Cross phase process concepts for injection moulding using modern control strategies

• Applicants: Professor Dr.-Ing. Christian Hopmann; Dr.-Ing. Sebastian Stemmler, since 10/2024
• Subject Area: Plastics Engineering
• Term: from 2017 to 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 378417139

• Final Report Year: 2025

Final Report Abstract

Injection moulding is a highly automated process for the production of plastic parts. Traditional process control strategies involve switching between two different control variables in the injection and holding phase respectively. The switchover point and other machine settings are determined as part of an often complex process setup in order to achieve the most reproducible and economical production of the required part quality. Incorrectly configured processes result in incomplete component filling or overmoulding. Part quality is also negatively affected by process variations due to changes in e.g. ambient conditions. When processing post-consumer recyclates (PCR), considerable differences in the composition and history of the material batches result in deviations in the process trajecaories and consequently in the part quality. The switching problem can be solved by the phase-combining process control strategy developed in the first project phase. For this purpose, a model-predictive cavity pressure control is used, which regulates the cavity pressure over the entire process duration thus enabling a high reproducibility of the process and the part quality. The setting effort is further reduced by automated optimization routines. Quality losses due to PCR batch fluctuations can be minimized by means of the extended control framework developed during the second project phase. As part of the project, a replication of the part quality based on an improved model-predictive cavity pressure control and layered reference optimization using Bayesian Optimization was successfully demonstrated for various PCR batches and components. The achieved reproducibility of process and part quality surpasses conventional process control in plastic injection moulding.

Link to the final report

https://doi.org/10.18154/RWTH-2025-10868

Publications

• Cross-phase Model-based Predictive Cavity Pressure Control in Injection Molding, Proceedings of the 3rd IEEE Conference on Control Technology and Applications (CCTA 2019). Hong Kong, China, 2019
  S. Stemmler; M. Ay; M. Vukovic; D. Abel; J. Heinisch & C. Hopmann
  
• Die Umschaltproblematik und ihre Folgen, Kunststoffe 110 (2020) 4, S. 82-86
  C. Hopmann & K. Hornberg
  
• Intelligente Regelungsstrategien als Schlüsseltechnologie selbstoptimierender Fertigungssysteme. RWTH Aachen, Dissertation
  S. Stemmler
  
• Precise, reproducible process control for injection moulding. Umdruck zum 30. Int. Kolloquium Kunststofftechnik. Aachen, 2020
  C. Hopmann; S. Schnerr; M. Schirmer; R. Vaculic; P. Liedl; H. Dornebusch; K. Horberg; M. Vukovic & D. Abel
  
• The Switchover Problem and ist Consequences, Kunststoffe international 02 (2020), S. 40-44
  C. Hopmann & K. Hornberg
  
• Adaptive modellbasierte Regelungskonzepte als Basis für den selbsteinstellenden phasenübergreifenden Kunststoffspritzgießprozess. VDI Automation 2021, Baden Baden, 2021
  M. Vukovic; S. Stemmler; D. Abel; K. Hornberg & C. Hopmann
  
• Auswirkungen zyklischer Prozesseinflüsse auf den Werkzeuginnendruckverlauf und die Bauteilqualität im Spritzgießprozess. Zeitschrift Kunststofftechnik, 1, 179-203.
  Hornberg, Katharina
  
• A Comparison of Two Sigma Point Kalman Filters for Adaptive Cross-phase Cavity Pressure Control in Injection Molding, 10th IFAC Conference on Manufacturing Modelling, Management and Control, Nantes, Frankreich, 2022
  M. Vukovic; S. Stemmler; D. Abel; K. Hornberg & C. Hopmann
  
• Adaptive model-based predictive control for cross-phase cavity pressure control in injection molding. Journal of Manufacturing Processes, 77, 730-742.
  Vukovic, Marko; Stemmler, Sebastian; Hornberg, Katharina; Abel, Dirk & Hopmann, Christian
  
• Increased process stability in the injection moulding of post-consumer recyclates using cavity pressure for process control. Umdruck zum 31. Int. Kolloquium Kunststofftechnik. Aachen, 2022
  C. Hopmann & K. Hornberg
  
• Part Quality Control through Holistic Consideration of Cross-phase Cavity Pressure Characteristics in Injection Moulding. 2nd International Symposium on Plastics Technology, Institut für Kunststoffverarbeitung, 2022
  K. Hornberg; C. Hopmann; M. Vukovic & D. Abel
  
• Compensation of Batch Fluctuations of Post-Consumer Recyclate in Injection Molding by Phase Unifying Process Control. Annual Technical Conference - ANTEC, Conference Proceedings. Denver, USA, 2023
  K. Hornberg; C. Hopmann; M. Vukovic; S. Stemmler & Abel, D.
  
• Precise Process Control with InjectiX - Phase-Unifying Cavity Pressure Control for PCR Processing, Kunststoffe international 3 (2023), S. 36-39
  K. Hornberg; M. Vukovic; J. Gerads; Y. Lockner; C. Zimmermann; M. Schmitz; S. Stemmler; C. Hopmann & D. Abel
  
• Präzise Prozessführung mit InjectiX - Phasenvereinende Werkzeuginnendruckregelung bei der Verarbeitung von PCR, Kunststoffe 3 (2023), S. 70-73
  K. Hornberg; M. Vukovic; J. Gerads; Y. Lockner; C. Zimmermann; M. Schmitz; S. Stemmler; C. Hopmann & D. Abel
  
• Automated controller set-up for model predictive cavity pressure control. Umdruck zum 32. Int. Kolloquium Kunststofftechnik. Aachen, 2024
  C. Hopmann; K. Hornberg; D. Abel; M. Vukovic & S. Stemmler
  
• Phasenübergreifende Prozessführung für das Thermoplast-Spritzgießen, RWTH Aachen, Dissertation
  M. Vukovic
  
• Phasenübergreifende Regelung des Werkzeuginnendrucks zur Erhöhung der Reproduzierbarkeit im Spritzgießen, RWTH Aachen, Dissertation
  K. Hornberg