Acceptable peak forces and impulses during manual hose insertions in the automobile industry

Fifteen female subjects (21-59 years) were trained to execute simulated automobile hose insertion tasks using a psychophysical approach. Tasks were performed at 3 frequencies and in 5 postures. Subjects were instructed to apply their maximum acceptable force, during 750 ms, static insertion efforts, performed repetitively for 18 h of training and 9 h of testing. Maximum acceptable peak forces and impulses were calculated from the last 20 min of testing. Average within-subject coefficients of variation for acceptable peak forces and impulses were 9.0% and 8.1%, respectively. Mean acceptable peak forces for the pull back condition were 46% greater than those in the medial push far reach condition and decreased, on average, as exertion frequency increased. An average decrease of 17% was observed, across all postures, as frequency increased from 1 to 5 insertions/min. A significant main effect for posture was also found for acceptable impulse, following a similar trend as peak force. Subjects selected acceptable forces that were an average of 63% of their maximum voluntary effort, when averaged across all postures at a frequency of 1 per minute. Relevance to industry The current study provides maximal acceptable peak forces and impulses for females during rubber hose installations in automotive manufacturing. These data can be employed to establish tolerance limit values for females to reduce the incidence of injury associated with hose installation tasks, as well as ensuring quality. (C) 2007 Elsevier B.V. All rights reserved.