PETpla.net Insider 09 / 2017

BOTTLE MAKING 34 PET planet Insider Vol. 18 No. 09/17 www.petpla.net Please order your copy at the PETplanet Insider book shop: www.petpla.net/book3 Stretch Blow Molding Second Edition by Ottmar Brandau € 130,00 320 pages © Copyright Elsevier 2012 product development caps & closures design high cavitation moulds multi-component moulds closure production systems after sales service competent – professional – inspiring Hoechster Strasse 8 | 6850 Dornbirn | Austria | www.z-moulds.com drinktec 2017 September 11th-15th meet us at booth A4.417 Moulds at Drinktec Cap 29/25mm 3-start water @Arburg in A4.323 Cap 38mm 3-start aseptic @Netstal in A4.321 Cap 26mm water @Sumitomo Demag in A4.123 At the end of the oven track, preforms enter a star wheel or other transfer device and are moved one by one onto the blowing wheel posi- tion #1. The machine described has 18 blow cavities (position #3). Each cavity has its own blow mould, stretch rod, water connection, and three blowing valves for pre-blow, blow, and exhaust. Air and water connections as well as electrical lines for sensors and switches come from a feeding unit located in the centre of the blow- ing wheel. These central distributors are one of the reasons that rotary machines are more expensive com- pared to linear machines of the same capacity. Figure 3.16 One of the two blow-mould halves with bottle and bottom insert. Photo courtesy of KHS Corpoplast. Blown bottles leave the mould via grippers or star wheels onto conveyors at position #11 (see Figs 3.16 and 3.17). These grippers are very different from the ones used on linear machines and transfer preforms between ovens and blow moulds and bottles between blow moulds and discharge unit. They are cam-controlled and rotate on shaped tracks. Instead of having cylinders that open and close them, they are actually just pushed and pulled into and from pre- forms that are securely held in star wheel pockets or the blow moulds in the case of finished bottles. This saves time and maintenance. However, it does require a particular preform neck design. Figure 3.17 One of many gripper designs. Diagram courtesy of KHS Corpoplast. To facilitate the handshake between star wheel and gripper, there must be room for the gripper to engage the pre- form above the transfer ring as the pre- form is hanging from it in the star wheel (Fig. 3.18). This requires the preform to have a straight section underneath the thread beads for the gripper and another section underneath the transfer ring for the star wheel. Figure 3.18 During handshakes between various parts of the machine the area on to and underneath, the transfer ring is used for grippers. Brand owners in industries such as cosmetics may find transfer rings unappealing for their customers and it is possible to run preforms with- out a transfer ring through an RSBM machine, albeit at a slower speed. High-speed machines generally use air conveyors where bottles hang from their neck support ring, gently pushed by air blowers. Anti-slip agents in the resin help reduce any friction in the conveyor lines.