Cameras have been used inside paper machines for decades. But, as with most technology, the evolving sophistication of in-machine cameras and the vast amount of data they can collect has made them indispensable to papermakers.
Founded as a start-up company out of Darmstadt University in Germany more than 35 years ago, ISRA Vision is now part of the Atlas Copco family of companies. As part of the Industrial Techniques division, its focus is on machine and surface vision. Machine vision and robotics were the original business. Christian Ekmeyer, product manager, says moving into surface vision was a natural extension.
Any industry using a moving web process – steel, plastic, aluminum, glass, paper – can use ISRA Vision technology. It is also involved with sheet processes (think packaging), but basically, Jorma Jaervinen, business unit manager, paper and security, says the main focus is web inspection.
The paper industry (including tissue and security) makes up about 10 to 12% of ISRA Vision’s business within the surface vision line. Ekmeyer adds that the security papers sector is a very “sensitive” business and that ISRA Vision has a major share of this market.
The company services all paper grades from the lightest tissue to heavy board. Its presence in the board and tissue markets has grown following the industry’s conversion from graphic grades.
Tissue is a special market. “You need to understand that it is not only fast running but a more difficult environment compared with traditional paper machines, specifically dust,” Jaervinen says. “From a web inspection point of view, it is the most difficult.”
For tissue machines, ISRA installs the camera and illuminator in one stainless steel housing. The number of cameras installed depends on the client and machine. “Speed is not the issue,” Jaervinen adds. “In tissue, we focus on defects (e.g., holes, edge cracks) that may affect process stability.”
BENEFITS TO THE CONVERTING LINE
The data collected can then be uploaded to the converting line. For example, if there are holes in the web and the producer is making a three-ply tissue, the layer with the holes can go in the middle.
ISRA’s inspection system cameras can achieve a resolution of 0.25 mm on a 2,000-m/min machine. Its systems can pick up the tiniest of defects not visible to the naked eye.
The poorer quality of secondary fiber has been an issue of late to the industry. “The yield of secondary fiber has been going down,” Ekmeyer notes. “You can see it in the number of defects, for example, dirt count.”
A web inspection system will help determine the quality of the furnish. But communicating that information to the producer requires a good defect classification system. “You need to say what kind of defect it is: streak, impurities, oil drops,” Ekmeyer adds. “Our software modules are very sophisticated. We use AI algorithms. It is a fully automated classification.”
ISRA’s management platform is called Paper Master and is common to all grades. A feature of ISRA’s newest technology is sync code marking based on laser technology. This mark, done on the paper machine, can be detected on the winder, which then specifies the position in the web. For example, if there is an edge crack or other defect, the laser mark coding tells the winder control to slow downer to avoid a web break. If a reel is going from a rewinder to a coater, it can be stopped, the defect patched and then sent on to the coater. ISRA has about 25 installations with the laser marking technology.
ISRA also offers an unwind control system for slitters. “With our synchronization ability, we can give an exact quality report,” says Ekmeyer. “We can also tie in other data to our software (e.g., moisture measurement), so a producer can decide whether or not the end product is saleable to a specific customer
“Everything today is about grading and detecting defects as soon as possible.”
ISRA offers its EPROMI software program as an add-on to its systems. It can display a tremendous amount of data that the mill can use for condition monitoring or predictive maintenance. The information is easy to access, either in the mill or remotely. It can also be used to collect and coordinate data from all kinds of quality control systems from any type of paper machine and/or mill.
Although the hardware for such systems is basically the same, each installation depends on the needs of the client. “We have a lot of standardized systems for web monitoring, to look for web breaks,” says Ekmeyer. “For tissue, we have a standardized system depending on trim size.”
There are specialized systems offered for specialty machines that are custom designed depending on space and configuration. There are different paper quality needs for different grades. Therefore, ISRA will target the defects a mill is specifically looking for. For example, coating on high-end broke will need a high-resolution system. Correct installation is essential, e.g., camera angle.
“We know most of the defects,” Ekmeyer adds. How the producer does final surface treatment also has an influence on the kind of optical set-up it needs. “We do laboratory tests to determine the set-up,” Ekmeyer says. For web inspection systems, ISRA builds its own cameras.
Installing a system is obviously easier when it is integrated with a new paper machine. “Older PMs can be difficult because of space constraints,” Jaervinen explains. “We need to get the right resolution at the right speed for the right application/position.”
MORE TO EXPLORE
As technology evolves, the amount of information available grows and grows. But, sifting through it to ensure that the customer has the right information to improve operations is what’s important. “We can create a huge amount of data,” Jaervinen says. “But we need to screen that data to ensure the focus is on what’s important. The software is so important now.”
With machine conversions, particularly from graphic to board grades an ongoing trend, there is a need to ensure the legacy web inspection system meets the new needs of the client.
ISRA’s systems allow a mill to handle data, correlate data (paper quality management system) and interface between ISRA’s systems and the mill’s QCS. Predictive maintenance based on what is seen and what can happen next is another benefit. “We not only give eyes to production but can also provide solutions for potential upsets,” Ekmeyer adds.
Another new twist to the technology is the introduction of color cameras. This provides more information about the defect. It can distinguish between oil and water drips on the web. For recycled mills, it can also identify bacteria early: Is the mill’s deinking system working well or not?
By using ISRA VISION’s Paper Master Platform, papermakers will be able to optimize their entire production process by reliable process efficiency and quality control.
About ISRA VISION
ISRA VISION is a globally leading supplier of optical solutions for 3D machine vision and surface inspection. www.isravision.com
Graeme Rodden has covered the pulp and paper industry for more than 40 years, including serving as editor of several well-known paper industry magazines.