Transient Characterization of Single Screw Plastic Extrusion Process: The Internal Model Control Design Approach

This study presents an optimized Internal Model Control (IMC) design for transient response enhancement in single-screw plastic extrusion, addressing critical industry challenges in product quality and process efficiency. Initial system performance exhibited suboptimal metrics (2.15% overshoot, 12.8 s settling time, 5.64 s rise time), unsuitable for precision manufacturing. Through MATLAB-based implementation, the proposed IMC controller achieved zero overshoot, a 0.336 s rise time, and 0.583 s settling time – outperforming conventional PID and digital compensators by 82.9–100% in key performance indicators. A systematic evaluation of controller orders (1st – 3rd) and time constants (0.1 – 1.0) revealed the superiority of 2nd/3rd-order IMC, demonstrating 94% faster settling and 100% overshoot elimination compared to prior work [8]. The design incorporated robust tuning parameters (τ = 0.1 s) validated under real-world variability (±5% screw speed fluctuations, ±8% material property changes), ensuring industrial applicability. Novel transient characterization of extrusion dynamics during startup and material transitions, scalable control framework requiring no retuning across polymer grades (PP, HDPE, ABS) and energy savings (12 – 18%) and scrap reduction (25 – 40%) through optimized dynamics were the key contributions as well as simplified tuning via MATLAB. The study bridges theoretical control theory with practical implementation, offering a replicable template for extrusion process optimization.