Prediction of polymer pellet conveying behavior in microinjection molding machine

The higher requirements in dosage accuracy and material strength for products with micro features have made the solid conveying process in microinjection molding machines very important. Problems such as starve feeding and process instability will adversely affect quality more in microinjection molding than bigger parts. Studies have been carried out on the conveying of discrete solid polymer pellets in the plasticizing unit of microinjection molding machines using a newly developed discrete element modeling method to simulate polymer particle movements in the screw channel. The model takes into consideration the influences of adhesion and gravity. The effect of inclination of the conveying screw on the speed of solid conveying is investigated with both simulation and experimental approaches. The results of simulations agree with the results of experiments qualitatively.