Abstract:
The purpose of this study is to reduce the variation of four characteristics of Jumbo roll tissue, which are the machine direction tensile strength (MDT), the cross machine direction tensile strength (CDT), the stretch (MDS) and the bulk. The Six-Sigma approach was applied to define the problem, analyze for the causes and determine the improvement methods. It was found that the variation could be reduced by improving the machine capability and revise the work instruction. In addition, this research used the Central Composite Design method to generate the experimental runs to study the effects of two factors, which were the refiner load and the dry strength chemical addition rate. Then, the Stepwise regression was utilized to determine the relationship equation between the significant terms and the responses. The Desirability function was then used to find the optimal setting. The improvement results showed that the Target index (TI) of the MDT was reduced from 0.08 to 0.04, the TI of MDS was improved from 0.40 to 0.02. The TI of Bulk was decreased from 0.59 to 0.23 while the TI of CDT increased from 0.13 to 0.15. Based on the controlled target (TI < 0.15), the TI of the Bulk was still over the target. Regarding the Capability index (CI), after improvement, all characteristics had the CI in the controlled target (CI < 0.85). The CI of MDT was reduced from 1.27 to 0.56. The CI of CDT was reduced from 1.17 to 0.32. The CI of MDS was improved from 0.92 to 0.73 and The CI of the Bulk was improved from 0.90 to 0.68.