Reduction of Injection Moulded Plastic Part Warpage Using Advanced Gas Assisted Injection Moulding

Abstract:

Dimensional and shape accuracy are the basic quality criteria of almost every injection moulded plastic part, manufactured in the engineering industry. They are dependent on many production conditions as part and moulding tool design, material structure properties and injection parameters. Generally, it is very difficult to achieve high geometrical accuracy during injection moulding, therefore, dimensional tolerances for plastic parts are usually many times larger than in the case of metals. However, according to requirements of the engineering industry, demands for the plastic parts dimensional accuracy keep growing permanently, what also extends to the growing shape complexity of the produced parts. Due to this tendency, engineers must look for more and more advanced solutions to meet market requirements and keep the competitiveness of their product. In consonance with all this, this paper presents a case study where the progressive gas assisted injection moulding is used as a solution for the plastic part warpage reduction while any other conventional methods failed. The study is performed making use of part from the automotive industry, initially produced with unacceptable deformations. In the first step, the real manufacturing state was studied to determine the warp behaviour. Subsequently, the process parameters and cooling conditions were unsuccessfully modified while trying to reduce deformations. Nevertheless, these were effectively eliminated by the only application of internal gas support to the melt injection phase. A numerical modelling based on Finite Volume and Finite Element Method was also used in the case study in order to mathematically represent the fluid, thermal and mechanical processes during the process of injection moulding.

• Periodical: Materials Science Forum (Volume 862)
• Pages: 200-209
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.862.200
• Online since: August 2016
• Authors: Miroslav Košík*, Jozef Bílik, Daynier Rolando Delgado Sobrino
• Keywords: Gas Assisted Injection Moulding, Numerical Modelling, Plastic Part, Warpage Reduction

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