PETpla.net Insider 04 / 2020

CAPS & CLOSURES 31 PETplanet Insider Vol. 21 No. 04/20 www.petpla.net occurs parallel to the mould opening. What is new is that the direct-drive servo-electric ejectors can be ampli- fied by a switchable hydraulic booster on demand. With the two different drive types, Engel claims to ensure that the machine operates with the best possible efficiency both during running produc- tion and during start-up after a produc- tion interruption. While the caps are not yet com- pletely cooled and very easy to demould during ejection in ongoing production, the ejectors have to apply more force in stop situations to remove caps that have already cooled down in the mould. Since production interrup- tions are rare, it is more efficient to use servo-hydraulic drive amplification than to generally equip the machine with more powerful ejector drives. More powerful plasticising unit for poor-flowing HDPE The plasticising unit was com- pletely redesigned in the course of the e-cap’s further development, as the properties of the materials to be pro- cessed have also changed. The raw material manufacturers have adapted the materials to the lower cap weights. For CSD (carbonated soft drink) caps, the melt flow index (MFI) of today’s HDPE grades is between 0.8 and 1.4 g per 10min. With very short cycle times, these values require particu- larly high plasticising rates. Engel has increased the torque of the plasticising drive accordingly and developed both a new plasticising screw and a new highly wear-resistant sliding ring non-return valve specifi- cally for cap manufacture. Both products are part of the standard scope of supply of the new e-cap machines. With its new design, the barrier screw processes high vis- cosity HDPE in a particularly gentle way, even given high throughput levels, while ensuring a good melt- ing rate and homogeneity of the melt. This further contributes to the high process stability and repeatability of e-cap machines. Optimising energy consumption Cleanliness and energy efficiency have been an essential focus of the series right from the outset. With an encapsulated toggle lever and a clean linear guide of the moving platen, the e-cap machines reliably meet the requirements of strictly regulated production in the food industry. The machines’ all-electric drive technol- ogy makes a major contribution to the energy efficiency. In addition, braking energy is recuperated, reliably pre- venting the need for expensive peak power. Thanks to the efficiency of the drives used, the e-cap machines also only require a minimum of coolant. The e-cap 380, for example, operates at high speed with an energy consump- tion of 0.37kWh per kilogram of pellets. The new e-cap is available in the sizes 220, 280, 380 and 420 with clamping forces from 2,200 to 4,200 kN. www.engelglobal.com l l textile packaging