Finite Element Simulation and Experimental Study of the In-Mold Graining Process

In-Mold Graining (IMG) is an innovative production technology applied to the skin wrapping of automotive interior components. In the design of automotive interior components of door panels and instrument clusters, to overcome process-related problems, such as the thinning of grain patterns and excessive reduction in thickness, simulation of the skin vacuum forming process is required. The Thermoplastic Olefin (TPO) skin material is investigated in this paper, and a viscoelastic mechanical model for this material is established. Dynamic Mechanical Analyzer (DMA) is utilized to perform scan for frequency and temperature, and the tested data is used to obtain key model parameters of the viscoelastic constitutive model. Based on the experimental data, the study explores how to calculate the relaxation time spectrum to describe the viscoelastic properties of TPO material during the vacuum adsorption process. Numerical simulation of the vacuum adsorption process of TPO material is conducted using Polyflow software, investigating issues such as the establishment of the solid model, meshing principles, and the selection of simulation models. Taking an inner door panel of vehicle as an example, simulations were performed and compared with the actual product's thickness for verification. The results indicate that the error between the simulated and the measured thickness is less than 5%, which can provide a reference for actual manufacturing.