PETpla.net Insider 01+02 / 2020

CAPS & CLOSURES 12 PET planet Insider Vol. 21 No. 01+02/20 www.petpla.net New control algorithm for higher outputs High performance for production of closures The Netstal Elion series has been developed further specifically for the beverage cap seg- ment and is now equipped with new, user-specific features. The basic hybrid drive concept of the Elion was maintained: The centrally positioned 5-point dual toggle lever with horizon- tal servo motor is still being used because it moves dynamically, harmonically and quickly. Bucking the trend that moves toward all-electric machines, Netstal continues to prefer the hybrid approach with a combination of electric and hydraulic axles for beverage closures. CAPS & CLOSURES High performance, low energy consumption “We are relying on our hybrid injection units for the quick and pre- cise production of closures because that way we don’t have to sacrifice performance,” emphasised Peter Schmid, the applications team leader of KraussMaffei HighPerformance AG in Näfels, Switzerland. For this reason, Netstal machines never use spindle drives. By consistently using hydraulic cylinders, Netstal ensures that the machine will deliver an optimal performance – while being operated efficiently at the same time. Netstal Elion machines with a hybrid drive concept also feature competitive energy consumption. The company states that at their upper performance limit energy values are as low as those of a comparable all-electric machine. The key factors are the efficiency of the clamping unit and the recuperation of energy, which is temporarily stored as hydraulic energy and then fed back into the system. This is something that could not be accomplished with spindle drives because, for geometric reasons, they are subject to a self-locking effect and therefore do not feature the optimal concept with regard to dynamics, effi- ciency and wear. New control algorithm allows higher outputs By adapting the clamping unit con- troller, a significant optimisation of the dry cycle times of the Elion has been achieved. Depending on the model, the dry cycle was shortened by up to 0.2 s. The optimisation applies to all Netstal Elion models with Axos ver- sion 8.2.0. and up. This release incor- porates the latest control technology insights. The additional speed is made possible through the adaptive optimi- sation of the acceleration and decel- eration ramps for the clamping unit drive. The maximum moving speed is reached faster and can be maintained longer before the moving mould plate is harmoniously decelerated and the toggle lever mechanism seamlessly transitions to building up the clamp- ing force. This does not compro- mise the mould protection. A shorter dry-running time does not automati- cally mean a faster cycle under real production conditions. That is why the new control algorithm takes into account the potential mould weight and incorporates it in the control of the acceleration and deceleration process. “This allows our customers to further speed up their production cycles and achieve further productiv- ity increases,” explained Schmid. For example: A Netstal Elion 4200 with a 96-cavity mould produces type 29/25 HDPE closures. One closure weighs 1.23 g. Thanks to the optimised con- trol, the cycle can be shortened from 2.77 s to 2.6 s. The hourly output goes up from 124,750 to 132,920 closures, which equals an increase in productiv- ity of 6.5 per cent. New plastics in the production of closures Bimodal and multimodal plas- tics, which are increasingly being used for the production of closures, are another market demand. These materials have various benefits that improve the quality of the closures. They particularly resulted in massive improvements in the area of ESCR. “There are – sometimes large – differ- ences with regard to the flow char- acteristics and the injection process pressures during processing and pro- duction. In addition, there are also sig- nificant differences compared to con- ventional materials with regard to the plasticising performance. These also have to be taken into account when developing applications,” Schmid said. The injection unit was not just adapted mechanically to the new requirements but also with regard to the software. Flexible controls, intuitive operation The freely programmable Axos control technology offers operators high flexibility. An illustrative example was the control circuit which was pre- sented at Drinktec 2017 together with partners. It featured the first integra- tion of external peripheral data in the controller of the injection moulding The electric toggle lever clamping unit of the Netstal Elion with the horizontally arranged servo motor