High Density Polyethylene Pipes Quality Improvement

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Aseel Omar
Hiba Barhoosh.
Noor Ali
Samah Haskaykeh
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  Introduction: Six Sigma at many organizations simply means a measure of quality that strives for near perfection. Six Sigma is a disciplined, data-driven approach and methodology for eliminating defects (driving toward six standard deviations between the mean and the nearest specification limit) in any process from manufacturing to transactional and from product to service. Six Sigma is becoming a new world standard for customer satisfaction and profitability improvement. The Six Sigma methodology for solving problems is similar to many other approaches. The differences arise mostly from Six Sigmas emphasis on statistical techniques to isolate and quantify undesirable variations in process and product performance. The mathematical techniques and analysis are central to Six Sigma steps for problem solving. The purpose of this project is to study quality related problems in polyethylene pipe products and to improve their quality in Palestine Plastic Industries Company. This project aims at using a case study approach to show how six sigma methodologies can be used in order to improve the quality of polyethylene Pipe products. Sources of nonconformities will be studied. Six Sigma statistical tools will be used to identify and analyze defects. Design of Experiment (DOE) will be used in order to find the optimum settings of the production processes parameters and to reduce the defects. Based on data collected and after the DOE analysis the significant factor is haul off speed , interaction between screw speed & temperature and interaction between screw speeds & haul off speed. The results show that the optimum run was operating at high level off haul of speed and low level of screw speed and temperature, this run most of the samples that produced are match to the customer's specification.     Problem definition:   Our project purpose is to study the quality related problems in the extrusion PE pipes products and improve quality of the products by using Six Sigma methodology. The work in this project will be depending at the historical data from the manufacturing department, and our understanding of the extrusion process, by using the 6 methodologies and the approach of the design of experiment in order to reach company goals. Objectives:   This project aims to catch some objectives and results that reflex the progress in the production line and products also. 1-      To understand the extrusion process. 2-      To research and identify quality problems in P.P.I.Company. 3-      To identify commonly used Six Sigma tools and techniques. 4-      To solve the quality related problem and increased the quality of the PE pipes by using Six Sigma methodology (DMAIC) and DOE methodology. A Palestine Plastic Industries Company received a quality complaint in one of its product from the customer. The company was required to improve the quality of the product for its customers specifications. The purpose of this research is to study quality related problem in extrusion plastic pipes product and to improve the product using Six Sigma DMAIC methodology. The objectives of this study are to: 1.      Research and understand extrusion process. 2.      Research and identify quality problem in Palestine Plastic Industries Company. 3.      Identify commonly used Six Sigma tools and techniques. 4.      Solve the quality related problem and increased quality of the product using Six Sigma DMAIC approach.   In order to show that Six Sigma DMAIC methodology can be used to improve the quality of an extrusion plastic pipe product. The extrusion process and defect in extrusion products were studied. A customer complaint is one of high density poly ethylene pipe product was chosen as a case study. The majority of the rejection was due to thickness defect. The collected data was utilized to conduct root cause analysis of the problem and several statistical tools were used to study the data. The Six Sigma DMAIC (defines, measure, analysis, improve and control) approach was used to identify and reduce the thickness defect and to improve the quality of the plastic pipe. DOE was conducted in order to find the optimum setting of the extrusion process parameters and this result is improving quality of the product. Major findings: 1.      Six Sigma DMAIC approach can be used to improve a quality of extrusion plastic pipe product. 2.      Six Sigma tools such as Pareto chart, Cause-and-Effect diagram, Measurement System Analysis, Process Capability Study, Design of Experiment are very useful on improving the quality of product. 3.      Design of Experiment is a very useful tool to find the optimum setting of an extrusion machine parameter to reduce thickness defect on plastic pipe product. 4.      The combination of Six Sigma DMAIC approach and knowledge of extrusion process can be used to solve defect in process.   Limitations: The result of the study is limited to Palestine Plastic Industries Company. 1.      The study is limited to only one product manufactured in Palestine Plastic Industries Company. 2.      Only thickness defect on the plastic pipe part was studied. 3.      The analysis and results are based upon the researchers knowledge and experience.   Conclusions Six Sigma DMAIC approach can be used to improve the quality of the products in plastic industry. The result of this study proved that the quality of product in a plastic industry can be improved by using Six Sigma approach. Adapting Six Sigma as a part of business strategy definitely helps the organizations to achieve sustainable growth. Recommendations Related to the Case Study: The Palestine Plastic Industries Company is recommended to prepare a cycle sheet of the extrusion process parameters obtained from DOE. The cycle technicians are recommended to set the process parameter as per the cycle sheet so as to obtain the thickness of the part within customer specification. This will result in minimum thickness parts. Recommendations for Future Study: Six Sigma DAMIC approaches can also be used to solve other types of extrusion defects besides thickness. It is recommended to use the DAMIC approach and Six Sigma tools for quality improvement in not just extrusion companies but in other types of manufacturing and service industries as well. Six Sigma combined with lean manufacturing, continuous improvement, total quality management methods can be used in different industries to improve quality of products and services and reduce the cost with improved customer satisfaction.