MUSCLE ACTIVITY AND POSTURAL ANALYSIS OF A COMPUTER NUMERICAL CONTROL MACHINING TASK
Author: Muhammad Syafiq SYED MOHAMED, Isa HALIM, Akmal Hafiz AZANI, Mohanathas NADRAJAH, Siti Khadijah KHALIL
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