A Heuristic Framework for Stock Allocation in Vertical Lift Modules for Make-to-Order Production Warehousing

This paper investigates the role of vertical lift modules (VLMs) as automated storage and retrieval systems in modern internal logistics, with an emphasis on their quantitative performance dimensions. The analysis integrates throughput models, storage assignment methods, and simulation-based evaluations to examine how VLM configurations influence efficiency, capacity, and cost. Drawing on a synthesis of analytical models and empirical findings, the research quantifies order-picking times, retrieval cycles, and machine utilization under varying operational conditions. Key aspects include the optimization of slotting and batching strategies, the evaluation of dual-bay versus single-bay performance, and sensitivity analyses of travel distances and waiting times. Comparative cost–benefit models are applied to assess productivity trade-offs between VLMs and traditional storage systems, identifying critical thresholds where automation yields measurable economic advantages. The framework is further applied to a case of VLM adoption in the HVAC industry, within warehousing operations characterized by high product variety, where a stepwise methodology for seamless implementation is proposed. The guiding criteria for this methodology are based on technical and practical feasibility as well as economic viability. The investigative process combines a structured literature review, model-based scenario evaluation, and performance indicator benchmarking to establish a robust framework for decision-making. The results highlight the importance of integrating quantitative tools with insights from practical cases, advancing knowledge for both academia and practitioners, and providing guidelines for enhancing operational efficiency.