مدل سازی تجزیه و تحلیل هزینه منفعت بازرسی در خط تولید

Production management aims to maximize profit by increasing salable output while reducing the cost related with inspection, where inspection is defined as the measurement and quality assessment of items produced. This study is based on a semiconductor production line with consecutive deteriorating machines. Each machine is inspected via the items it produces and an inspection result triggers a machine's repair, if needed. Inspection related cost includes fixed and variable cost of inspection capacity, Yield Loss Cost generated due to unsalable throughput, and delivery delay cost caused by inspection flow-time. The effects of inspection capacity and inspection rate on cost are investigated using analytical and simulation models. Under a given inspection capacity, Yield Loss Cost decreases with growing inspection rate until a minimum is reached, and then starts to increase with further growing rate. This increase is explained by the impact of higher load on the inspection facility, which prolongs the inspection response time. Thus, an optimal inspection rate can be derived for a given inspection capacity. It will be shown that the higher the capacity, the higher the optimal rate, and the lower the yield loss. Determination of optimal inspection capacity considers the capacity cost against the other costs and minimizes the total expected inspection related costs.

Production management strives to maximize profit by increasing the revenue, gained by the production throughput, while simultaneously reducing the overall cost of production. Some of the production cost is generated by applying quality improvement activities through the production line, which are intended to drive higher throughput and in turn increase the revenue. Since revenue is a function of the average sale price, which rather depends on the market and not on production management, it is disregarded in this study. Rather, only the cost of goods sold is considered which corresponds to the overall cost of production. Therefore, it is assumed that minimizing the overall cost will consequently and equivalently maximize the profit. This work originates in semiconductor wafer fabrication, where dies are produced on silicon wafers that stream through the production line, via process and inspection steps. It studies the cost related to quality improvement applied by inspection of the items produced. Distinction is made between end-of-line (EOL) inspection performed on the final product, and in-line (IL) inspection performed on partially processed items throughout the production line. This study investigates the scenario of applying IL inspection.

This work studied the cost benefit of inspection in production. It considered a typical production line embedded with in-line inspection. It investigated the impact of inspection capacity and inspection policies on various performance measures, such as yield, flow time and utilization. Based on this, it developed an economic model for quantifying the value of higher quality while considering the cost of the inspection facility and its operations. This paper's novelty is in presenting a comprehensive economic model that enables to maximize the benefit of inspection. The results and conclusions drawn of this work strengthen known expectations with an analytical model, and presents new findings. In-line inspection capacity and inspection policies significantly impact Inspection Related Cost. Clearly, inspection capacity cost decreases with inspection capacity. Under fixed capacity, variable Inspection Cost and FT delay penalty decrease with the IR. Furthermore, under fixed inspection capacity and while growing the IR, Inspection Related Cost decreases to a minimum and then increases thus forming a quasi-convex curve. The curve's shape is explained by prolonged inspection response due to higher load of the inspection facility. Finally, the overall Inspection Related Cost decreases with inspection capacity to a minimum and then increases. The minimum Related Inspection Cost is determined by selecting the inspection capacity acquired and the IR exercised. The minimum Inspection Related Cost is obtained at moderate inspection facility utilization. The utilization slightly increases with inspection capacity reduction, but it still remains moderate and stresses that minimized cost is not necessarily obtained where the utilization is maximized. Future research directions suggest a few opportunities. Study the impact of inspection facility's availability on cost. Evaluate dynamic inspection policies versus the applied FMR policy. Improve Inspection Related Cost by modeling accumulated learning over time, due to data collected via inspection. Study the impact of other arrival and service processes, such as statistical distribution functions.