Ergonomics study and analysis of workstations in Tunisian mechanical manufacturing

Abstract

The workers’ performance in the mechanical manufacturing sector is the main factor for the improvement of productivity and quality. At present, it seems that the available information on the ergonomics and the working environment of the mechanical manufacturing actors is scarce. This study deals with the relationship between the working method and the workstation in injection mold manufacturing. An original methodology, based on the survey of operators using participatory ergonomic tools, is proposed in order to evaluate the ergonomic performance of 3 workstations: milling, turning, and drilling. The surveys concerned 3 operators. Obtained results showed that ergonomics play a key role in improving mechanical manufacturing. The results obtained from the analysis showed that ergonomics has a key role in the quality of the various tasks performed by operators. Using the Rapid Entire Body Assessment (RULA) and Rapid Entire Body Assessment (REBA) investigation tools, the examination of the workstations revealed 4 machining operations and 12 operator postures that have a direct influence on the performance of all machining stations. In addition, data from the analysis conducted on injection mold manufacturing revealed that neither the workstations were ergonomic nor the operators complied with the ergonomic rules. Based on the results obtained, a new standardized score is proposed for the RULA and REBA calculations. This score was applied and validated through another study conducted in a leaf spring manufacturing plant. The results of these studies were concretized by proposing the digital factory where CATIA software was used for the virtual design of the ergonomic workstations and their environments.

An Overview of REBA Method Applications in the World

“…One of them, the RULA method, is also used to analyse repetitive movements (associated with REBA) [6]. Due to these considerations, some studies present a broader and more complete analysis [46,66].…”

“…In the first case, this was achieved by means of simulations and, in the second, by means of photographs. Subsequently, several authors again combined methods (OWAS, RULA and REBA) [66,76] in iron and steel operations that involved milling, turning and drilling.…”

Ergonomics risk assessment among maintenance operators in a Tunisian railway company: A case study

“…The operators subjected to the ergonomic study were identified in Table 12, which lists the appropriate tasks. Each maintenance operation was divided into tasks containing each of the subtasks, as depicted by Boulila et al (2018). Table 13 presents the NSCs obtained for each maintenance task.…”

“…Some of them can be used for a general assessment; others can focus on the assessment of a specific risk factor in the context of a professional task. The tools list included mainly the following methods for: Analyzing awkward body postures such as Rapid Upper Limb Assessment (RULA; McAtamney & Corlett, ), Rapid Entire Body Assessment (REBA; Hignett & McAtamney, ) and Ovako Working Posture Assessment (Karhu, Kans, & Kuorinka, ). Evaluating manual material handling activities such as NIOSH Lifting Equation (Waters, Putz‐Anderson, Garg, & Fine, ). Evaluating comfort level assessment such as Body Parts Symptoms Survey (BPSS; Corlett & Bishop, ).Another motivation for evaluating discomfort movement is the development of digital human models for the ergonomic design of products, as described by Alkan, Vera, Ahmad, Ahmad, and Harrison (), Boulila, Ayadi, and Mrabet (), and Qutubuddin, Hussain, Kumar, and Reddy (). Thanks to recent progress, it has become easier for ergonomics experts to assess human factors in the planning phase before the design of the workstation (Prádanos, et al, ; Sutari, Nugroho, Yekti, Astuti, & Sari, ).…”

“…Another motivation for evaluating discomfort movement is the development of digital human models for the ergonomic design of products, as described by Alkan, Vera, Ahmad, Ahmad, and Harrison (2016), Boulila, Ayadi, and Mrabet (2018), and Qutubuddin, Hussain, Kumar, and Reddy (2019). Thanks to recent progress, it has become easier for ergonomics experts to assess human factors in the planning phase before the design of the workstation (Prádanos, et al, 2011;Sutari, Nugroho, Yekti, Astuti, & Sari, 2015).…”