Prediction of weld interface depth and width at optimum laser welding temperature for polypropylene

In this preliminary research, Through Transmission Laser Welding (TTLW) of polypropylene is systematically studied through finite element method (FEM) and response surface methodology (RSM) combined approach. The thermal field simulated by solving a three-dimensional transient heat diffusion equation using COMSOL Multiphysics. Statistical software Minitab v17 has been used to develop an experimental design as per central composite design. The objective of the work is in twofold. The first objective of the study aims to develop mathematical models to predict the weld interface depth (MD), weld interface width (MW) and maximum temperature (Tmax), primarily in terms of the process line-energy. The developed mathematical models are examined by analysis-of-variance (ANOVA) technique to check their adequacy. The second objective of the study is to establish an optimised combination of laser welding parameters (laser power, scanning speed and spot diameter) to prevent polypropylene thermal degradation. The desirable MD and MW conditions have been predicted for the established optimised set of laser welding parameters. The results from this preliminary investigation using a FEM approach, can provide the basis for future design of experiments to help predict and obtain enhanced weld quality for polypropylene specifically and other polymer material system in general.