In the manufacture of soap, as an alternative to the purchase of fatty acid feedstock,methods of making the fatty acids in-house from a lipid feedstock were studied. Specifically, parameter design was carried out for a reaction that uses enzymes to decompose beef tallow into fatty acids. A preliminary evaluation was performed by use of the omega transform with the yield rate as the characteristic value(experiment 1). Working from the results, a new evaluation based on the S/N ratio of the reaction rate was carried out with the reaction time as the signal factor and the degree of purity of the feedstock as a noise factor (experiment 2). A confirmation experiment appeared to show an improvement in the S/N ratio with nearly the same gain, although there were major effects due to the noise factor. When cost and loss were compared, it was found that a reduction in loss could be anticipated if the selected production conditions were used instead of the comparative conditions.

In an effort to improve the production equipment that forms the plastic surface layers of photosensitive drums used in electrophotography, parameter design was carried out to obtain a new temperature control system for controlling the coating fluid temperature. The goals were to shorten the time needed to switch tempreatures so that the system could respond quickly to changes in the type of fluid, changes in the coating temperature, and so on. The previous method of controlling the temperature of the coating fluid by circulating it several times through a warm water jacket covering the coating fluid pipes was replaced with a simple one-pass heat exchange, and the temperature change was evaluated:the temperature difference between the coating fluid and the jacket water was the input; the change in the temperature of the coating fluid was the output. Performance adequate for varied production conditions was sought by including such noise factors as the temperature, viscosity, and flow rate of the coating fluid. Eight factors related to heat transfer were selected as control factors and assigned to an L18 orthogonal array. The results of the experiment showed which parameters were effective for temperature control and enabled heat exchange performance under the optimal conditions to be improved. The effectiveness of parameter design was demonstrated by confirming that the time needed to switch temperatures was shortened in actual coating equipment.