Effect of Process Parameters on Short Fiber Orientation along the Melt Flow Direction in Water-Assisted Injection Molded Part

Haiying Zhou,Hesheng Liu,Qingsong Jiang,Weiping Li,Tangqing Kuang,Zhixin Chen

doi:10.1155/2019/7201215

Abstract

The short fiber orientation (SFO) distribution in the water-assisted injection molding (WAIM) is more complicated than that in traditional injection molding due to the new process parameters. In this work, an improved fiber orientation tensor method was used to simulate the SFO in WAIM. The result was compared with the scanning electron micrograph, which was consistent with the experiments. The effect of six process parameters, including filling time, melt temperature, mold temperature, delay time, water pressure, and water temperature, on the SFO along the melt flow direction were studied through orthogonal experimental design, range analysis, and variance analysis. An artificial neural network was used to establish the nonlinear agent model between the process parameters and A11 representing the fiber orientation in melt flow direction. Results show that water pressure, melt temperature, and water temperature have significant effects on SFO. The three-dimensional (3D) response surfaces and contour plots show that the values of A11 decrease with the increase in water pressure and melt temperature and increase as the water temperature rises.

Highlights

With the development of advanced, economical, and environmentally friendly society, higher requirements are placed on the performance of plastic products
To verify the simulation results, water-assisted injection molded tubes with shortfiber-reinforced composite were observed by scanning electron microscopy (Nova NanoSEM 450) with an accelerating voltage of 5 kV
The experimental observations are consistent with the simulation results, indicating that the iARD-RPR model can well predict the short fiber orientation (SFO) distribution in overflow water-assisted injection molding (WAIM)

Summary

Introduction

With the development of advanced, economical, and environmentally friendly society, higher requirements are placed on the performance of plastic products. SFRPCs have gradually replaced metal materials in some fields, making them widely used in aviation, automotive, shipping, and medicine [2, 3]. High heat capacity, and good thermal conductivity of water, the advantages of WAIM over GAIM are high product efficiency, more uniform and thinner residual wall thickness (RWT) [6]. In short-shot WAIM, the mold cavity is partially filled with melt, followed by the injection of water into the core of melt. In overflow WAIM, the mold cavity is completely filled with melt, followed by the injection of water that pushes the melt into the overflow cavity to form a part with a hollow cross section. Compared with the standard injection molding, WAIM offers significant advantages in the preparation of shaped hollow plastic parts with uniform RWT. Present researches on WAIM focus on the distribution of RWT [9], the length of water column penetration [10, 11], and the defects of molded parts [12, 13]

Methods

Results

Conclusion