Best Practices: More Than Just Defect Detection
In an industry where making a mistake or producing a defective product can be both costly and embarrassing, it’s essential to implement available tools that can help avoid these problems slipping through the cracks.
In the package printing business, an inspection system not only serves as a safety net to catch errors, but is even better used as a data collection tool that can help improve efficiency and reduce waste. Guy Yogev, marketing director for Advanced Vision Technology (AVT), explains that reducing time and material waste costs need to be top priorities for converters, and by using an inspection system to the best of its abilities, operators can pinpoint print defects, where they’re occurring in the process and decide how to fix them quickly. Understanding this data, Yogev says, can help reduce makeready time, downtime and material waste.
“I think [waste reduction] is No. 1 in terms of putting an inspection system on a press,” Yogev says. “That’s mainly what you want to achieve. You want to reduce waste and find those defects very early in the process — before they become waste — and if possible, try and fix it without stopping the press.”
For operators to fully understand that an inspection system is being used to its full potential, Yogev explains that they need to conduct a thorough analysis of the data logged by the system.
For example, he says that if an error is detected that consistently repeats itself, it can be a clue that there is an equipment or process problem that needs to be addressed on the press.
“Some of the analysis and improvement needs to be on the press,” Yogev says. “If I’ve got some repeating issues on the press, if I find those issues, it is not enough since I don’t want to repeat the same issues over and over again on the same job or new jobs on the same press.”
Yogev explains that it is also important to be able to interpret data to understand if a defect is an isolated incident or if it is a more pressing issue that needs to be attended to before it becomes waste.
With an inspection system, Yogev says, an operator can tell exactly what is causing the defect and can think quickly about how the problem can be addressed.
“If I’ve got a gravure press and there are some ink splashes every once in a while, in many cases, there’s not much you can do about that,” he says. “The logged information can be used later on to improve processes, and also to automatically control and stop finishing equipment downstream to remove the defective material prior to shipment. This is a major benefit to printers to help them improve the processes and to ship defect-free material to their customers. If there are some doctor blade streaks or hazing, it can be fixed before it becomes waste. It needs to be very clear to the operator that is the issue and he can go and fix it.”
Jonathan Hou, director of technology for GlobalVision, explains that at first, some operators may be hesitant to embrace an inspection solution. For example, if he or she is used to a manual process of defect detection, it may take some time before an operator fully trusts an inspection system. But, he says, when the results come in, operators tend to realize just how much more efficient they can become.
For example, Hou says manually proofreading a press sheet for errors in text, images, braille barcodes and spelling, could take an hour, with the potential for human error. But, with an automated system, this process can happen in less than 10 seconds with 100% accuracy.
“There may be some reluctance from someone who is used to a manual process to gain a trust with a machine-based system,” he says. “But by automating the process, you’re catching a lot more with more accuracy than your manual process and you are doing it in less time.”
Inspection Across Print Types and Applications
Because package printing involves several different print methods, substrates and applications, the inspection process needs to be in tune with what is being produced. For example, Hou explains that as regulations and legislation change in various markets, printers can focus their inspection process on key areas to make sure they are in compliance with requirements.
“Pharmaceutical is traditionally where a lot of the need for inspection came from,” Hou says. “But we’re also seeing a lot of interest from different consumer companies as well. With the new food regulations coming out in terms of nutrition facts, those are things that are being looked at very heavily. You don’t want to make mistakes with nutrition facts.”
In addition to different issues that can occur across end-user markets, Yogev says that inspection can help solve specific issues in different printing processes. For example, he explains that in flexography, plate pressure or dirty plates can be the cause of defects.
But, as digital printing gains traction in the industry, he says inspection systems have had to be developed to accommodate the needs of both electrophotographic systems and inkjet.
“Each one has it’s own unique issues that need to be controlled,” he says. “Some are press driven and need to have a closed-loop camera based system. This is mainly on inkjet when they have to really make sure the nozzles are not clogged or weak. This is the main issue in inkjet printing. So you have to develop the technology, the algorithms, and the complete platform to adapt to different print technologies.”
A Boost in Morale
By having follow up conversations with printers and converters who have installed inspection systems, Yogev says he often finds that there are some unexpected benefits that come from the addition of inspection.
He explains that when operators are provided with high-tech equipment that helps them do their jobs better, it adds to the enthusiasm and morale in the production room. In one specific instance, he says an AVT customer analyzed their processes before and after adding inspection to one of their presses. The new capabilities caused the operators to work with a renewed fervor, which in turn, improved production quality overall. It also helped printers to train new employees on the press faster and more efficiently.
“They said one of the major issues they saw was the enthusiasm of printers,” Yogev says. “With the better training and better adaptation printers had, the better [the] result they had on the press when they put inspection in.”
Whether it’s catching errors up front or using inspection data to ensure defects are minimized, Hou says stringent quality control is essential in keeping businesses ahead of the pack.
“You’re always trying to increase quality in your business,” he says. “There are a lot of printers out there and it’s quite a competitive landscape. Quality is very important if you’re trying to win business from customers. You want to have pristine quality when you’re printing and you want to make sure no errors go by.”
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