Abstract: The objective of this paper is to obtain the optimal setting of forging process parameters in order to reduce the rejection rate due to unfilling defect. Initially, the various forging defects that occur in the components during closed-die hot forging process are investigated. The investigation is done with the help of Quality Assurance department in a forging industry. During investigation, the various defects that causes high rejection rates are identified and unfilling defect which has major contribution in high rejection rate is selected for study purpose. The process parameters considered for study purpose are- billet weight, heating temperature, heating time each at three levels and required output is final job weight. To obtain the optimal process parameter combination, optimization is carried out by the Signal-to-Noise (S/N) ratio analysis of Taguchi method using L9 Orthogonal Array.