Analysis of Incomplete Filling Defect for Injection-Molded Air Cleaner Cover Using Moldflow Simulation

Abstract

A large-sized cover part for air cleaner was injection molded with ABS resin, and its incomplete filling defect was analyzed using commercial Moldflow software. To investigate the effect of processing temperature on incomplete filling defect, tensile properties, weight loss, and phase separation behavior of ABS resin were evaluated. The tensile properties of dumbbell samples were not changed up to 250 ∘ C and decreased significantly thereafter. SEM micrographs indicated no significant changes in the status of polybutadiene rubber phase below 250 ∘ C. These different test results indicated that ABS resin little affected the thermal decomposition in processing temperature range. The Moldflow simulation was performed using measured thickness of molded cover and actual mold design with the defects. As expected, the cover part showed unbalanced filling and incomplete sections. To improve these defects, two possible cases of hot runner system have been simulated. When applying modified 5-gate system, the maximum injection pressure was decreased approximately 5.5% more than that of actual gate system. In case of 6-gate system, the maximum injection pressure reduced by 23%, and the injection pressure required to fill is well within the range of the molding equipment. The maximum clamping force of 6-gate system was also significantly reduced than that of actual and 5-gate system.

Calibration of a numerical model for heat transfer and fluid flow in an extruder

“…The measurement at 160 • C did not reach the zero shear viscosity at the converging left side of the measurements and therefore has not been used for further analysis. These measurements were then These values are similar and comparable to the measurements of Shin et al [14]. All measurements tend to reach higher viscosities than the model.…”

“…The viscosity model used in the simulations was validated by performing rheometer experiments in a rotational rheometer. Viscosity was measured and compared to calculated values defined by the Cross-WLF model of Shin et al [14].…”

“…Usually, the glass transition temperature is chosen. According to Shin et al [14], this value is 100 • C, RepRap Wiki [16] stated a similar value of 105 • C.…”

“…A widely used model for polymer viscosity is described in Koszkul et al, Shin et al, Jena et al [13,14,15]. The socalled Cross-WLF model is based on the relation for the zero-shear viscosity: Tr is a chosen reference temperature.…”

“…Literature research brought only a few measurements on temperature dependence of ABS viscosity. In order to validate the measurements of Shin et al [14], it has been decided to individually perform experiments at Vienna University of Technology. The analysis took place using Rheometer 301 by the company Anton Paar [22] (plateplate configuration) at values 160, 180 and 230 • C with a slid diameter of 2mm.…”