Soldering is used to form electrlcal joints in many situations in manufacturing processes. To qualify work personnel for hand soldering, 100-percent sensory tests have been used. To eliminate sensory testing, a changeover was made to functional evaluation of the hand soldering process by measuremet of the current-voltage characteristic, and process conditions were quantitatively defined. Measurement errors were also reduced by using JIS Z 9090 to quantify measurement error, and a measurement technique for evaluation of hand soldering was established. At the same time, parameter design was performed and hand soldering process conditions stable with respect to noise factors were established.

In studying the functions of injection molding machines, we performed experiments using a bar flow die, which allowed the weight of molded articles to be varied easily according to the capacitieg of various dies used by injection molding machine users. A functional evaluation was carried out in which measured volume was the signal and the weight of the resin injected into the die was the output. At the same time, referring to studies of machine tools in which power consumption was treated as a basic function, we evaluated power consumption by the injection molding machine, using the weight of the molded article as a signal and electric power consumed in measurement and injection as outputs simultaneously. The gain was shown to be reproducible in verification tests,demonstrating that the two functions are functions of the injection molding machine.

With requirements for increased image quality in printers and combined printer-copiers there comes a need for increased structural rigidity. If carried out in hardware, experimental studies of structural rigidity take time and require costly prototypes. Optimization in this area is best performed during the engineering development phase before the shape of the product is finalized. The method applied here optimizes the shapes of the sheet metal parts of a structure through simulation, by replacing the structure itself with a simplified three-dimensional model. To ensure that the results would be useful in product designs, the method was directed toward a comprehensive optimization including cost, product size, and weight. As a result of this study, we were able to propose a method of obtaining results useful in product development quickly, during the engineering development stage.

A functional evaluation by quality engineering was undertaken in the development of a new power window. The evaluation was made by using standard signal-to-noise ratios, treating load, load position, and power-source voltage as noise factors, time as a signal factor, and vertical distance of window travel as an output characteristic. Life tests were carried out simultaneously and the results were compared with the functional evaluation results; the comparison showed that functional evaluation can also be used to estimate lifespan. A comparison of the improvement over a previous power window as measured by the life test and the improvement as measured by functional evaluation also confirmed that a quick functional evaluation provides an adequate indication. In order to develop a highly reliable product, it is necessary to evaluate the product during the initial stage of its development. The test results obtained in this study revealed that product life can be estimated in a short time by functional evaluation.

In the development of injection-molded products, the processes of designing and manufacturing molds are repeated through trial and error in order to be able to mold products into required shapes. In recent years, mold design by simulation using CAE has achieved good results in reducing development time and cost, e.g., by reducing the number of prototype molds. However, selection of optimal conditions relies heavily on experience, and no systematic practical methods have been established yet. Although several approaches using quality engineering have already been proposed and attempted, an established method has not been found. As a simulation vendor, in this study we attacked the problems of injection molding in order to provide design techniques that make use of simulation more effectively. In a previous study, we evaluated measurements of molded products by transferability, but some unsolved problems remained. This time we tested a new method in which shrinkage rate, which is a control factor that affects the shape of molded products, is evaluated directly, and were able to reach optimal molding by achieving even and stable shrinkage.

This is a study in the optimization of injection molding. Melted plastic resin has the property of shrinking as it cools and hardens. Since the shrinkage rate differs depending on location, some locations depart widely from their target dimensions. Research into the evaluation of transferability is directed toward the mitigation of this problem and to the establishment of injection molding technology. Experiments using a test piece for optimization of the molding conditions were reported previously. In the present study, the same evaluation of transferability was carried out through simulation, optimum solutions were found to the design of the product and mold, and improvement in the variability of shrinkage was confirmed. Repeatability was also confirmed between the simulation results and the actual molding process.