document: Instability phenomena in the gas-metal arc welding self-regulation process Arc instability is a very important determinant of weld quality . The instability behaviour of the gas-metal arc welding -LRB- GMAW -RRB- process is characterized by strong oscillations in arc length and current . In the paper , a model of the GMAW process is developed using an exact arc voltage characteristic . This model is used to study stability of the self-regulation process and to develop a simulation program that helps to understand the transient or dynamic nature of the GMAW process and relationships among current , electrode extension and contact tube-work distance . The process is shown to exhibit instabilities at both long electrode extension and normal extension . Results obtained from simulation runs of the model were also experimentally confirmed by the present author , as reported in this study . In order to explain the concept of the instability phenomena , the metal transfer mode and the arc voltage-current characteristic were examined . Based on this examination , the conclusion of this study is that their combined effects lead to the oscillations in arc current and length
doc_bio_tags: B I O O O O O O O B I O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O B I I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O
extractive_keyphrases: instability phenomena arc instability weld quality gmaw process exact arc voltage characteristic metal transfer mode
abstractive_keyphrases: gas-metal arc welding self-regulation process