CAPS & CLOSURES 28 PETplanet Insider Vol. 23 No. 01+02/22 www.petpla.net iQ weight control for caps & closures Boosting process stability Authors: DI Christoph Lhota, Vice President Packaging at Engel, DI Karlheinz Mayr, Head of smart machine Development at Engel Quality control is good, but a stable process is even better. An unchanging process may not be a guarantee, but it is both an indicator and a prerequisite for consistent part quality. Smart assistance systems contribute to this. For example, iQ weight control by Engel, which is used worldwide in the manufacture of technical parts and automotive components, among others. In addition, significant quality improvements are now also achieved in highperformance applications with very short cycle times. Fluctuations in ambient conditions and raw material change the flow properties of the plastic melt during injection and can impact on the quality of the moulded parts. In the worst case, the result is rejects, and this can quickly become very expensive in the manufacture of caps & closures with extremely short cycle times and very high cavity counts. Smart assistance systems which continuously analyse and automatically adjust qualitycritical parameters open up huge potential, even in high-performance applications, as Engel is able to demonstrate based on tests using iQ weight control. Consistent quality In each individual cycle, iQ weight control analyses the pressure and screw position profile in real time during the injection phase and compares the measured values with a reference cycle. On this basis, new process parameters are calculated and process settings are automatically readjusted for the on-going cycle. This closed loop process control influences the speed profile during injection, the switchover point and the holding pressure profile without lengthening the cycle time. In this way, fluctuations in environmental conditions and in the processed material are automatically compensated for. iQ weight control thus ensures a consistently high product quality and reduces rejects to a minimum. Batch changes without process adjustment In order to demonstrate the performance of iQ weight control in high-performance applications, injection moulding tests were carried out with, among others, a 96-cavity mould for 29/25 caps for still water from Plasti-sud. A type MB7541 HDPE by Borealis with an MFI of 12 was processed. The part weight was 1.25g, resulting in a total shot weight of 120g. An all-electric 380-tonne injection moulding machine from the Engel e-cap series was used; Engel developed this machine specifically for caps & closures production. The cycle time of this application is less than 2 seconds with an injection time of less than 0.3 seconds. In order to assess the performance of iQ weight control, targeted process changes were deliberately provoked, among other things by changing the raw material batch several times. The changes resulted in the critical quality characteristics of the caps produced being outside the tolerance range. The injected melt volume, for CAPS & CLOSURES Engel developed the all-electric e-cap machine series specifically for caps & closures production. In the production of 29/25 caps on an Engel e-cap injection moulding machine with a 96-cavity mould, iQ weight control is claimed to more than double process stability. The cycle time (< 2s) doesn’t change.
RkJQdWJsaXNoZXIy NTY0MjI=