By placing the unit space at the center of a distribution, the Taguchi-Schmidt (TS) method in the Mahalanobis-Taguchi system enables positive and negative predictions of target variables. With the Schmidt orthogonal expansion used in the TS method, however, the estimated results depend on the order of items,and the rules for ordering the items have been unclear, which has made the TS method hard to apply. Accordingly, the ordering of items in the TS method was examined through the use of financial data on the basis of two ideas; correlation coefficients and the combined estimation of the S/N ratio. The results suggest that it is appropriate to use the order that maximizes the estimated S/N ratio and an order that increases the correlation between items and target variables.
Major results have been achieved by applying quality engineering methodologies in manufacturing industries. If quality engineering could also be applied in the home, where more than half of one's lifetime is spent, it should be able to improve the quality of one's life. A case study was made of the decision as to whether or not to stock spare supplies of consumable items for a printer used at home. The losses resulting from stocking and not stocking were defined and compared to obtain guidelines for the purchase and stocking of spare consumables. By considering different home environments, allocating their conditions to an orthogonal array, evaluating the losses associated with the array, and indicating the results of this analysis in a factorial-effect diagram, it was possible to present information that many users will find relevant.
In multikind small quantity production of human-machine-interface electronic components for automotive use, many complex assembly processes must be carried out by hand with the use of many tools and assembly jigs. A major challenge in tool and jig design is to establish an evaluation methodology for use in the conceptual design stage, but when human factors such as ease of operation are evaluated, conventional CAE simulation is unsuitable. Case studies were made of two promising methods: the virtual design method used for such purposes as product usability evaluation, and the method of making a simple test piece modeling a jig shape with corrugated cardboard etc. and carrying out parameter design. In one case, the shape of a pair of tweezers used in an assembly process was optimized by virtual design; in another case, a palette for applying lubricant was modeled with corrugated plastic and optimized. Both the virtual design method and the testpiece method were confirmed to be effective,though with remaining issues. In the future, it is considered possible to expand the use of these methods in total process design.
Vertical mills are used to crush fuel for coal fired power plants and to crush limestone to make cement. These vertical mills experience uneven wear during use, so especially at large plants, on-site maintenance often includes welded hardfacing. Because of the high hardness of the hardfacing material, however,the final hardfacing step, which is the finish grinding process, is extremely difficult. Beset with such problems as remarkably low grinding efficiency, abnormal grindstone abrasion, and noise, this process has become a bottleneck in the automation of maintenance and repair. The present study addressed the grinding problems in welded hardfacing and attempted to optimize the grinding method through functionality evaluation, When the results of the study were applied to actual production equipment, they demonstrated consistently efficient grinding and held grindstone abrasion to one third of its former value. The findings of the study became guidelines for the automation of the complete sequence of processes from hardfacing welding to finish grinding in the on-site maintenance and repair of large plant equipment.