This report describes the three-year efforts of quality engineering promotion personnel to spread quality engineering within a firm in order to change its corporate culture and gain acceptance for a new technological paradigm. The MT system was used to numerize the promotion activities quantitatively, comprehensively, and objectively. Evaluation topics (32 items) suitable for capturing changes in corporate culture were configured by the card method, and 63 people involved in the activities were ranked on ten levels by three raters. Changes in the firm over time were evaluated from these data by the both-sides T method in the MT system. This made possible a quantification of the corporate culture,suggesting that this technique may be an effective tool.

Press fitting is a fastening method that provides a robust joint at a low cost, so it is widely used in industrial products. In the press-fitting processes, quality control is commonly practiced by measuring the press-fit force and height, but quality problems still occur, such as press-fit force out of tolerance and cracks in press-fit parts(molded parts). One reason for these problems is that appropriate press-fitting conditions have not been determined in the design stage. In this study, we performed a parameter design focused on the relationship between lateral pressure applied to a shaft and displacement of the shaft, and attempted to optimize the press-fitting conditions for molded parts. a

In many factories, compressed air is used to blow off water, oil, or cutting chips. If this could be done efficiently with greater blowing power, in many cases production processes would flow more smoothly and production costs could be reduced. As an aspect of air blow system selection, air blow nozzles were studied and a functionality evaluation of the air blow nozzles commonly used in factories was carried out. As a result, it became possible to discriminate between good and bad nozzles and select an optimal nozzle with reduced pressure drop and improved air-blowing power.

Computational fluid dynamics and Taguchi methods were applied to study a fin tube heat exchanger used as all evaporator in a CO2 heat pump water heater. The object was to find an optimal structure that would provide greater heat exchange with lighter weight and a lower fan speed, and would suppress variations in performance due to manufacturing tolerances. An automated calculation system was constructed by using Microsoft EXCEL and a VBA macro,making it possible to carry out an L18×L18 direct product experiment. The results provided a detailed understanding of how design parameters affected the evaporator's performance, variability, and performance per weight (roughly equivalent to performance per cost). From this information, an evaporator structure was developed that outperformed the current structure and was about 30% lighter.

Injection molded products have multiple quality requirements concerning dimensional accuracy, surface accuracy, burrs, etc., and these are affected by many factors, such as flow conditions, injection parameters, injection molding machine structure, and die structure. Previous quality engineering studies of injection molding systems have attempted to optimize each of these factors separately,but separate optimization has not always optimized the system as a whole. In this study, all factors involved in the total injection molding system were considered simultaneously and evaluated by simulation. This led to the simultaneous achievement of high dimensional and surface accuracy and greatly suppressed burrs, a result that had not been achieved by the conventional separate optimization method.

A major need of powder metallurgy industries is innovative production methods that can increase production speed to maintain a comparative advantage in cost competition. This optimization study undertook the task of greatly increasing production speed while suppressing variation in weight by examining the relation between design factors in the pressure forming process and variation in weight experimentally. When a powder filling machine is operating ideally, the weight of the filling powder is proportional to filling time so that metal powder falls at a constant rate from the shoe box and the weight of the powder in the cavity does not vary. To evaluate powder filling, we optimized powder filling using a proportional relation between the dwell time of the shoe box and the filling weight, and obtained a moderate degree of reproducibility in the S/N ratio. Application of the results of this study to mass production is expected to improve productivity 2.6-fold.