Maintenance efficiency improvement for chilled water system by reliability centered maintenance: A case study of chilled water system for plastic injection molding

Abstract

The main objective of this study was to improve the chilled water production system for a factory. It was a case study of a plastic injection industry due to the fact that problems on the failure of chilled water production system could result in the shutdown of the entire factory’s production process. This research adopted the concept emphasizing on Reliability Centered Maintenance. It was used to determine 59 necessary maintenance tasks for maintaining each part and component influencing the important functions of the system. In regard to the conventional practices, there had been 16 tasks used for these maintenance functions. In fact, they had been designed out of the general expectations obtained from the engineers’ common experiences. Although the new type of maintenance tasks appeared to be more numbers than the old ones, they only needed 38.28% less time for proactive maintenance tasks than the old ones. Regarding the new tasks, it enhanced water pressure control system in order to be regulated more constantly through use of ‘redesign’ task. As a consequence, it increased the overall efficiency of the chilled water production system up to 141.87%. This was shown through some important measurement indexes of the efficiency e.g. ‘mean time between failure’ (MTBF) of the system. Besides, it reduced the numbers of chilled water production failures owing to the broken pipe by 100%. At the same time, the 59 mentioned tasks also helped reduce the numbers of the quality problems caused by the chilled water production system failures 43.71% less than the convention practices; while, the numbers of the problems for the chilled water temperature not meeting the set level decreased 70.37% less than before. They lowered cost expense for chilled water production system energy from 30,240 Baht 21,168 Baht per month, as well.