Bielenberg Christian, Stommel Markus, Karlinger Peter
Department of Plastics Technology, Faculty of Engineering Sciences, Rosenheim Technical University of Applied Sciences, Hochschulstraße 1, 83024 Rosenheim, Germany.
Faculty of Mechanical Science and Engineering, TUD Dresden University of Technology, Helmholtzstr. 10, 01062 Dresden, Germany.
Polymers (Basel). 2025 Apr 18;17(8):1096. doi: 10.3390/polym17081096.
Thermoplastic injection molding is a widely used process for producing complex three-dimensional plastic parts with tight dimensional tolerances. A key determinant of part quality is the switchover point-the transition from velocity-controlled filling to pressure-controlled packing. This transition affects critical product attributes, such as d imensional accuracy, weight consistency, and surface finish. Precise control of the switchover point enhances process stability, robustness, and adaptability. This review consolidates recent advancements in switchover methods and adaptive control techniques. Improvements in traditional methods include the use of pressure gradient detection to mitigate viscosity variations and adaptive control to refine stroke- and time-dependent switchovers. In addition, deformation-based strategies detect the mold-opening force associated with cavity pressure through clamping force, mold separation, or tie-bar elongation. The integration of machine learning and feature extraction techniques enables the real-time adjustment of the switchover point by mapping relationships between process parameters and quality criteria. In addition, ultrasonic sensors provide non-invasive melt front detection, reducing the risk of mold damage. Real-time simulations, updated through nozzle pressure feedback, complement these methods to achieve precise switchover timing. This review also identifies persistent challenges, such as sensitivity to material properties, machine wear, and environmental conditions, and it explores future directions for improving the accuracy and adaptability of switchover control in modern injection molding processes.
热塑性注塑成型是一种广泛应用的工艺，用于生产具有严格尺寸公差的复杂三维塑料零件。零件质量的一个关键决定因素是切换点——从速度控制的填充到压力控制的保压的转变。这种转变会影响关键产品属性，如尺寸精度、重量一致性和表面光洁度。对切换点的精确控制可提高工艺稳定性、稳健性和适应性。本综述总结了切换方法和自适应控制技术的最新进展。传统方法的改进包括使用压力梯度检测来减轻粘度变化，以及使用自适应控制来优化与行程和时间相关的切换。此外，基于变形的策略通过夹紧力、模具分离或拉杆伸长来检测与型腔压力相关的开模力。机器学习和特征提取技术的整合通过映射工艺参数和质量标准之间的关系，实现了切换点的实时调整。此外，超声波传感器可提供非侵入式熔体前沿检测，降低模具损坏风险。通过喷嘴压力反馈进行更新的实时模拟补充了这些方法，以实现精确的切换时机。本综述还指出了持续存在的挑战，如对材料特性、机器磨损和环境条件的敏感性，并探讨了在现代注塑成型工艺中提高切换控制精度和适应性的未来方向。
