1-chapter I Introduction 6j3v28

CHAPTER I

INTRODUCTION

1.0

Background

In welding technology, the strength and appearance of the weld t are important properties when welding two metal pieces together. There are many factors that need to be considering getting better welding operation. Nowadays, welding parameters are the most common factor in welding process. The important parameter that usually used in welding processes such as current (Amp), voltage (Volt), travel of speed (mm/sec), wire speed and gas flow rate, but there are a lot of parameter in welding technology. In this study, welding process use Robotic Arc Welding unit to run the experiment by using GMAW (Gas Metal Arc Welding) welding type. Automate system use to run the welding process by programming the robotic welding, mix carbon dioxide 20% and Argon 80% gas is the main gas used in this experiment. This experiment will 1

be analyze by DOE (Design of Experiment) method robotic welding quality to fulfill the criteria of this study, by using this method to find better experiment methodology to run the experiment. This method also use to avoid ‘’ try and error’’ method to this experiment which could reduce the manufacturing cost and time consuming. Design of Experiment is very useful method for an engineer to manage their experiment wisely. Welding process by using automate system is very challenging area of research in the fields especially robotics technology. The task of automating the welding operation is to reproduce the experienced and skilled manual welder in of positioning the welding torch, and controlling the welding parameters. For an example in this case study the GMAW (Gas Metal Arc Welding) welding process. The stability of the welding process is very sensitive to the main welding parameters, especially current, voltage, welding speed, stick-out (length of wire out of the tube), shielding gas and arc length [1]. A small change in the distance between the welding torch and the component being welded may produce a considerable variation in the current and in the voltage. Current, voltage and shielding gas influence the transfer mode of melted filler metal to the component being welded, affecting the quality of the welds [2]. If the electric arc is unstable, defects such as lack of penetration profile, undercut or excessive spatter may occur. Process of this study is by using Robotic Arc Welding, the welding processes run by using this welding equipments. This welding operation using GMAW (Gas Metal Arc Welding) process to run the experiment on the butt and T-t welding plate. The results and data from the welding operation would be analyzed by using Minitab Software. In the Minitab Software, Design of Experiment method will be applied. The DOE is a method to gain knowledge and exploring new systematic process. The target of this study is finding the best parameters by using DOE for Robotic Arc Welding.

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1.1

Problem Statement During the welding process, have occurred discontinuities and distortion that

affect the weld bead appearance and their weld structure due to experiment results. This process involving of Robotic Welding operation by using GMAW type and the DOE method as medium to conduct the welding experiment. Furthermore, in welding process there are welding parameters required to consider during run the experiment. Select the right parameters that give best welding quality and by using the DOE method will help to provide a good welding procedure and also improve the quality of the weld bead. Hence, that makes the material experience extremely high and localized thermal expansion and contraction cycles, which introduce changes in the materials, which may affect its mechanical behavior along with plastic deformation.

1.2

Objective

The purpose of this project is to: 1) To investigate parameters robotic welding such as current, voltage, travel of speed and wire feed speed. 2) To reduce the defects of the welding process especially on the welding distortion and defects on the weld bead (internal and external). 3) To implement the new method of doing welding experiment by using Design of Experiment (DOE) by Taguchi method.

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1.3

Scope of Project The scope of the project is to optimize Robotic Welding parameters by using

DOE method. The study will include an experimental of welding process and through the non destructive test in order to analyze the weld bead properties of the butt and tt of welding specimen. Basic welding operations involves the preparation of the t metal (butt and T-t) by cutting process and send the plates for Coordinate Measuring Machine to get initial coordinate of the t plates. This is important step before the welding process run by using Robotic Welding.

By applying all the parameters, the

welding process run to find a good weld bead appearance especially on the welding distortion of the welding specimen. This welding experiment has to follow the Design of Experiment (DOE) method and the results from the experiments will be analyzed by using this method.

1.4

Significant of Project This project will provide a systematic welding experiment of the Robotic

Welding by using GMAW type. This study will provide a good deg tri- welding process. DOE was utilize to manage series number of experiment in order to achieve the best welding quality parameters and to generate regressions equation to predict the optimize parameters on distortion and defects. Hence, the best welding parameters may apply to welding industry especially on complex structure manufacturing. Furthermore, by completing this project, it could be the manual book for those who interest doing projects by using statistical method.

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