Shrinkage and Warpage Minimization of Glass-Fiber-Reinforced Polyamide 6 Parts by Microcellular Foam Injection Molding.

Youngjae Ryu,Joo Seong Sohn,Chang-Seok Yun,Sung Woon Cha

doi:10.3390/polym12040889

Abstract

Shrinkage and warpage of injection-molded parts can be minimized by applying microcellular foaming technology to the injection molding process. However, unlike the conventional injection molding process, the optimal conditions of the microcellular foam injection molding process are elusive because of core differences such as gas injection. Therefore, this study aims to derive process conditions to minimize the shrinkage and warpage of microcellular foam injection-molded parts made of glass fiber reinforced polyamide 6 (PA6/GF). Process factors and levels were first determined, with experiments planned accordingly. We simulated designed experiments using injection molding analysis software, and the results were analyzed using the Taguchi method, analysis of variance (ANOVA), and response surface methodology (RSM), with the ANOVA analysis being ultimately demonstrating the influence of the factors. We derived and verified the optimal combination of process factors and levels for minimizing both shrinkage and warpage using the Taguchi method and RSM. In addition, the mechanical properties and cell morphology of PA6/GF, which change with microcellular foam injection molding, were confirmed.

Highlights

The automotive industry is attempting to reduce automobile weight by replacing metal parts with plastic ones to improve gas mileage [1]
polyamide 6 (PA6) reinforced with 18 wt% of glass fiber and 22 wt% of minerals was used as the test material
The 27 simulations showed an average shrinkage in the flow direction (FD) of 0.589%, average shrinkage in the transverse direction (TD) of 0.888%, and warpage of 0.7501 mm

Summary

Introduction

The automotive industry is attempting to reduce automobile weight by replacing metal parts with plastic ones to improve gas mileage [1]. Injection molding is a suitable process for manufacturing automobile plastic parts with complex shapes [2]. This process consists of plastic resin pellets placed in an injection molding machine’s hopper, followed by entering a heated barrel containing the rotating screw to be melted. There have been many studies on manufacturing plastic automobile parts using injection molding mainly using polypropylene (PP) and polyamide 6 (PA6)-based materials [4,5,6,7,8,9,10].

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Methods

Conclusion