Problems with machine safeguards in automated installations

Abstract

Even though the automation of production has come a long way, injuries from machine movements remain a problem. The focus of the current study is on problems of machine safeguarding in automated installations. How come automation accidents have occurred despite the presence of safeguards? The paper reports problems related to safety devices from 76 accidents in automated production, and relates them to findings from other studies and the problems described in handbooks and other literature. Safeguards are categorized according to their function, and the study addresses the nature of the safeguarding problem rather than the frequency with which problems arise. There are, above all, four problems of safeguards that have commonly emerged from accident investigations: no or a low level of safeguarding, safeguards not being used, safeguards not stopping all machine movements in the risk zone, and safeguards not being capable of providing protection under the circumstances that prevail. It is shown that all types of safeguards have their problems; and, in particular that they do not always function adequately in conjunction with the handling of production disturbances. A production installation should not automatically be regarded as safe simply because it possesses an impressive range of safeguards. Relevance to industry The practical relevance of the paper lies in it addressing safeguarding problems that go beyond those described in regulations and standards. It highlights accidents that occur despite the presence of safeguards, and shows how safeguards may be deficient in an operational setting.