Assembly - February 2009 - (Page 44) ASSEMBLY Workstations Ergo Numbers Guidelines help identify risk factors and improve productivity. ork heights, reach standards and other ergonomic issues should be addressed by engineers when designing assembly workstations, especially in lean environments where job rotation is common. W When workstations are designed with operators in mind, they can perform assembly tasks more efficiently. Photo courtesy Lista International Corp. By Austin Weber Senior Editor Unfortunately, no two operators are alike when it comes to height, weight, posture, arm length, arm strength and other variables. A workstation setup that “feels right” to one person may become a source of aggravation to another individual, leading to wasted motion. Manual assembly processes can be improved if engineers consider ergonomic guidelines that address job-related stressors such as force, position, repetition and vibration. Numerous guidelines provide direction on implementing ergonomic processes, as well as the design of jobs, tasks, equipment and tools. “Poor ergonomic design directly impacts productivity, efficiency and quality from an assembly line,” warns Wayne Maynard, director of ergonomics at the Liberty Mutual Research Institute for Safety (Hopkinton, MA). “Guidelines are essential references that offer useful tools and practices for successful ergonomic program management, including risk factor identification, analysis and evaluation techniques, and suggested ergonomic interventions.” Interventions can include specific workstation design recommendations, such as suggested heights for fixed and adjustable workstations. Some guidelines even provide anthropometric tables that apply to employees in a specific industry or occupation. “Ergonomic guidelines are generally design [criteria] for products and processes that are intended to keep work at a level where 90 percent to 95 percent of the industrial population can perform the tasks with a low risk of incurring a musculoskeletal injury,” notes Julia Greenwald, senior ergonomist at the Ergonomics Center of North Carolina (Raleigh, NC), which is housed in the Edward P. Fitts Department of Industrial and Systems Engineering at North Carolina State University. By designing workstations with operators in mind, people can perform assembly tasks without being injured. “They can usually perform tasks more 44 ASSEMBLY / February 2009 www.assemblymag.com http://www.assemblymag.com
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