Feature Packaging


he use of shrink wrapping offers a number of benefits for automated handling and palletising processes, from cost savings to more attractive branding and improved pack quality. As a consequence, it is now universally employed. However, its use has created a prob- lem which, up until now, has proved perplexing to solve. The challenge is knowing how to achieve 100% effi- ciency in detection of automated bar- code labels - as detecting clear-shiny, dark-glossy or multi-reflective surfaces is a difficult task, especially where there are complex curved shapes or transparent outlines. To help solve the problem, SICK has introduced its MultiPac sensor to eliminate the possibility of false or misleading signals and achieves con- sistent detection in multi-product han- dling applications even when surfaces are shiny, clear or curved.


Achieving error-free detection T


The reliable detection of six packs in PET foil is a real challenge due to its highly reflective and uneven surfaces. Here, Phil Dyas, SICK UK’s industrial sensor product specialist, explains how the company’s new MultiPac sensor provided a solution to the problem at a PepsiCo soft drinks plant in Germany


causing the label to get jammed on the stripper. Both can cause down-time and create unnecessary costs.


The solution


Above: SICK’s new MultiPac sensor has eliminated the possibility of false or misleading signals and achieves highly consistent detection in multi-product handling


In a high speed packaging and labelling operation at a bottling plant, un- or mislabelled packs have to be detected by the human eye or by addi- tional scanners, removed, returned and relabelled. In a competitive high volume market where product cost is low and margins are squeezed, han- dling adds to costs. To maximise the efficiency of the shrink wrap station, many bottling plants will feed through different products with a range of sizes and shapes. The requirement for versatility in shape detection can compound the problem as conventional proximity sensors may have to be constantly and individually adjusted.


applications even when surfaces are shiny, clear or curved


PepsiCo


The effectiveness of the SICK Multipac is demonstrated by the sensors in use on the labelling systems supplied to the PepsiCo filling plant by Logopak Systeme. The detection error rate was reduced to zero throughout a six month period, eliminating a signifi- cant cost for PepsiCo.


PepsiCo Deutschland operates two filling plants in Germany. Its plant at Nieder-Roden, south of Frankfurt, is responsible for the production of soft drinks e.g. for the Pepsi, Punica, Lipton Ice Tea and Schwip Schwap brands. An entirely new filling plant has been commissioned at this works. The full PET bottles are wrapped in foil at the end of the filling line and a label is attached to the six-pack. Logomatic 510 M90 tray labelling systems from Logopak Systeme ensure that every label is reliably positioned on the uneven pack structure and check that the foil is not damaged.


The challenge Left: the


effectiveness of the SICK Multipac is demonstrated by the sensors in use on the labelling systems supplied to the PepsiCo filling plant in Germany


The labelling process is triggered by a photoelectric proximity switch whose detection task is very demanding - the sensor must reliably detect the pack in a particular position and must not ‘lose’ the light reflected back from the pack while the six-pack is in front of the proximity switch. However, the shiny and uneven sur- face can lead to random and unman- ageable reflections, which cause conventional standard proximity switches, with a single receiver system, to reach their limits very quickly because they lose ‘sight’ of the object due to a deflection of the trans- mitted light. This results in an inter- ruption of the signal, prompting the labelling system control to initiate a second label for the same pack, or


22


The SICK Multipac sensor provides reli- ability that would have previously been impossible. The sensor has two inde- pendent receiver systems. They can offset the brief deflections caused by the uneven pack surface because at least one of the two receivers always captures the reflected light. Additionally, a high power LED emits high intensity light so that even faint reflective surfaces are reliably detected.


Each receiver system comprises sev- eral elements which facilitate a differen- tiated signal assessment and deliver a more refined result to the common signal processor. Having just two receivers also facilitates SICK’s proprietary ASIC evalu- ation algorithm, otherwise much greater (and more costly) processing perfor- mance would be required to coordinate the two receiver systems. To ensure sufficient light being reflected back to the receivers, the MultiPac benefits from SICK’s PinPoint LED. PinPoint produces a tightly focused spot, without the central unlit portion that characterises earlier LED emitters. With this performance, sufficient light is received to detect a very wide range of different sizes of film wrapped bottle packs on the same packing line.


System integration Multipac’s integration into, for exam- ple, a conveyor system, or as at PepsiCo, as part of the labelling system, is also convincing.


Thanks to a scanning distance of up to 500mm the Multipac enables maximum freedom in positioning and installation, and does not require a reflector. There is therefore, no need to adjust the mount- ing height when different size packs are put on the shrink wrapping line. Since the Multipac’s commissioning in 2011 there have been no problems in pack detection. It has achieved detec- tion reliability that was previously impossible and PepsiCo has profited from a smooth process during pack transport to the palletising station.


SICK www.sick.co.uk T: 01727 831 121


Enter 208 MAY 2013 Automation


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