An emulated mold with a circular cavity was built for the better understanding of the melt flow behavior of water-assisted injection molding process.Tracer technique was used for showing the melt flow.The cavity was filled alternately with red and green polypropylene tablets.After the mold was heated to make these tablets melt completely
water was injected into the melt to fill the cavity.The melt flow patterns were visualized under high-pressure water.The results show that the instabilities of water penetration into the melt from the water injector are caused by the high-viscosity melt around the injector
the melt near the mold wall flows back during the primary penetration
and the back flows become weaker and weaker along the penetration direction of water.The melt shrinkage during the secondary penetration is an approximately linear decrease process
and the melt shear flow is weaker than that during the primary penetration.At the same time
the fountain flow may occur in the melt front of water.