PETpla.net Insider 09 / 2010

PREFORM PRODUCTION 24 PET planet insider Vol. 11 No. 09/10 www.petpla.net Fig. 1 and 2: Fan-like formation blockades Unblocking PET conveying One of the leading causes of stoppages on PET conveyor lines is nothing to do with faults in the system or failures in filling; it is to do with the nature of the PET material itself. A new spray- on anti-friction coating system, developed by Steidle GmbH, is claimed to overcome bottle blockages, promote smooth operation, increase operators’ flexibility and to save costs. The cause of fan-like blockage formations (figs 1-2) can be found in the affected PET bottles themselves. The ‘bluntness’ of their surface quality when they leave the stretch blow- moulding machines leads to friction at the contact area between the bottles. Because of this, the bottles cannot rotate freely around their longitudi- nal axes on the transport conveyor, which, in turn, causes a forced rota- tion (fig 3). The result is blockages in transport, especially in curves, ascents and at the end of down- grades. Certain bottle designs can make the situation worse (fig 4). Precoating preforms One solution to this has been known and used for a number of years. Precoating the surface of the PET preforms with an ultra-thin sliding film allows the bottles to rotate against Fig. 3: Friction-forced contrary direction of rotation Fig. 4: Blockages in PET container transport are often caused by forced rotation of the bottles. Certain bottle designs can make the situation worse. Favourable (left) and unfavourable (right) bottle design. each other freely, thus minimising or even completely eliminating fan-like blockages of packaging and bottles during transportation and allowing smoother conveying. Hitherto, such coatings have been available as an option to be applied to preforms, during their manufacture. German company Steidle GmbH has been manufacturing such systems for years; it has devel- oped a new system, called Process Integrated Coating (PIC).