The next generation of Engel’s all-electric e-cap injection moulding machine series for beverage caps has been launched with a focus on performance and stability.
The original e-cap series was launched in 2010 and since then the requirements for beverage caps have changed substantially, with continuous part weight reductions playing a central role. For example, still water caps with a weight of significantly less than one gram are being produced today, which has led to a drop in cooling and cycle times. Whereas cycle times ten years ago were still 2.5 seconds, today’s machines need to be able to produce at 2-second intervals and faster.
Engel’s new e-cap achieves even faster mould opening and closing movements, and is designed with an even more stable machine bed for more frequent load cycles.
The machinery maker demonstrated the e-cap 2440/380 at a recent in-house event producing 29/25 caps in a 96-cavity mould by Plastisud. The shot weight was 1.3g per cavity with a cycle time of less than two seconds, processing HDPE from Borealis/Borouge. The system is equipped with camera-supported 100 per cent quality inspection by IMDvista and a dry air system by Eisbär. Further system partners are Piovan, PackSys Global and PSG.
Ejection occurs parallel to the mould opening and here Engel has enabled amplification of the ejectors by a switchable hydraulic booster on demand. This ensures maximum efficiency both during running production and during start-up after a production interruption. While the caps are not yet completely cooled and very easy to demould during ejection in on-going production, the ejectors have to apply more force in stop situations to remove caps that have already cooled down in the mould. Since production interruptions are rare, it is more efficient to use servo-hydraulic drive amplification than to equip the machine with more powerful ejector drives for general use. The new series also has a completely redesigned plasticising unit in order to adapt to lower cap weights. For carbonated soft drink caps, the melt flow index (MFI) of today’s HDPE grades is between 0.8 and 1.4g/10 min. Very short cycle times require particularly high plasticising rates.
Alongside the all-electric drive technology, braking energy is recuperated in order to prevent the need for expensive peak power. The e-cap 380, for example, operates at high-speed with a specific energy consumption of 0.37 kWh per kilogram of pellets processed.