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Fig. 1. This facility installed an electric powered lift and tilt table (right) to improve worker posture.


taining an ergonomics program was presented to management.


On-Site Training for Employees Te following ergonomics risk fac-


tors have been observed in metalcast- ing facilities and were addressed in the ergonomics training sessions: • Forceful exertions • Frequent activities • Awkward postures • Long durations • Vibrations • Environmental stresses • Noise • Other (cognitive stresses, individ- ual differences, visual demands) Force. Force is the act of exert-


ing energy or the strength to move (push, pull, lift or carry) an object. In metalcasting facilities, force is used to lift material into furnaces, lift finished parts onto pallets, push carts filled with parts or scrap, push ladles of molten metal, and pull slag from the top of furnaces. Force can be measured using tools,


and the results should be compared to recommended limits. A grip dynamom- eter can be used to measure employ- ees’ strength so the right employee is matched with the right job. Exceeding the tolerance of muscle


will lead to fatigue, damage, failure and eventually injury. Workers must be able to sustain their energy expendi- ture (and power bursts) for eight to 12 hours/day. Transferring heavy parts can be strenuous, so tasks should be designed so that joints are in neutral postures, using low or no force or


speed. Remember to design tasks for lowering rather than lifting, and work- ers should try to use larger, stronger muscle groups, keep objects close to the body, stay healthy and exercise to increase their strength. Frequent Activities. Frequency refers to the number of times or how often a task repeats. Examples of frequent/ repetitive tasks risks at metalcasting facilities include hand grinding parts and inspecting parts on a conveyor. To address frequency issues, consider


different delivery methods of materials. If frequency cannot be reduced, mini- mize all other factors, such as awkward posture, as much as possible. Awkward Postures. Posture is the position of the body at any given time. Awkward posture occurs when the body deviates from the neutral position and increases the risk of injury. Examples of awkward postures observed at metalcasting facilities include bending forward to grab an object, holding the head/neck sideways or twisting to inspect a piece, reach- ing with arms out to level sand in sand casting, and holding the arms/ elbows at or above the shoulders to drill a part. In order to eliminate these awkward postures, each activity must be planned in advance. Long Durations. Duration, which deals with the length of exposure to an activity throughout the day, becomes a concern when another risk factor is present. So how long is too long? First, use a stopwatch to measure how long an activity is performed. Next, com- pare the cycle time to the known lim-


its provided by regulatory agencies. If duration cannot be reduced, exposure to other factors must be addressed. Vibrations. Vibration, the back-


and-forth or side-to-side motion of the body or a tool, is experienced in metalcasting facilities while using air-powered tools to compact sand in a mold, using saws or sanders to finish surface, and operating construction equipment/tractors or fork trucks. To address vibration issues, first


determine whether the vibration is low, medium or high frequency (Table 1). Next, assess which areas of the body are affected—the whole-body or various body segments. Vibration energy is absorbed by human tissues and organs and can cause muscle fatigue. Workers should report tools or equipment maintenance issues, reduce the duration of the exposure, use dampers on tools that vibrate and avoid continuous use. Avoid using vibrating tools in the cold, and keep hands warm and dry. Workers should allow the tool or machine to do the work and take 10 to 15 minute breaks every hour. Environmental Stressors. Environ-


mental stressors are the conditions of the physical environment that increase the demands on the body. Examples observed at metalcasting facilities include working near a furnace, pour- ing hot metal in a mold, and working outside when it is hot or cold. Humans are well adapted to toler-


ate heat, but they have limits. Up to 1 in 100 workers have heat related illness per year.


October 2011 MODERN CASTING | 25


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