PETINAR PETplanet Insider Vol. 23 No. 11/22 www.petpla.net 32 Does size matter? - New challenges for the closure production require new mould solutions As the final highlight of the first day of the PETinar conference, PETplanet has invited, as Ruari aptly remarked, a good friend of PETplanet. Mr Michael Fink, Vice-President of Sales & Marketing from z-moulds came up with an equally remarkable innovation. Michael first presented some facts about the company z-moulds. The company is headquartered in Dornbirn, Austria, with a subsidiary in Atlanta, USA. Its global presence stretches from Canada to Mexico, Brazil to the U.A.E., India and finally China. He continued that z-moulds, as a mould making specialist for caps helps it customers to develop the best design for any cap application. All global testing standards are possible in the approved z-moulds laboratory. After designing, testing, and developing, z-moulds supports the inline work at its customers’ premises. Michael explained the well-known, proven, and patented z-slides technology. It differs from other mould systems in the following aspects: the front of the mould has a complete flat parting line. Centring of the cavities is not necessary. The cavities and sliders are located inside the mould. The mould itself is centred with guiding bars; this results in an almost wearfree system. Each cavity is accessible from the front. The entire cavity stack can easily be pulled out so that each part of the cavity can be replaced (eg. core, cooling top, slider). The 70 mm frame of the mould stays the same for all kind of closures. It is a completely modular system. Also, the cavity pitch remains the same, and in addition the same hot runner system can be used. Michael continued that the z-slides technology is still used but has now been extended. For a tethered cap, for example, the sliders must be higher because the parting line is moving up. By changing the angles on the demoulding face, where the height is increased to 15 mm, it is possible, to produce a 29/25 closure design entirely on the cold half of the mould. The extended z-slide technology can easily be implemented in the existing z-slides system. Michael concluded that all z-moulds technologies like the z-slides, z-slides extended, and the z-folded system are compatible with each other. With such cutting-edge technology, new ground can be broken. Michael asked what can be enhanced for tomorrow and talked about the mould size. He stated that in general the z-slides are known for their compact size because no sidewards movement is necessary. In the future could it be possible for the mould size to be even smaller? He presented two case studies. The first one was a project for a customer where a 23 mm light weight closure has to be produced on a high speed 128 cavity system in less than 2s. The problem today is that existing 128 cavity moulds are very big, and because of that they need big machines (eg. 650 t). From a closure point of view, these big machines are not necessary. As far as the clamping force goes, a 420 t machine would be enough, but the mould is then too big. With a new mould design with a pitch of 55mm the mould fits in a 420 t standard cap machine and this common machine size range allows faster cycles. (Fig.1) Also the weight of the moving part of the moulds is important. With the smaller mould there is a 52% weight saving which in turn reduces the overall cycle time. The reduction in cycle time results from the falling distance being cut to 300mm, leading to a saving of 0.07s. falling time per shot. Michael concluded by saying that with a new frame a smaller machine range can be used. Mouldhandling is much easier and the reduction in cycle times can be achieved due to the lighter weight and height of the mould. And finally, the less weight that needs to be moved leads to an enormous energy saving. The second case study focuses on a 96-cavity moulding system running in a 420 t machine. Fig 2: New 55mm pitch z- slides: size: 596 x 896 x 650mm, weight: ES 1,480 kg / NS 1,290 kg Pitch Fall height Falling time Competition 1,200 mm 0.495 s 70mm 1,000 mm 0.452 s 55mm 700 mm 0.378 s Total saving of falling time 0.117 s Pitch Es weight Open/close time Competition 2,690 kg 0.84 s 70mm 2,300 kg 0.81 s 55mm 1,480 kg 0.76 s Total saving of open/close time 0.08 s Some new closure designs require less clamping force, and consequently, a 250 t machine would be enough. As in the first example the size of the mould is too big. With the new z-slides pitch of 55mm the fall height is reduced, resulting in less falling time; the weight of the mould is reduced which leads to a more rapid opening and closing time, resulting in a lower energy consumption. (Fig.2) The answer to the question ‘does size matter?’ seems clear: energy savings, fast cycle times, a smaller machine are important parameters on which purchasing decisions are made! www.z-moulds.com We thank all speakers and participants as well as our sponsors! We would like to point out that the lectures as well as the presentations are available online at: https://petpla.net/2022/09/06/ review-technical-highlights-drinktec2022/?s= Fig. 1 The new 55mm pitch fits with 128 cavities into standard 420 t cap machines. Sponsors
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