Robustness analysis of inspection design parameters for assembly of short-run manufacturing processes

Purpose – Defining a method for evaluating the robustness of models for defectiveness prediction and quality cost of inspection procedures in short-run assembly manufacturing processes.
Design/methodology/approach – First, the assembly process is decomposed into several workstations (working phases), each one potentially critical in generating defects. Then, exploiting some models of defect generation, the probabilities of occurrence of defects in each workstation are obtained. At this point, by the law of propagation of variances, the inspection design parameters’ uncertainty is derived. Finally, the uncertainty is propagated to two indicators related to the effectiveness and affordability of inspections. The proposed methodology is tested through the uncertainty evaluation of a case study concerning the assembly of hardness testing machines.
Findings – The proposed methodology allows the producers to identify the uncertainty of inspection design parameters for assembly of short-run manufacturing processes.
Research limitations/implications – The proposed methodology relies on the following
simplifying assumptions: (i) absence of correlation between the occurrence of defects and inspection errors in the same workstation and (ii) between different workstations.
Practical implications – The methodology may be extended and applied to a variety of different industrial contexts, related to short-run assembly manufacturing processes.
Originality/value – The quantitative approach, including the uncertainty evaluation, represents an important novelty with respect to the classical qualitative approaches in identifying the more suitable inspection procedure for short-run productions.

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Uncertainty evaluation, Inspection design, Short-run production, Defect generation