Abstract
During the assembly process, there are inevitable variations and noise factors in the material properties, process parameters and screening scheme, which may affect the quality of the product. Using the stress-strength model, an evaluated screening scheme method, by analyzing the variation of the defect density in the assembly process, is proposed and discussed. The influence of screening stress on product defects is considered to determine the screening scheme. We performed the defect stream analysis by calculating the recursive relations of residual defect density under multi-stress conditions. We find that the probability density function, which shows the defect changing process from latent to dominant relative to the time process, agrees very well with the historical data. We also calculate the risk as the entropy of the assembly task. Finally, we verify our method by analyzing the assembly process of a certain product.
Highlights
In the lifecycle of mechanical product manufacturing, the quality of the product depends on the quality of the assembly process [1]
Different screening methods aim at different product defects, so the first innovation of this paper is to establish the relationship between stress and defect by quantifying the stress of the assembly process, so as to optimize the selection parameters more precisely
Set an assembly task as a three-dimensional vector A (DI, P, Hp), where DI is the initial value of defect density, P is the set of processes included in the assembly task, Hp is the value of risk evaluation for this task (Figure 2)
Summary
In the lifecycle of mechanical product manufacturing, the quality of the product depends on the quality of the assembly process [1]. Only cases of the distribution of defects following a certain law are analyzed and they were not completely applied to the assembly process All these models implicitly assumed that the number of fatal defects is independent of the number of the latent defects in a device. Different screening methods aim at different product defects, so the first innovation of this paper is to establish the relationship between stress and defect by quantifying the stress of the assembly process, so as to optimize the selection parameters more precisely. Models consider both degradation and the relationship between stress and strength during the assembly process. An example related to a printed circuit board assembly (PCBA) is analyzed by our model
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