by ensuring that machines and operators are in sync and meet your label requirements.
If you wish to learn more about how we quality assure our labels, feel free to contact us.
