Effects of Gate Locations on the Tensile Strength of Injection Molded Weld Lines

Abstract

As unfavorable molding defect, weld lines often result in reduced mechanical properties and poor appearance quality of injection molded parts. In this present work, effects of gate locations on the tensile strength of weld lines were investigated by changing the distances between two gates in 10mm, 20mm and 25mm, respectively. Test specimens were prepared with an all-electrical injection molding machine under different process parameters (injection speed, injection pressure and melt temperature). Visualization method and scanning electron microscope (SEM) were employed to further discuss mechanical test results. Study results indicated that tensile strength of injection molded weld lines was lessened as the increase of gate distances. Higher injection speed, higher injection pressure and lower melt temperature induced to lower weldline tensile strength whatever the gate locations were. Study results also illustrated that it was gate location rather than molding conditions had the most decisive influence on the weldline mechanical properties.