Assembly failures and action cost in relation to complexity level and assembly ergonomics in manual assembly (part 2)

Earlier studies have demonstrated strong relationships between manual assembly at high physical loadlevels and increased amounts of quality defects compared to assembly at low physical load levels. Arecent Swedish interview study of engineers in design and manufacturing engineering indicated thatassembly complexity factors are of additional importance for the assembly quality. The objective of thisstudy was therefore to examine the significance of high and low complexity criteria and the relationshipsbetween assembly ergonomics and assembly complexity and quality failures by analyzing manual assemblytasks in car manufacturing. In total, 47 000 cars were analyzed and the results showed severalsignificant correlations between assembly ergonomics and assembly complexity, assembly time, failuresand action costs. The action costs for high complexity tasks were 22.4 times increased per task per carcompared to low complexity tasks.Relevance to industry: Assembly ergonomics and assembly complexity factors interact. Both should beproactively considered in order to keep assembly-related failures and action costs as low as possible