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Proceedings of the 9 Symposium on Applied Science, Business & Industrial Research – 2017
ISSN 2279-1558, ISBN 978-955-7442-09-9

Downtime Analysis of Expeller Machines – A Case Study

Wijayarathna MDTN, Appuhamy PADAN
Department of Mathematical Sciences, Wayamba University of Sri Lanka
hsdpatharu@gmail.com
ABSTRACT

In each and every industrial sector, all machines and machine system components
are critical and their maintenance is of prime importance. The main objectives of the study
were to investigate machine downtime and to identify the machines with low productivity.
In the present case study, the primary data has been collected during three months period
from an oil manufacturing plant, situated in Dankotuwa. The data includes monthly
operating time (in hours), down time (in minutes) of each machine and number of working
machines per day. The best fitted distribution for downtime of each machine was identified
using Anderson Darling Statistic. Two-State Markov Chain model was used to calculate
steady state probability of breakdown. Moreover, mean down time of the Expeller
machines was used to identify the machine with low productivity. The study revealed that,
machine breakdown time heavily impacts on reducing production of virgin coconut oil in
that plant. 3-parameter Weibull distribution seems to be the best distribution to explain
variations in breakdown time of almost all machines. During study period, around 50% of
the machines in that plant were out of order and there was a loss of approximately 60 liter
of oil per day to the company.

KEYWORDS: Breakdown, Mean down time, Weibull distribution

unexpected breakdowns and new
1 INTRODUCTION
maintenance operations integrated into
Maintenance plays a key role in various production process. According to the study
sectors. In recent times, with the concept of reported by Mobely (2002) about 15% to
effective and efficient maintenance, 40% (average 28%) of the total daily
industrial sector has taken new steps in order production was lost due to maintenance
to make machines in good operating activity.
condition to achieve the expected results. Due to unexpected failure interrupt
Maintenance Engineering is the procedure production process and losses company’s
taken up to keep the machines in working expected output and thereby reduce
condition. Machine maintenance is expected profit. Therefore, comprehensive
important in any industry because it directly machine breakdown analysis is a must for
impacts on the production. Planned any production company in order to identify
maintenance reduces the regular the necessity of the installation of a proper
breakdowns and increases the efficiency of maintenance system to achieve expected
the production process. targets. The main objectives of the study
were to investigate the prevailing situation
The goal of maintenance is to ensure that of the expeller machines’ breakdown time of
the performance of the machines is one of the pioneer oil manufacturing
satisfactory. A good maintenance system company in Sri Lanka, to fit a best
contributes to provide efficient customer distribution for machine downtime, and to
service, high quality, safety, on time calculate the probability of the machine
delivery, and also to reduce cost of breakdown. Finally, study identifies the
unnecessary maintenance. In recent past machines with low productivity due to
preventive maintenance in industries was breakdown.
taken into the research. The results of these
studies have been utilized to reduce

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