On-line quality engineering has been used to optimize process control for products,which are already being mass-produced, but has not been applied to new products from the initial development stage. For greater front loading, however,it becomes necessary to optimize manufacturing process control from the development stage. A switch (one of our main products) as used as a model for developing an optimization method that began applying on-line quality engineering from the development stage. The developed method, based on a virtual model,succeeded in achieving an optimal mass-production control system from the initial ramp-up stage of mass production. In on-line quality engineering, optimization is usually based on past results. Optimization based on a virtual model is an innovative approach, not reported elsewhere, which makes optimization possible when a new process is being designed.

In air conditioning systems, comfort and energy conservation are important quality indicators for customers and society. To improve these quality items, we focused on the air guide vanes placed at the air outlet of an air conditioning system and studied techniques for controllillg the airflow. The ideal function of the guide vanes was defined in terms of the airflow vector (velocity and flow angle), and the cross-sectional shape of the guide vanes was used as a control factor. The velocity distribution near the guide vanes was calculated by computational fluid dynamics (CFD) and a nominal-is-best parameter design was carried out in two steps. As a result, a technique for designing guide vane shapes with high reproducibility and tunability was developed.

Evaluation and optimization by generic functions were used in an attempt to improve the processing capability and productivity of laser machining on coated surfaces. The preset output value of the laser machine tool was used as an input and removed weight was used as an output. The pattern width, representing the pattern shape, was used as a noise factor, processing patterns were allocated for control factors, and parameter design was performed for two types of machine tools with different laser pumping sources. For a diode-pumped laser, although the gain was only 2.6 db, some reproducibility was obtained. For alamp-pumped laser, however, reproducibility could not be obtained. To improve the gain, an S/N evaluation was carried out for each signal. In addition,to analyze the reasons why reproducibility could not be obtained, the JIS Z9090 procedure was carried out to clarify the separated S/N ratio and measurement errors.

As competition among firms becomes increasingly intense, there is growing interest in simulation as a means of speeding up product development, but before designers can put simulation to practical use, there is an urgent need to improve the automation environment. In this study, quality engineering was combined with an in-house analytic model of a photosensitive drum drive unit, a direct product experiment was performed with both control factors and noise factors assigned to an orthogonal L₁₀₈ array, and a nominal-is-best evaluation was carried out. In selecting the optimal conditions, both the variability and the mean value of the maximum amplitude on the photosensitive drum, which is a smaller-is-better characteristic, were reduced by reducing the sensitivity, and the reduction was almost perfectly reproduced in a confirmatioll experiment. When components were actually manufactured under the optimal conditions and tested in a working copy machine, the measured mean value was nearly identical to the mean value predicted by the simulation.

UV curable adhesives are widely used because of their excellent optical properties and productivity advantages. When such adhesives are used for optical components, in addition to their adhesion performance, their impact resistance and assembly accuracy become key issues. Regarding assembly accuracy, the alignment of optical components is particularly important. Misalignment problems can be gellerally classified as either initial misalignment, due to curing shrinkage, or misalignment due to degradation caused by temperature changes and other factors encountered in the field. Initial misalignment can be avoided or corrected by fine adjustment during the assembly process, but misalignment occurring in the field poses serious problems, because it occurs while the product is being used by the customer. This report describes an attempt to evaluate the function of maintaining alignment by focusing on dimensional changes of the adhesive due to temperature changes and the reversibility of such dimensional,changes, using the standard S/N ratio. Parameter design was performed using the composition of the adhesive as a control factor, an optimal adhesive composition was found, and a major improvement in the maintenance of alignment was achieved.

CAE has come into wide use as an efficient design tool, and CAE tools incorporating quality engineering have been developed to obtain robust designs. When quality engineering is applied in actual CAE work, however, the necessary calculations take an extraordinary amount of time if ordinary CAE models are used. This problem was attacked in a parameter design study carried out for a deep drawing process by CAE. The study showed that good reproducibility could be obtained by use of the sheet thic㎞ess reduction ratio in the deep drawing process as a characteristic value, which provided a guideline for simplifying the CAE model in the parameter design. As a result, it was possible to show how to make CAE more efficient in a concrete case, the problem that had hampered the use of CAE in parameter design was solved, and a contribution was made to the application of quality engineering to design work.