A review of machine-guarding recommendations

A series of machine-guarding drawings were developed during the 1940s, which represent the relationship between gap size and safe distance. Since the development of these drawings, larger and more comprehensive anthropometric surveys have been conducted, but they have never been compared with the drawings. The purpose of this investigation was to determine whether these original recommendations presented in the drawings are still consistent with data in the larger anthropometric surveys, especially relating to women and minorities, who are now much more prevalent in the American workplace. In this study, data from six anthropometric surveys were compared with the original machine-guarding recommendations. To minimize the percentage of the population at risk, the length dimensions were chosen from the 99th percentile male population, and thickness dimensions were chosen from the 1st percentile female population. Many of these recommendations were found to be valid, although several important modifications were suggested. Several currently recommended dimensions show no correlation to the incompressible joints utilized in this study, and it is recommended that they be eliminated. The recommendations are presented in tables of maximum gap size and minimum distance.