There is a need to evolve toward robust production systems that can assure both high quality and high productivity with steadily improving consistency throughout the life cycle of the production line. In this study, quality engineering was applied for the first time to the conceptual design and operational verification of a production lihe. An evaluation method that evaluates the balance between quality and productivity throughout the life cycle of the production line comprehensively by simultaneous evaluation of loss, S/N ratio, and sensitivity in the conceptual design stage was developed, and its effectiveness was demonstrated on a model line. As this method was applied to the various production line ideas proposed by the designers, it was also developed into a standard simulation ulation system that can be put into practice quickly and accurately. Using the result, production line specifications were selected that achieved an 8% growth in production volume, a 3.1 db gain in S/N ratio (reproducible), and a 56% reduction in loss, compared with the initial conditions, Volume production began in 2007, and demonstrated once again that quality improvement can reduce cost, because improvement in the S/N ratio leads to loss reduction and loss reduction leads to greater productivity.
In design work, it is important to be cost-conscious. A skilled engineer can estimate production costs fairly accurately at the drawing stage. If a software-based estimation system could do the same, cost information could be obtained easily, facilitating cost-consciousness. In this study, an attempt was made to estimate component production costs from information in the drawings. The T-method(1) was employed. Although this method does not use information about correlations between items, we succeeded in improving the accuracy of the estimates by generating new items from such correlation information.
Clean water including trace amounts of minerals, such as tap water, mineral water, and natural spring water, is used for food, bathing, and beverages, and is circulated for cooling. A low level of microbial contamination is essential. When clean water is temporarily impounded prior to use, however, microbes tend to proliferate, and antimicrobial treatment becomes necessary, and it is extremely difficult to suppress microbial contamination over long periods of time without spoiling the cleanliness of the impounded water. We have developed an antimicrobial agent for water treatment that elutes an appropriate amount of silver ions into clean water. This antimicrobial agent was obtained by mixing a silver-based inorganic antimicrobial agent, which includes silver supported on a powdered inorganic ion-exchanger by ion exchange, into a resin. Compositions and molding conditions for making an antimicrobial resin which elutes a proper amount of silver ions continuously without being affected by noise factors such as water temperature and immersion time were optimized by the parameter design method of quality engineering. As a result, a new antimicrobial resin which elutes the proper amount of silver ions continuously was developed in a short period of time.
When quality engineering is introduced into a company, in many cases implementation does not go forward because of obstacles presented by conventional development and design systems and engineers' mindsets. This study concerns the results of quality engineering efforts made in the development and design department at the Kuwana Works of Hitachi Metals Ltd. The study was carried out through questionnaires concerning engineer's awareness of development capabilities and their level of understanding of quality engineering, focusing on changes that occurred over the period from quality engineering introduction to the present. The results were comprehensively analyzed using the MT system (RT method), correlation diagrams, etc., and management points concerning the introduction of quality engineering into the development and design department were considered. Although this summary is limited to the Kuwana Works,it was found important to get employees to understand the essentials of quality engineering and change their attitudes, and to plant the essential concepts of quality engineering in employees' minds through actual practice in quality engineering in about their first ten years of employment. It was also found necessary to work harder on encouraging team leaders.
Engine oil provides proper lubrication of the friction surface between the sliding piston and the cylinder and assures smooth transmission of the force applied to the piston by ignition, but there are issues involved with the quantity of oil used. Using too much oil is expensive because more oil is consumed than necessary,but if too little oil is used, friction between the piston and the cylinder liner increases, which can lead to such problems as reduced fuel efficiency,burning, sticking, and chipping of the ring lands. This study focuses on changes in fuel consumption related to suction force during the suction stroke. Parameter design was carried out on the piston, which greatly affects oil consumption,and its piston rings, which play a role in gas sealing and oil control,making use of simulation and the standard S/N ratio. As a guideline for the optimal design of the oil pan with respect to suction force, it was found that the oil pan should have a large volume and the oil duct should have a small area.