A Holistic Approach to Mitigating Warpage in Fiber-Reinforced Plastic Injection Molding for Automotive Applications 2024-01-2358

Fiber-reinforced plastics (FRPs), produced through injection molding, are increasingly preferred over steel in automotive applications due to their lightweight, moldability, and excellent physical properties. However, the expanding use of FRPs presents a critical challenge: deformation stability. The occurrence of warping significantly compromises the initial product quality due to challenges in part mounting and interference with surrounding parts. Consequently, mitigating warpage in FRP-based injection parts is paramount for achieving high-quality parts. In this study, we present a holistic approach to address warpage in injection-molded parts using FRP. We employed a systematic Design of Experiments (DOE) methodology to optimize materials, processes, and equipment, with a focus on reducing warpage, particularly for the exterior part. First, we optimized material using a mixture design in DOE, emphasizing reinforcements favorable for warpage mitigation. After careful consideration of physical properties, deformation stability, and economic feasibility, PP-Mica10+GF5 emerged as the optimal material. Next, we fine-tuned the injection processes for the selected material. We applied the response surface design in DOE, considering key process factors. This approach led to the identification of ideal conditions that minimize warpage. Finally, we addressed equipment optimization by designing a fixing jig, informed by injection molding simulations and real-world part deformations. In conclusion, we validated the optimized materials, processes, and equipment through real exterior part, resulting in an impressive 85% reduction in warpage, meeting stringent product design standards. This holistic approach serves as a versatile design methodology applicable to various FRP injection-molded parts, offering a promising pathway for warpage mitigation in the industry.