Analysis of human work decisions in an aluminium smelter

Automation is often considered a dominant influence in the process of making most products. However a number of investigators have concluded that decisions of staff are actually a key influence on quality and safety of production plants. In this study, decisions of staff during repetitive, manual or semi-automated operations in a production plant have been observed over years to understand the decisions and their impact on efficiency and quality. A range of operations were observed in an aluminium smelter including replacement of anodes. Many key decisions lay embedded behind the operating procedures themselves and these 'implicit' decisions and relationships to design of the operating system are examined with respect to the removal of carbon dust from the cell electrolyte. A hypothesis about graduated scales of sensory information compared to sensory information presented in a binary way is developed. The importance of feedback during and after the task is also noted.