Abstract:
The manufacturing sector today faces high competition and there is an increasing demand for
customers to receive quality products, at the right time and at a competitive price. This then
calls for manufacturing firms to improve productivity more so in automotive manufacturing
industry. Master Fabricators Limited had in the past attempted to improve throughput time for
the buses manufactured by increasing the number of employees and hiring highly qualified
production personnel to steer bus body manufacturing. Those attempts yielded minimal
improvement effects and production stayed constantly at an average of 12 buses per month
over the years. The company was therefore reviewing their production processes to enhance
their efficiency and proper utilization of human labour. The aim of this study was to improve
productivity in bus body manufacturing, by reducing the production lead-time and lowering
the production costs. The purpose of the research was to identify bottlenecks and how to
eliminate or alleviate them and recommend proposals for improvement in productivity.
Cycle times including both the Value Added time and Non Value Added time were collected
for each production process. The current (as-it-was) Value Stream Map was developed through
plant walkthroughs, observation and in-depth interviews with the personnel on the production
floor and with the help of the Quality Companion 3 Software by Minitab. The analysis on
bottleneck processes was carried out and with calculations for takt time and using line
balancing technique, a proposed improved state Value Stream Map was developed again with
the help of Quality Companion 3 Software by Minitab. That was supported by the use of the
ARENA Simulation Software, with the input analyser generating the probability distributions
for each bus body manufacturing process.
The use of the Value Stream Mapping technique helped in unearthing the four bottleneck
processes; Fitting and Trimming, Materials preparation, Painting and Paneling
that hindered
faster delivery of the buses to the customers besides the high costs of production in terms of
labour. With that, a proposed improved state value stream for implementation by the company
was put forth. Simulation was then used to generate alternatives to the initial processes.
The results showed that using line-balancing technique by focusing on cycle time and
redistributing personnel in different production processes leads to productivity improvement
by increasing efficiency up to 13% and lowering labour production cost by 23%. From
Simulations, for the first alternative the results indicated an increase of seven (7) buses built
per month and cycle time reduced from 415.27 hours to 342.59 hours when processing the
framing section is changed from serial to parallel processing. With consideration of alleviating
the bottleneck processes in addition to parallel processing in the framing section, for the second
alternative the output increased to 31 buses (an increase of 19 buses from the initial processes) per month and the cycle time came down to 251.88 hours. In practice, this thesis demonstrates
the importance of bus body manufacturing to carry out their production processes by looking
entirety of the system rather than looking at isolated processes and trying to solve those isolated
problems. The research puts in practice the application of theoretical productivity improvement
tools of VSM and Simulation and more so, in low volume manufacturing where they have
potential to improve productivity