There have been many case studies on machining processes from the viewpoint of energy transformation in quality engineering reported with great success. In case of the spindle used in processing machines, quality characteristics such as temperature rise, vibration or audible noise have been traditionally measured. In this paper, a case study of evaluating the functionality of a spindle installed in a machining center is introduced from the energy transforming viewpoint. Using the traditional way of evaluation, the above said quality characteristics were individually measured at a high cost and several months were spent on development. The confirmatory experiment showed the quality improved, bearing temperature lowered and that the time spent on the study was one digit smaller.

Chemical plants require reliable monitoring systems for stable operation. Multivariate models have been used in many cases to make full use of equipped sensors. MTS (Mahalanobis-Taguchi　system) gives a good perspective for such applications. Because of the redundancy of sensors, strong co-linearity is inevitable in these processes. But the co-linearity contains ample information in conjunction with sensor failures. An extension of MTS modeling for co-linear data is proposed using singular value decomposition in this paper and some new ideas of modification of MTS for chemical plants are also suggested,

The objective of this paper is to predict a good oil-in-water emulsion, or "healthy emulsion", using the MTS method. Oil-in-water emulsion contains oil soluble compounds in the form of droplets that disperse in water. In an "unhealthy emulsion", oil droplets easily cause coalescence or re-crystallization and deteriorates the expected function of the compound. In the process of developing good emulsions, it has been difficult to predict its health, or quality. A Mahalanobis space was created based on the existing healthy emulsion recipes,and the Mahalanobis distance of a new recipe to be developed, was calculated to predict the quality. It was found from the study that MTS can distinguish a good recipe that does not easily cause coalescence or re-crystallization, from the one that causes such problems. By the item selection approach,. combinations of the items that affect the changes in Mahalanobis distance were found, thus the time of quality improvement was shortened.

Organic photoconductor (OPC) is equipped in the products such as plane paper copiers (PPC), faxes, or laser printers. It is consisted of charge transport layer (CTL), charge generation layer (CGL), under layer (UL) and substrate. Under layer is put between the substrate and exposure layer to improve charging ability and the adhesive power between exposure layer and substrate, to cover the substrate surface, also to prevent interference such as moire. OPC is initialized by repeatedly being used through the processes of charging - exposing - developing - cleaning - erasing. Regarding the life of OPC, wear occurs on CTL after running, charging ability weakens after repeated charges and exposures, and black spots in the background appear where the charge is not enough. The pin holes on UL create black spots in the background relative to film abrasion. In this report, two functions were studied : (1) charging function and (2) light decay function. For charging function, charge amount (Q) and charge potential (V) were considered as input and output respectively. For light decay function,time of irradiation and charge potential were considered as input and output respectively. Electrostatic fatigue (repeated charges and exposures) was used as a noise factor. Since the objective of this study was to find a formula to minimize micro-visional defects on UL, visional evaluation was also conducted. The number and size of pin holes were observed by copper electro-coating on the defects of UL. Since a smaller current is desirable, smaller-the-better characteristic was used for evaluation with time as a noise factor. As control factors,three factors from UL formulation, two factors from dispersion conditions, and one from UL, CGL, and CTL each were assigned to an L18 orthogonal array. From the results of this study, the behaviors of raw materials and the ingredients in the formulation were clarified in a short period of time and the number of defects was improved by 25.7 db compared with current formula. The life was extended twice by the improvement of moire and black spots in background.

Our company has been developing a semi-dry machining process, i.e., using minute amount of lubricating oil, to reduce machining cost also to improve the problems such as energy consumption, waste treatment or environmental deterioration. Currently, we are working to optimize the drilling condition for aluminum material using Taguchi methods. In our first paper the machining conditions without drill breakage were reported. This paper explains an experiment focused on the input/output energy relationship. The results showed that new semi-dry machining condition gave an outstanding improvement on quality, efficiency and energy consumption compared with current machining conditions.

Many component parts of mechanical devices such as bearings, valve sheets,screws, sheets couplings, and gears function together with their counterparts. On the surface of such component parts, bearing force produces rolling and slipping. It is inevitable to generate adhesive wear. In an extreme case, galling occurs on the osculating plane. It is the skin sore caused by friction or abrasion. To avoid such a phenomenon, materials such as aluminum alloy, graphite and titanium garbide are used. Various types of surface coating are also applied. In this paper, the sliding characteristic of stainless steel with a high corrosion resisting property was reviewed under a high load condition. The earlier study of this subject was conducted in the late 80's, where the objective quality characteristics such as load and friction were focused, although larger-the-better SN ratio was used in the study. In this report however, dynamic SN ratio was used to study the function by converting the outputs into the relationship between load and friction. From the results, a more appropriate and detail evaluation of the sliding characteristic under galling condition became possible.

Color balance, one of the important characteristics of photographic color prints is evaluated using the hexagonal coordinate indication of characteristic values and the sensory evaluation of photographs so far. But rich experiences of experts were necessary to judge by these methods. Therefore it was required for us to create objective and quantitative evaluation method. This time, using the MTS method that calculate Mahalanobis distance of color balance, the standard space is desirable gray, and evaluate by Smaller the better type SN ratio, it enabled to evaluate dispersion of color balances of the photographic color prints simply and objectively even for the persons who are not experts.