Muscle Activity and Postural Analysis of a Computer Numerical Control Machining Task

Muhammad Syafiq SYED MOHAMED, Isa HALIM, Akmal Hafiz AZANI, Mohanathas NADRAJAH, Siti Khadijah KHALIL

Faculty of Manufacturing Engineering, Universiti Teknikal Malaysia Melaka (UTeM), Hang Tuah Jaya, Duriang Tunggal, 76100 Melaka, Malaysia

Page 71 – 77   |   Vol. 8 No. 1 2023   |    Available online on 30 Jun 2023

Abstract

Computer Numerical Control CNC machining center is equipped with advanced features to achieve high accuracy, reliability, repeatability and productivity. However, CNC machining centers still expose machinists to ergonomics risk factors such as awkward postures, repetitive movements, heavy lifting and prolonged standing especially during manual material handling. The aim of this study is to redesign the existing CNC machining center to improve work posture and reduce muscle activity of the lower back. Muscle fatigue survey, Rapid Upper Limb Assessment (RULA) analysis and surface electromyography (SEMG) were used to assess subjective muscle fatigue, posture and muscle activity respectively. All machinists reported to experience muscle fatigue on the lower back area. Based on RULA analysis, the redesigned CNC machining center has improved the working posture of machinists as shown by a lowered RULA score from 7 to 3 for both right and left body side. SEMG results showed a significant decrease in muscle activity of the lower back. Therefore, this study concluded that the redesign of CNC machining center has shown has successfully reduced muscle fatigue and improved the work posture for the machinists.

Keywords

Muscle fatigue, RULA, SEMG, CNC

Acknowledgement

The researchers would like to thank the Faculty of Manufacturing Engineering, Universiti Teknikal Malaysia Melaka for funding this study by the University High Impact Short Term Grant (PJP/2017/FKP/H19/S01527).

© 2022 Human Factors and Ergonomics Society (HFEM). All rights reserved.

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Human Factors & Ergonomics Journal (HFEJ), eISSN: 2590-3705  is the official Journal of Human Factors and Ergonomics Society Malaysia.  The journal is published on a biannual basis. HFEJ aims to address current research in the field of Ergonomics in addition to the broad coverage of cognitive ergonomics, user experience, physical ergonomics and others such as transportation, industrial design and industrial engineering. HFEJ is a member of, and subscribes to the principles of the COPE (Committee on Publication Ethics), as such we only accept original work.