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3/9/2020 | 2 MINUTE READ

Injection: Updated All-Electric Machine Series Targets Cap Production

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Engel has updated its e-cap line of all-electric machines promising more speed and efficiency, including sub 2-sec cycles.

Injection molding machine and automation supplier Engel is updating its e-cap line of all-electric machines that target closure molding. Originally launched at K 2010, the new e-cap series will feature four sizes—220, 280, 380 and 420—with clamping forces from 2200 to 4,200 kN (about 22 to 472 tons). Two different ejector drive technologies are available, with hydraulic ejectors as standard. Optional servo-electric drives use around 10 percent less energy.

To demonstrate the machine’s capabilities, Engel set up a 2440/380 press molding 29/25 caps from a 96-cavity mold from Plastisud. With a shot weight of 1.3 grams per cavity, the machine achieved a cycle time of less than 2 seconds, running an HDPE from Borealis/Borouge. The cell includes 100 percent quality inspection with an IMDvista camera system and a dry air system by Eisbär.

Engel e-cap

Closures, including for still water, are getting lighter and lighter with some dropping below a single gram.

Engel said the e-cap was updated in response to new demand requirements from the market, with still water caps now weighing less than a gram, while cycle times have dropped from 2.5 seconds in 2010 to 2 seconds or less today. To make this possible, the new e-cap offers faster mold opening and closing movements and a more stable machine bed for more frequent load cycles. That stability is enhanced further by the reinforced frame and mold mounting platens.

The e-cap 380 has a dry cycle time of 1.3 seconds thanks in part to parallel movements for ejection and mold opening. The ability to amplify ejectors on demand via a switchable hydraulic booster is new. This applies to situations where the machine has stopped and the ejectors have to apply more force to remove caps that have cooled down in the mold. Engel points out that since production interruptions are rare, it was more efficient to use servo-hydraulic drive amplification than to equip the machine with more powerful, but rarely necessary, ejector drives.

Engel notes that it completely redesigned the e-cap’s plasticizing unit to handle preferred cap materials, including HDPE grades with a melt flow index (MFI) of between 0.8 and 1.4 g/10 min. To achieve fast cycles, high plasticizing rates are required, which lead Engel to increase the plasticizing drive’s torque and create a new plasticizing screw and wear-resistant sliding ring non-return valve specified for cap molding. Engel says the barrier screw design allows the machine to process high viscosity HDPE in a gentle way. Braking energy is recuperated, increasing energy efficiency. Engel says the e-cap 380, has specific energy consumption of 0.37 kWh per kilogram of pellets processed.

Engel e-cap

With short cycle times of less than two seconds, Engel says the new e-cap ensures very high precision and repeatability.