Application of Six Sigma Method with DMAI Approach in Railway Manufacturing Company

As one of railway manufacturing company in Southeast Asia, quality is an important factor in maintaining customer satisfaction and one of the key success in business competition. During the railway production, there is problem in the assembly process of car body sub assembly, namely underframe. Defective products have been found which cause the underframe to be repair, so the underframe production is delayed. The type of defect is porosity, which results from the welding process during the assembly process. Therefore, this study uses the Six Sigma method with the Define – Measure – Analyze – Improve (DMAI) approach to give improvements on welding process so the defect which is porosity will be reduced or may not exist and to maintain the quality. Define phase using Supplier – Input – Process – Output – Customer (SIPOC) diagram and Critical to Quality (CTQ). Measure phase using c-Chart to know the process stability, then Cp and Sigma Level to know the process capability. Fishbone diagram and Failure Mode Effect Analysis (FMEA) are used in the analyze phase. The result of FMEA is the base to design improvements in the improve phase, the improvements are material storage characteristics, workstation design and procedure display. Introduction As one of railway manufacturing company in Southeast Asia, quality is an important factor in maintaining customer satisfaction and one of the key success in business competition [1]. Also, this railway manufacturing company has to improve its quality, which is the products that have been produced must be zero defects [2]. The core product of this railway manufacturing company is train. One train consist of two main components, which are bogie and car body. The components that arrange one car body are shown in the Figure 1. One of car body sub assembly, namely underframe (Figure 2), has its problem. The problem is, defective products have been found which cause the underframe to be repair, so the underframe production is delayed. The production data of underframe is shown in Table 1. It can be seen from Table 1 that the type of defect is porosity. The identified defects are located in different connections, which are on the side sill connection and the center sill connection. There are 12 joints that need to be inspected on each connection, so the total is 24 joints. Porosity (Figure 3) comes from the welding process during the assembly of underframe’ components. The components of underframe (Figure 2) are front end, rear end, side sill, center sill, and cross beam. Therefore, this study uses the Six Sigma method with DMAI approach to give improvements on welding process so the defect which is porosity will be reduced or may not exist and to maintain the quality. 1st International Conference on Engineering and Management in Industrial System (ICOEMIS 2019) Copyright © 2019, the Authors. Published by Atlantis Press. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/). Advances in Intelligent Systems Research, volume 171