Productivity Improvement In Bus Body Manufacturing

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