Standard Time Analysis and Ergonomic Improvements for Automotive Body Trim Cell Operations Using MODAPTS

Objective: This study aims to analyze the standard time of a body trim assembly work cell in a cellular layout using MODAPTS and to propose ergonomic improvements for units with high non-value added element ratios.<br/>Background: Cellular layouts are widely applied in smart manufacturing environments as they enable multiple operations to be performed within a single cell, minimizing work-to-work movement and increasing flexibility. However, in manual assembly processes within such layouts, inefficiencies may arise from repetitive motions and handling of tools and parts, which can negatively affect productivity. In such cases, motion analysis is essential to identify wasteful elements systematically and propose improvements. MODAPTS provides a quantitative method for analyzing work motions and serves as a practical tool for designing standardized and ergonomic work procedures.<br/>Method: A single-operator body trim assembly cell in a domestic automobile plant was selected. The worker’s motions were recorded and analyzed using Heyde’s MODAPTS. Work was categorized into unit and element levels, and each element was classified as value-added or non-value added elements. Based on the frequency of MODAPTS codes, five units with the highest proportion of non-value added elements were identified, and their inefficiencies were analyzed to suggest ergonomic improvements.<br/>Results: A total of 468 elements were analyzed across 11 units, among which 323 elements (69%) were classified as non-value added elements. MODAPTS codes such as W5 (walking), G1 (simple grasp), and M4 (shoulder movement) were frequently observed in these non-value added elements. In particular, the top five units with the highest proportion of non-value added elements commonly exhibited repetitive tool setting, unnecessary walking, and re-grasping of tools and parts. Based on these findings, ergonomic improvement strategies were proposed, including the optimization of tool and part placement, revision of work sequences, utilization of wearable devices, and adoption of assistive tools.<br/>Conclusion: The MODAPTS-based analysis revealed a high proportion of non-value added elements in a cellular layout due to inefficient movement and work order. The proposed ergonomic solutions are expected to reduce musculoskeletal burden and improve work efficiency.<br/>Application: Based on the results of this study, it will be possible to propose ergonomic improvements for the cell-based layout process through MODAPTS analysis, contributing to the creation of a safer work environment.