Effect of Quality on the Economics of Assembly Processes

Abstract

Assembly processes include mechanized and manual techniques, both of which are affected by the quality of the component parts being assembled. It is virtually impossible to guarantee 100% quality of components during manufacture, so it must be expected that defects will proceed to the assembly process. During manual assembly the operator can act as the inspector and discard any obvious faulty parts, thereby minimizing defective assemblies being produced. During a mechanized assembly, defective parts are less easily removed, so more defective parts are found in the final assembly. This chapter investigates the effect that defective parts have on assembly processes and analyses the cost of providing components at various quality levels to the cost of producing a subsequent assembly. The problems of defective components on both manual and mechanized assembly operations are also discussed, as well as establishing that defect parts must be kept to a lower level than is generally considered realistic. This implies that greater attention must be paid to component manufacture and inspection if effects during assembly are to be minimized. Small subassemblies are preferable to large assemblies, providing functional checks are made during construction.