Reducing waste and maintaining quality is often down to good web handling and inspection before costly damage is done
Philip Fletcher, of Arrowhive Equipment, there is almost never one absolute solution to web handling problems: “There are simply too many variables that affect web performance”. Nevertheless, he believes that operating a checklist system or even a simple walk around the machine can be enlightening. For example, machine alignment is an often overlooked variable. If machine stands are not properly aligned, purchasing additional equipment such as rollers or tension control equipment to solve a web handling problem may be wasteful.
Inaccurately wound parent rolls can introduce a form of cylindrical geometry on the line that may cause problems. Excessive parent roll run-out can generate vibration and web flutter, and may even result in wrinkles throughout the whole run. There are several solutions, one of which, says Philip Fletcher, is to consider using Montalvo’s new generation D-3100ce dancer controller or DTI-300ce dancer controller with tension indication. Available in the UK and Eire from Arrowhive, or in the rest of Europe from Danarota Technic, these controllers can help adjust for much of the tension variance coming off the parent roll.
“Tension is so often the factor in poor control,” he states. Excessive tension can contribute to web marking by pulling on the web and intensifying any flaw that may be in the roller’s surface. Excessive tension can also wrinkle, stretch or break the web and cause unwanted roll deflection. Excessive tension can come from too much drag on idler rolls or from too many idler rolls between drive sections.
Lack of tension causes ‘bagging’ – that is the web edges will be loose while the centre is slack. The opposite can occur also. Baggy edges will result in concave looking finished rolls – with thicker edges. Loose webs can lead to folds, creases and wrinkles.
A lack of sufficient tension can come from loosely wound parent rolls, from unsupported spans of web travel, from drive sections out of sync, and/or lack of nip or web pull through the line.
“Fortunately, today manufacturers such as Montalvo have developed a range that can solve the problems associated with tension control. Load cells, which can be sited in confined spaces, are becoming more widely accepted because of their ability to measure ‘actual’ tension. The information being relayed for corrective action to a controller such as the X-3100ce, an analogue controller with digital parameter handling and progressive PID (Progressive Integral Derivative) control. This and other controllers incorporate features such as transferable memory card, RS-232 interface to computer or plc and on-board DeviceNet and Profibus DP fieldbus connections.
CMC Europe has introduced the Slim Cell in Europe. Successful in the USA and with a new low profile, it sets the standard for either new machinery or for retrofits where space is tight, claims the company. It has been designed to reduce the required side frame-to-side frame width of the machine, and is thinner than others in the marketplace. Of corrosion resisting stainless steel and completely sealed to resist water migration, it is said to be ideal for use in demanding industrial environments. The Slim Cell transducer can be used with either rotating shafts or dead shafts, which makes it easier to install with less machine modifications. And it can be aligned after installation so that the maximum tension signal output is obtained at any web force direction.
It includes a small diameter pre- lubricated bearing with very low friction. So it is said to be ideal for low tension applications with rotating shafts where the size of the bearing and friction become a major contributing component to the web tension. The Slim Cell design enables it to be mounted either inside or outside of the machine frame, thus simplifying installation. The transducer has force ratings from 45 to 4500N, to accommodate a wide range of tensions. With a mechanical overload capacity of at least 500 per cent, it will give reliable service on any converting machine, boasts CMC.
Magpowr has introduced two powerful on-line tools to assist in the selection and operation of torque and tension control components.
New application software enables users and distributors quickly to determine the sizing requirements for brakes, clutches and load cells. While this software doesn’t select the product for the user, a summary sheet details the pertinent information so the ‘calculated’ output can be applied and a model number selected. Available on-line is an interactive demonstration of Cygnus, the company’s latest tension control technology. End users can experience the ease of weightless load cell calibration by walking through the control module as well as walk-through common set-up and operation screens.
Darrell Whiteside, product manager says: “The interactive Cygnus demo gives users an opportunity to see how easy the prompts are to work with. It’s not enough to hear about it, they want to experience it as well.”
Erhardt + Leimer stressed the importance of quality during the ICE show in Munich, recently. “Consequently our most important product at the show was the Elsis surface inspection system,” says Dirk Schröder, sales division manager paper and film. “The camera can see everything, but it is what we make of the information with the software that is important.”
The software package has been reviewed and the series of functions has been considerably enlarged. Systems now offer solutions for the most varied of applications, for example, paper production and processing, hygiene non wovens manufacture and processing, film extrusion, film coating, food packaging and pharmaceutical films. Product quality of webs and sheets can be proven and certified under DIN EN ISO 9001. Roll zoom, single roll protocols, extended statistical functions, low contrast streak detection and the recognition of repetitive errors are just a few of the special features of this new generation, says the company. All the data captured by the inspection system is stored in a data base from where it can be further processed with programs such as Excel or Access to generate custom-specific protocols.
Labels in mind
Special system architecture allows for quality comparison between different production lines and production sites, for an exchange of experience between different inspection systems and for a reliable exchange of recipe and parameter settings. And Elsis can be combined with additional detection systems to meet specific requirements.
Specialist in web inspection systems for labels, packaging, security and forms markets, Tectonic International intro- duced its Jaguar system, at Labelexpo. Designed to provide effective visual inspection and “active” defect detection which automatically inspects 100 per cent of the web, the system is operated using a touchscreen with a TFT screen for job set-up.
A monitor is installed on the press for print monitoring. The company’s own industrial standard Windows NT based distributed processing system includes a multiprocessor to control and service events in real-time, performing different analysis on common images using only one progressive scan, digital camera as standard.
Open system architecture allows the system to be upgraded with additional plug-and-play modules to provide a cost-effective, versatile quality control tool for bar codes, pharmaceutical codes and print defect detection.
Understanding true cost
Colour monitoring analyzes regions of interest for RGB, hue, saturation and intensity variance from a ‘golden colour template’. Prime advantage of the system is that it not only provides “passive” and “active” inspection and colour monitoring as standard, but also an accurate history of the job, says the company. It downloads required statistics taken on-the-fly and stores the information on-line or off-line through any remote PC or by use of the factory SPC system. “This choice of ‘job-save’ features helps manage press production, prove to customers dedication to quality improvement and assess the results for a full understanding of the real cost of the job,” says the company.
Paper web inspection is necessary for the detection and reporting of harmful surface quality deviations such as holes, spots, wrinkles, edge cracks, and coating streaks. Were they to go unreported these defects would not only result in customer complaints and returns, but also potential production problems, including web breaks or damage to the soft calender rolls.
Futec, manufacturer and supplier of 100 per cent automated defect detection systems, says its MaxEye automatic surface inspection system allows defects to be detected in real-time and measures to be taken to avoid expensive damage, lost production and unacceptable waste.
Ray Scragg, of Futec Europe, notes that because the paper web moves so quickly, the real-time detection of defects needs to occur within a matter of milliseconds, so that preventative action can be taken. Such action often involves removing defective sections of the web by diversion or cutting.
On-line calendering is very sensitive to localized overheating of the calendering rolls. Certain coating defects (if not caught in time) can lead to lumps of pigment and other items sticking to the rolls, resulting in overheating and damage. An increasingly important method of avoiding localized overheating and other problems is to inspect the incoming web automatically before it enters the rollers. This inspection must be able to react to defects within a period of around 500ms, leaving just time enough for any reactive mechanical intervention to take place.
The MaxEye is typically installed in a paper machine’s dry end and is generally supplied with Futec monochrome (colour not usually being necessary although colour options are available) line scan cameras, lighting system, encoders, patrol lights and operator console unit with integrated printer. Reject devices and diverters are available as an option.
The system features Futec’s own 4,000 bit line scan cameras, or alternatively 2,000, 1,000 and 500 bit technology. This enables the company to choose the best combination of cameras to suit the required line speed, which may be very high (1,500m/min) and desired resolution. The system has integrated high speed image processing electronics and powerful independent defect detection algorithms. The MaxEye stores jobs for rapid reselection of previously used settings, logging as many as two million defect images for screen display and printed reports.
PC Industries claims its RX300 line of digital defect detection systems provide higher colour resolution and greater picture clarity than comparable systems. They are capable of 100 per cent repeat print defect detection inspection, sampling print defect detection, or programmed positioning with print defect detection. An important feature is the eight-function remote control that needs no on-screen programming or set-up. These systems have been installed on both narrow and wide web presses.
TruRegister is an optional upgrade for the new TG 4000 Series of automatic web inspection systems from TruColor. For automatic register presetting in CI presses, TruRegister uses special printed register targets with each job. Coupled with a data communication link to the press, it automatically sets the colours into the desired registration. It will support jobs up to 12 colours and can begin calculations and corrections after one printed repeat.
The TM-4000CL is a miniature, ultra high resolution 4.2 megapixel monochrome progressive scan camera with dual tap output said to offer a host of high end features.
Available from Firstsight Vision, the interline transfer sensor has a resolution of 2,048 x 2,048 pixels, with a frame rate of up to 15 frames/s giving full vertical and horizontal resolution and high speed shuttered images at up to 1/16,000s, which can be asynchronously reset by external pulse control. It offers built-in look-up table (LUT) and automatic dual channel compensation. Applications include intelligent transportation systems, high definition graphics and gauging.
AVT’s demonstration of a Print- Vision/Helios automatic 100 per cent system on a complete label production line on the HP stand at Labelexpo was the company’s first inspection of digital print. The line composed an HP Indigo ws4000 press and an Omega finishing line. The inspection system was mounted on a table between the press and finishing.
Said HP Indigo marketing manager Europe Danny Dams: “AVT’s product guarantees the most thorough label inspection – both on content and graphical aspects – and can validate out of a PDF file, which is crucial for the pharmaceutical market.” AVT’s vice president marketing and sales said: ” We believe the combined configuration will present opportunities for workflow improvements that will further drive the collaboration between HP and AVT.”
Basler emphasized its recently launched off-line inspection system during ICE. A stand-alone system said to bridge high end machine vision performance at an affordable price, it automates the visual inspection of samples in the laboratory and production. A particular advantage is that it will detect and classify flow lines on clear film, says general manager Dirk Hackenberg. Also capable of detecting defects on opaque material, it features intuitive software with Basler’s Easy Teach integrated classifier. Set-up is done by touchscreen and Easy Teach automatically chooses the best parameters of a defect to assure consistent quality information.
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Erhardt + Leimer
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