It is not just to please the customer that converters have invested in web inspection and control systems – efficiency is the name of the game
Web control, whether it tackles surface detail or inspects, monitors and then closes the loop on colour and print defects, is essential in today’s quality conscious retail businesses. Inspection processes are increasingly essential to ensure that production and quality objectives are achieved on a consistent basis; preventing defects from occurring that would mar pack presentation if left undetected.
Stopping defects in their tracks before hundreds of metres of waste are produced also makes commercial sense. Equally important is the ability to improve processing speeds. The new generation 100 per cent automated web inspection systems developed by Futec are said not only to detect and classify printing and/or material flaws, but also produce reliable process documentation. Real time trends are plotted that verify any developing problems, and statistical data is collected so that quality improvements can be made, essential given the ISO accredited requirements of so many customers, says the company.
Its in-line systems are currently used for inspecting a diverse range of materials from paper, foil, translucent or opaque films, and non woven fabrics. Flaws such as discoloration, doctor blade defects, fish-eyes, fogging, foreign matter, ink-bleeding, ink splashes, mis-registration, missing print, pin holes, scumming, splices, spot defects, staining, streaks and tears can be spotted.
These automatic flaw detection systems provide more automation while maintaining or enhancing product quality. Automation allows waste or defects to be automatically identified and then separated or eliminated from the production stream. The systems minimize operator involvement, and are intuitive to use; in operation they enable production speeds to be increased with confidence, with throughput easily monitored.
Using line scan camera technology, the web passes continuously over an array of line scan sensors illuminated by a line of light. This allows the whole width of the web to be monitored so that even random defects can be detected. This differentiates the EasyMax (printed web) and Fmax (surface inspection) from other systems, which use moving cameras, mounted on manual or motorized traverse bars. Those types of systems can only undertake a sampled inspection with no guarantee that random defects will be detected, stresses Ray Scragg of Futec Europe.
Specialist in the design and manufacture of web inspection and registration systems for the coating, laminates, security and fine paper markets Norcan claims to offer systems that are easily integrated in today’s high speed production processes.
“Manual inspection is time consuming, labour intensive and inconsistent whether on-line or off-line. Charge backs are expensive,” says Royston Cook, director of sales and marketing. “Our systems can help make these problems a thing of the past. Manufacture and converting is a complex process, added value features are applied at various stages of the production cycle. And quality is important at each stage.
The company offers a range of systems capable of detecting flaws such as dirt, holes, tearouts, creases and coating defects. And proven systems are available to verify visible security features such as windowed threads, iridescent and foil bands, as well as watermark dimensions and registration. After analysis of customer samples on its dynamic rig, the company will recommend a suitable system that can be integrated into the process with the minimum of disruption. This will include advice on and supply of illumination – critical for each application, stresses Norcan.
Systems provide live images of defects, and alarms for product with gross, repeating or continuous flaws. The “flaw log” indicates the cross machine and machine direction position of each defect. This allows informed decisions to be made by management regarding quality of the product prior to shipping. Information is available through a network connection to authorized personnel and can be archived, and analyzed later, in the event of a customer complaint.
Where the system is installed on a sheeter, or other sheet-fed machines, the defect is tracked and the sheet rejected.
AVT reports record sales for last year – a year that included successful product launches and the acquisition of Geiger Vision Systems. It now boasts 600 installations worldwide. At IPEX it announced the development of ReColor, a closed loop solution using viscosity and cylinder control to achieve the required colour quickly in set-up and ensure stable colour during the run. Intra-Repeat, a system designed to control left-right pressure balance on each cylinder, was previewed. This is said to help press operators achieve consistency across the web when printing different products on the same repeat. And Delta E capability provides an effective means of communication with customers who specify jobs in Delta E language.
Label product development and penetration of the labels printing market is built on the success of the PrintVision/Apollo-Labels inspection system, adds the company. Co-operation with rewinder manufacturer Arpeco and the acquisition of Geiger strengthened its sector presence.
Inspection of reflective material has been a challenge, but now a solution has been found that delivers the same level of automatic inspection for reflective materials as is possible on other substrates, says AVT. An LCCD reflective camera and illumination head is now offered as an option for PrintVision/Argus and PrintVision/Apollo solutions. Benefits are claimed to include reduction in waste of expensive reflective substrates, consistent higher quality over the full web width, increased confidence in print quality that results in increases in press speeds, better press and labour utilization and last, but not least reduced customer rejections. Eleven of the reflective support modules were sold in 2002. These included systems to Neophan, Italy, Bagel, Germany and Ultra Packaging, of the USA.
TruColor Vision Systems has added full closed loop automatic register control for establishing and setting colour register on press to its range of TG 4000 Series web inspection systems. The series has undergone a complete operator interface re-design in the Windows NT operating platform, reports the company. The operator can easily and quickly call on the features by touchscreen interface, it adds.
This new register control feature is claimed to offer converters much faster set-up times and reduced waste due to registration error. Additional enhancements have been incorporated into the TG 4000 Series Automatic Color and ANSI Bar Code monitoring software, including new Image Stabilization capabilities. These features have generally been targeted to offer much quicker and easier job set-up, storage and recall specifically for short to medium press production runs. An audible /visual alarm beacon notifies the press operator when pre-set defect tolerances have been exceeded.
PC Industries offers high speed digital cameras for its Viper print inspection system which are claimed to provide 100 per cent defect detection of a printed web at speeds up to 2,000ft/min. The system may be configured with up to 12 high resolution cameras and, importantly, stresses the company, can merge the camera images cross web and down web. This allows for variable repeat sizes and also gives the operator an overview of the entire repeat. The system is claimed to be easy to use and can be customized for most applications.
A new camera enclosure developed by video web inspection pioneer Tecscan Electronics provides the operator with a choice of illumination techniques, thus enabling the system to inspect many different types of products.
Managing director Malcolm Lear says that as designers of packaging and security products become ever more resourceful, the printer and converter may be called upon to employ reflective inks, process a highly reflective substrate or use various varnish densities, fluorescent security inks and multi-angle holograms. To produce and inspect these types of products, a variety of illumination techniques are increasingly necessary to guarantee inspection integrity. By providing a range of illumination systems with the camera enclosure, the operator has a range of solutions available for these challenging requirements, says the company.
The camera enclosure can be integrated with TecScan’s ColourScan range of video web inspection systems, from the entry level, high specification CS1 for narrow web through to the Avis, an advanced automatic inspection system for flexible packaging, wallpaper and folding cartons. Other systems that will benefit from this new development include the Avis Combi – a dual video web inspection and registration control system for ‘gearless’ flexographic presses.
Basler Vision Technologies has added a new option to its automatic web inspection system – the Websight. The newly integrated OPC interface allows direct communication of the web inspection system with an automated process control, for example WinCC. Thus, explains the company, monitoring and control of the web inspection system can be integrated in the local process visualization software. An alarm generates a warning on the WinCC and after investigating and acknowledging the warning the operator can clear it directly at the WinCC. “This and other options such as the EasyTeach function result in an important quality and yield improvement of a large variety of converting applications,” says the German based company.
“York Electronics Centre, in association with Faraday Packaging, has several clients pursuing our Micro Profile monitoring techniques to deliver improvements in product quality and manufacturing efficiency,” reports marketing manager Alan Gobbi. Offering continuous measurement across the web, it can be used with a wide range of production processes, including coating, laminating, slitting and web production.
The system is claimed to be ideally suited for in-line real-time assessment of planarity and tension in web material. “Current planarity measurement techniques, such as flatness, camber, curvature, baggy lanes or tight lanes, are time consuming and often involve the analysis of a section of material removed from the roll. Tension measurement systems tend to be mechanically based, looking at average values, whereas this system provides real-time information with much finer resolution across the width of a web, he says.”
The technique works by deflecting the material using a stable cushion of air and monitoring the distortion of either a collimated line of light projected on to it or the reflected image of an illuminated line. The distorted line image is continuously captured by a computer that converts the information into meaningful tension and planarity values. Viable for a wide range of clear, opaque, shiny or matt materials, including paper, metal foil, plastics film and textiles, systems can be customized to suit specific industrial applications, adds York Electronics Centre.
Scalar Technologies reports a new thickness measuring system for ultra thin coatings. “The revolutionary ScalarGauge Fluorescence System has broken technical barriers for in-line thickness measure-ment. With a capability to measure coatings as thin as one nanometer, at the highest line speeds, the system is a world’s first when competitive products struggle to get below one micron – a thousand times less sensitive,” boasts the company.
In many industries, on-line measurement of coating thickness (or coating weight) has presented unusual difficulties. This is particularly true when the carrier is a transparent polymer based material. These difficulties arise from the very thin coatings applied to polymer substrates and poor discrimination between the thin coating and the transparent carrier. Standard methods of thickness measurement have proven unable to make reliable measurements when faced with these challenges, says Scalar. The new sensor is based on a visible fluorescence principle, which allows such measurements to be made. This is achieved by lightly doping the coating material (parts per million) with a fluorescent dye. The dye is then excited by visible radiation, with the magnitude of the emitted fluorescent radiation being proportional to the thickness of the coating.
This new device covers a range of applications within the hot stamping foils, food packaging industries and certain sectors of the security printing industry. In manufacturing industries these coatings can range from a few tenths of nanometres to a few microns. The market is demanding the ability to monitor coating weight on-line in an effort to improve quality and reduce financial losses arising from wastage, replacement and loss of manufacturing time. The system also measures standard coating and film thickness with a consistent level of accuracy. Claimed to be intrinsically safe, it can operate where others cannot, for example areas with high solvent concentrations.