Optimization of wall thickness and geometric accuracy in stretch forming combined with incremental sheet forming using grey relational analysis (GRA)

Abstract

Abstract In this paper, experimental investigation of hybrid forming process which combines stretching and single point incremental sheet forming (SPIF) process is done. The process combination has many advantages such as higher formability, short forming time, uniform material distribution etc. as compared to SPIF process alone. The process comprises of partial forming of part shape using stretching in first step, followed by forming of complete part shape using SPIF process in second step. Effect of three parameters namely stretching amount, pitch and tool diameter is investigated on response characteristics namely wall thickness and geometric accuracy of formed parts. Taguchi’s L25 orthogonal arrays (OA) is used to design the experimental plan. It is observed from the experimental results that, stretching amount and pitch has considerable influence on wall thickness. Also, pitch and tool size significantly affect part accuracy. Grey relational analysis (GRA) is used for multi-performance optimization of most affecting parameters to optimize the wall thickness and geometric accuracy. Validation of optimization process is done by carrying out experiments using optimized values of process parameters. It is observed that the optimum set of process parameters results in optimum wall thickness and geometric accuracy of formed parts.