Factors affecting the shape of weld line

Experiments were carried out with a simple mold to examine the resin properties and physical characters of weld line, a surface defect that occurs when two flow fronts meet from different directions. There was no relation between the length and depth of the weld line. Furthermore, the length of the weld line was affected by elongational viscosity and surface tension, and the depth of the weld line was affected by specific heat and cooling rate of the surface of resin. As a result, a possibility of prediction of the shape of the weld line is presented.