Multi-Case Simulation-Based Scalability Validation of Parallel Assembly Sequence Planning for Sustainable Manufacturing of Large-Scale Wind-Turbine Gearboxes and Complex Products

Efficient assembly planning is increasingly recognized as an important enabler of sustainable manufacturing because it decreases production duration, rework, resource consumption, and operational waste. The assembly of large-scale wind-turbine gearboxes and complex products is characterized by high part counts, heavy and tolerance-critical parts, intricate priority constraints, and significant opportunities for parallel-task execution. This paper presents a multi-case simulation-based experimental performance and scalability validation of these complex products. A scaling-based simulation technique was developed, applying assembly graph parameters, number of tasks, priority edges, integration nodes, priority density, handling complexity, and error risk. The 10 MW wind-turbine gearbox was applied as the calibration baseline and twelve benchmark cases were simulated using Monte-Carlo uncertainty propagation. Outcomes demonstrate that the proposed PASP framework scales consistently across product families, with time decrease fluctuating from 20.4% to 30.3%, cost reductions fluctuating from 9.4% to 18.0%, and quality indices improving from baseline values of 0.87–0.94 to enhanced values of 0.91–0.965. Error decrease remained mainly strong in large wind-turbine assemblies, attaining 85–92% in offshore, hub-pitch, nacelle, generator, and gearbox cases. These outcomes validate the fact that the proposed PASP components are transferable, scalable, and appropriate for sustainable Industry 4.0 complex assembly line systems where cost control, quality, reliability, and productivity must be augmented, simultaneously.