Abstract:
This study aimed to reduce machine breakdown time of Giant Rock 1990 Stone Mill
Co.,Ltd case study due to high frequency of production process stop. This caused the earnings lost
from waiting time to performed Belt Conveyor maintenance and improvement which also caused
shorter life of Conveyor . The company income was reduced because totally breakdown
maintenance found during October 2008 to April 2009 (7 months) was 66.67 hours and have
Mean Time Between Failure at 20/14.71 hours. Normally, production capacity of this stone mill
is 1,000 ton per day, working time is 8 hours per day, means production volume 125 ton per hour.
Therefore the lost from this problem was 8,333.75 ton x 60 Baht per ton = 500,025 Baht. Thus,
the preventive maintenance system was utilized to reduce machine breakdown and time lost. The
result of preventive maintenance revealed that the time lost was reduced. From May-July, 2009,
the time lost was reduced by 1,324 minutes which was 22 hours and have Mean Time Between
Failure at 20/14.71 hours in 3 months. Cost saving could be calculated by 1 hour = 125 ton =
165,000 Baht. Therefore, the income was increased while the time lost was significantly reduced.