A Survey of Ergonomic Evaluation for Cart Tasks in an Electric Factory

摘要

The purpose of present study was ergonomics evaluation of cart tasks in electric factory. Present investigation consisted of two stages. In the first, a questionnaire was used to survey the operators with respect to musculoskeletal problems with cart tasks. In the second experimental phase of the study, sixteen material handling operators who had completed basic training have recruited from an electric factory. Each participant needs perform twelve bouts of material handing for 15 meters at one of two loads (i.e., 120 kg and 215 kg) and two cartwheel sizes (127 mm and 152 mm) with three cartwheel arrangement conditions (two swiveling cartwheels in handle side or front side and four swiveling cartwheels). In addition, Polar electrode belt placed around the chest was utilized to continuously measure heart rate. After each experimental condition, subjects need according their psychophysical response to rating of perceived exertion (Borg-RPE). Results of questionnaire survey showed that musculoskeletal injuries were associated with the handles position, the cart condition, handling materials, number of move times, and handling loads etc. The most musculoskeletal problems were reported with low back area (39.5%), shoulders area (38.4%), and feet and ankles area (28.8%). For cart design, operators reported that cartwheels (59%), cart platform (17.3%) and cart handle (15.6%) should be redesign in high priority. In field experiment, results of MANOVA revealed a significant main effect for cartwheel arrangement, and handling loads. There was also significant difference between handling loads. The mean handling time was longer in 215 kg (65 sec) than in 120 kg (52 sec). Mean heart rate and Borg RPE rating were higher in handling 215 kg. For cartwheel arrangement, four swiveling cartwheels condition was worse case. By contrast, the condition of two swiveling cartwheels in front side had better performance and lower workload. Further, there was a significant interaction between cartwheel arrangement and handling loads in handling time. Where participants were handling with 120 kg, there was no significant difference in handling time. By contrast, the mean handling time was significantly higher where loads were carried in 215 kg by four swiveling wheels cart. Suggestion of present study was conducted on lower handling loads and cart with two swiveling wheels in front side to reduce the workload.