Evaluating Fitness to Takt Time (FiTT) in a manufacturing environment: case studies

Abstract

Purpose This study aims to address a key limitation of the widely used overall equipment effectiveness (OEE) metric, its disconnection with customer demand, which can lead to overproduction. This paper applies and evaluates a novel metric, Fitness to Takt Time (FiTT), designed to align production with customer demand and operational variability, thereby supporting lean manufacturing objectives. Design/methodology/approach FiTT integrates Takt Time and a variability tolerance factor (α) into the traditional OEE structure. The study employs two real-world case studies, Alamo Sheet Metal and Ruelco Inc., to demonstrate the practical implementation of FiTT. Data on machine performance, production rates and demand alignment were collected and analyzed over multiple production cycles. Findings The results indicate that FiTT offers a more balanced performance assessment by discouraging overproduction and underproduction. Compared to OEE, FiTT provided clearer signals for aligning production with actual customer demand, and it supported improved managerial decision-making. In both cases, FiTT enabled operational improvements without sacrificing efficiency or quality. Research limitations/implications FiTT currently applies to individual machines or processes and does not account for system-level interdependencies. Future research should explore how FiTT could be scaled to evaluate entire production lines. In addition, the variability tolerance factor (α) is currently chosen heuristically. Developing a scientific method to define a based on operational risk or stochastic variability remains a valuable direction. Finally, this study used two cases from a single industry segment; broader validation across sectors and geographies is recommended. Practical implications FiTT enables practitioners to monitor production in relation to actual demand, supporting leaner operations, reduced inventory build-up and improved working capital. Managers can use FiTT to detect overproduction risks that OEE overlooks, guiding more effective scheduling and resourcing decisions. This aligns daily operations with broader lean goals. Social implications By promoting demand-driven production, FiTT helps reduce excess energy use, material waste and unnecessary labor. This supports sustainability goals and enhances corporate environmental responsibility. In Industry 4.0 contexts, FiTT enables agile, customer-focused production that minimizes resource consumption and aligns with social expectations for greener operations. Originality/value To the best of the authors’ knowledge, this is the first empirical study to apply FiTT in real manufacturing settings. It extends the original conceptual framework by providing practical insights, validated results and the potential to integrate with Industry 4.0 systems. The findings contribute to lean performance measurement literature by introducing a demand-driven metric that enhances responsiveness and reduces waste.