Ergonomics evaluation for turning machinists in oil and gas industry

Abstract

It was discovered that there were ergonomics risk factors towards machinists during manual handling of large work pieces that may affect the health of the machinists based on the initial ergonomics risk assessment conducted on the CNC turning machine shop in oil and gas manufacturing company. The study aims to determine and improve the ergonomics risk factor that the machinists may be exposed to. In this study, the data were collected and analyzed using Cornell Musculoskeletal Questionnaire, Rapid Entire Body Assessment (REBA) and torque analysis. Survey result from Cornell Musculoskeletal Questionnaire found that most of the turning machinists experienced ache, pain and discomfort on their lower back, right hand shoulder and upper back. REBA analysis indicated that body posture applied during tightening headstock jaws is categorized as very high risk with REBA score of 11 and immediate improvement action is required. The root cause was identified using 5 Why methodology where torque wrench design limitation has been identified as the main contributor to the very high REBA score. The input torque applied by the machinist was reduced, and the location of the tightening torque applied for clamping and adjusting purposes was changed using manual torque multiplier equipment. The input torque applied by machinist reduced from 1200Nm to 44.4Nm, and the pulling force applied was reduced from 128.7kgf to 9.1kgf, significantly lowering the REBA score from 11 (very high risk) to 3 (low risk). The objective of the study has been achieved by significant improvement of REBA score for the very high-risk postures that the machinists are exposed to.