Machine Vision & Web Inspection Label inspection at 350 metres per minute

The latest generation of fleyeVision inspection modules used on the Omega SRI processing machines from AB Graphic allows label triggering without the need for an additional sensor, thanks to a collaborative development between Stemmer Imagingand AB Graphic


his makes fleyeVision more cost-effective and

easier to integrate. The modules allow label checking with 100 per cent reliability at speeds of up to 350 metres per minute. AB Graphic produces high

performance systems to inspect labels or other web printed materials. The Omega SRI is a powerful, efficient and versatile label finishing system, which offers three high-speed functions: slitting, rewinding and inspection. The main task of the machine is to cut the incoming strands and rewind them onto individual rolls, because the further processing generally requires single label webs. The machine is capable of handling tape widths from 210 to 1,200mm as standard and is set apart by its ability to include fully integrated ‘fleyeVision’ inspection systems, which can detect missing labels, splice points, matrix residues, label damage, ink residues and dirt spots amongst other things. An estimated 80 per cent of the label machines manufactured by AB Graphic in the UK contain one or even two of the fleyeVision modules, which are manufactured in Germany. The system can also have integrated printers, which add sequential batch numbers or individual details to pre-printed labels.

100 PER CENT INSPECTION ESSENTIAL 100 per cent label inspection is necessary because the label manufacturer may face extremely high compensation claims if, for

labels is also possible if necessary for special requirements. Stemmer Imaging has also supplied the majority of the imaging hardware for fleyeVison modules such as cameras, image capture cards/frame grabbers, lenses, lighting and cables, since 2004 and has provided continuous lifecycle management advice. Components have been updated over this period as requirements for speed, resolution and data throughput have increased. The fleyeVision systems feature colour or

example, products have to be returned as a result of faulty labelling. It can also be very expensive if production processes, for example in bottling plants, come to a standstill due to faulty labels. In the case of pharmaceutical products, the consequences may be even graver, as patients could be put at risk if faulty labels are used on medicines. Modular extension options are available for the fleyeVision system in order to allow the inexpensive, tailor-made configuration of inspection systems in accordance with the customer's requirements. Although designed to be a stand-alone system, it is also simple to retrofit to any printing press or assembly/packaging machine, regardless of the manufacturer. Integration into both digital and conventional processes is possible.

LABEL DETECTION In the latest versions of fleyeVision, the images are processed using a Visual Applets powered FPGA frame grabber with integrated hardware processing so that label triggering can be done without using an additional sensor. This approach was developed in close cooperation between the machine vision experts at AB Graphic and the development team at Stemmer Imaging. In addition to making the vision system easier to integrate, this capability also considerably eases the use of the inspection system for the machine operator. It simplifies and accelerates the setup of new labels, in particular with larger tape widths, makes mechanical adjustments unnecessary and allows the automatic teaching of new labels within a few minutes. However, manual teaching of

monochrome line scan cameras and lenses with a choice of 1k, 2k or 8k resolution, together with suitable line lighting, including UV lighting for the inspection of films. The operating software, developed internally by AB Graphic, enables extremely fast automatic or manual setup of new labels. Due to the tight installation space for the vision system, the optical axis inside the compact housing has been extended by means of a mirror system in order to achieve the required working distance for the line scan cameras.

OUTSTANDING PERFORMANCE Depending on the width of the tape to be inspected, speeds of up to 350metres per minute are possible with the detection of faults down to a size of 0.02 mm². For the reliable recognition of barcodes, the smallest detectable distance between two lines or the smallest resolvable line width is critical. Using an 8k line scan camera on a web width of 210mm, the current limit is 0.08mm. Modules are available which can: measure gaps, compare labels to a PDF master image, verify codes and numbers, check colours, map faults and document findings to meet individual requirements. For added versatility, two-camera versions

of fleyeVision are also available. These allow the front and rear sides of label tapes to be checked or allow the resolution to be increased for large tape widths. Even with this configuration, the system is capable of handling the additional image data produced. Data from both cameras is captured and processed by a single Silicon Software frame grabber, illustrating the importance of good system design from the outset. 

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