Abstract
A study designed to estimate the hand speed of industrial workers in a setting simulating power press operation, and to assess the after reach hazards, was presented. The simulator was designed to imitate an industrial power press with reciprocating motion, and included dual palm button actuators at waist and shoulder level. After reach hazard was simulated using a plunger in the center of the die, which at random times displaced the workpiece from its proper position on the die. The time taken for the subject to replace the workpiece after releasing the palm buttons was measured. A total of 60 subjects were tested. All were industrial workers, and 51 had experience operating power presses. Experimental sessions lasted 30 minutes per worker, and four after reach times were collected for each subject for each palm button location. Hand speed was determined by dividing the distance from each palm button location to the die area by the appropriate after reach time value collected. Mean after reach hand speeds ranged from 0.66 to 2.18 meters per second (m/s). Most subjects were found to have greater hand speed from the shoulder level than from the waist level location, probably due to the assistance from gravity associated with the higher palm button location. Age and gender also appeared to be important considerations in predicting an individual's hand speed in an after reach situation. Young male workers had the fastest hand speeds. The authors conclude that in order to protect 95 percent of power press operators from the after reach hazard a hand speed constant of 3.0m/s would be required, which is significantly higher than the current OSHA standard of 1.6m/s.