关键词: 流痕；聚丙烯；虎皮纹；评价体系；注塑制件

Abstract: Thin walled large-sized parts are prone to flow marks during injection molding, while traditional visual judgment is subjective and greatly affected by environmental and human factors. Therefore, a more objective evaluation system for appearance flow marks should be studied. The flow mark index (FMI) is introduced to quantitatively evaluate the severity of appearance defects in sample flow marks. Using a long rectangular mold to reproduce the flow marks caused by the injection molding of automotive interior and exterior trim with polypropylene.Measure the distance between the flow mark and the gate, evaluate the visibility of the flow mark, and observe the number of continuous stripes, and convert the above indicators into formulas to obtain FMI. The comparison between FMI and the actual injection molded sample shows good consistency in the degree of flow marks on the appearance. FMI not only provides quantitative indicators for the appearance defects of flow marks, but also provides reference for the causes of appearance defects that occur in the early formulation development, reducing the manpower and material investment caused by blind experiments.

Key words: flow mark; polypropylene; tiger stripe; evaluation system; injection molding parts