Exergetic Control Charts (Variability Analysis in a Real Injection-moulding Industrial Application)

Decision concerning manufacturing process design and management, under sustainable constraints, are difficult to draw when taking into account variability of process conditions. Life-cycle analysis and exergetic analysis are even more jointly adopted to improve the accuracy of resource use efficiency – the so-called hybrid approach – even though these are based on the assumption of constant operating conditions.The paper discussed a new idea to take into account variability in hybrid exergetic LCA due to contingent conditions, by proposing an exergetic control-chart (ExCC) scheme to formalise the variable conditions. The idea behind the ExCC approach is that manufacturing sustainability analysis may change its outcomes when taking into account this ‘dynamic’ point of view.The control-charting scheme here proposed provides a mean to formalise explicitly the effects of variability in time, under the real operating conditions. The main advantage of the approach is to allow a more complete view of the process and to drive hints for improvements or innovations of processes. A real industrial case here presented of an Italian SME explains the potentialities of the idea as well as the limits of the current hybrid approaches available.