Assembly in Action: Small-Scale Manufacturer Makes Large-Scale Improvements
As a small-scale manufacturer, Ligon Brothers Manufacturing Co. (Almont, MI) was facing increased competition and unacceptable injury rates. In 1997, there were 47 recordable injuries. This signaled a need for a change. In particular, the K-137 transfer press workcell, with operators, had been reporting less than optimal production and 10 recordable injuries.
The K-137 manufactured stamped metal support assemblies with five distinct operations. The operations included press operation, nut welding, leg welding, unloading and box building. These operations required each person to repetitively extend, bend and twist his or her back while reaching, loading and unloading the stamped parts.
The company sought to analyze the K-137 workcell and redesign the work process. The company contacted Humantech (Ann Arbor, MI). Humantech conducted risk assessments and interviewed the operators to identify areas where ergonomic risk could either be eliminated or greatly reduced.
The recommendations were then ranked and categorized according to impact and ease of implementation. This enabled Humantech to highlight those that were high-impact and low-cost. In total, 12 recommendations were identified. The majority of them fell into the high-impact, low-cost category.
One of the highest impact improvements was installing conveyors between the presses and welding stations. This eliminated double handling of parts and alleviated the bends and twists required to remove the parts from storage bins. Other high-impact, low-cost improvements included installing light-beam activated switches at the leg welding station. This reduced awkward wrist postures and operator fatigue. Repositioning the nut welder staging table closer to the press conveyor decreased the operator’s reach.
The most challenging and logistically difficult recommendation was to eliminate the box builder position by switching to recyclable, collapsible plastic dunnage. Although this recommendation requires coordination with Ligon’s clients, the result would eliminate the ergonomic risk associated with that operation and reduce the number of man-hours needed in the workcell.
Ligon Brothers implemented seven of Humantech’s workcell redesign recommendations by the end of 1998. The K-137 workcell has increased its production from 200 parts per hour to 250 parts per hour while maintaining operator levels. Recordable injuries decreased from 10 in 1997 to three in 1999. At the end of 2002, the workcell was operating with no recordable injuries—a reduction of 100 percent.
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The workcell ergonomic improvements have spurred the company to invest in ergonomics training for its operators, a train-the-trainer program and further investigations into redesigning all of its operations into efficient workcells. These programs have reduced plantwide recordable injuries from 47 in 1997 to only 13 in 2002.
For more information on ergonomic analyses, call 734-663-6707 or visit www.humantech.com.
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