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RR974 - Identifying the human factors associated with the defeating of interlocks on Computer Numerical Control (CNC) machines

HSL were commissioned by HSE to carry out research which sought to identify reasons why operatives defeat interlocks on Computer Numerical Control (CNC) machines, and to obtain an understanding of the extent of this behaviour across the UK engineering industry. The findings from this research provided a number of valuable insights about the frequency of defeating interlocks and the influences upon this behaviour.

With regard to frequency of defeating, semi-CNC machines were identified as being commonly defeated in the sample* used in this research. Common activities associated with defeating were setting, proving, swarf removal and deburring. Managers, and operatives / supervisors felt defeating was commonplace (the ‘norm’).

With regard to influences, three sets of influences on operative behaviour (Predisposing, Enabling and Reinforcing) were identified as influencing behaviour in relation to defeating interlocks.

Interventions that take into account these influences could be developed to promote behaviour change. Suggestions for such interventions are provided within this report.

* It must be noted that these findings are taken from small-scale research and may not generalise to CNC machine users in the UK engineering industry.

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Updated 2013-06-06