Abstract:
Sulphonic acid loss is a major problem in non-soap detergent manufacturing process. It is estimated that the loss posts approximately
147.01 Baht/TB at the Unilever Thai Holdings Co., Ltd. This industrial research project aims at reducing the sulphonic acid loss at the
aforementioned company via the Six Sigma methodology. The study showed that the loss can be reduce by increasing the percentage
of active detergent (AD). During the first phase of the project, the cause and effect diagram, FMEA and 2-Sample t-test were utilized to
identify the root causes of the sulphonic acid loss. The root causes of the loss were the rework quantity, the water quality and the
neutralization time. These three root causes become the factors in the experimental design. The 2k factorial experimental designs with
center point, both within and outside the specification ranges, is utilization to find the optimal settings of the three factors. The experimental
results showed that the optimal settings for the three factors are 7 percent of rework, 0.986 ms of conductivity of water quality, and 180 sec
neutralization time. These new settings yielded 25.702 percent increase in the percentage of AD, and reduced the sulphonic acid loss to
1.260 Kg/TB, which was close to the reduction target of 1.060 Kg/TB initially set for this project. The project also provides a control plan
to aid the control implementation of these factors.