THE EFFECT OF RUNNER SHAPE ON MOLD FILLING AND PRODUCT VARIATION

摘要

In the plastics industry today it is generally accepted that full round runners provide the most efficient flow channel. However, when full round runners are implemented it is common for misalignment of the two halves of the runner to occur. This paper presents the effect that this misalignment has on mold filling and the resultant product. It is also common, in many instances and for many reasons, for other cross-sectional designs to be used. This paper also examines how subtle variations in runner design dramatically affects filling pressure, resulting in variations in molded parts. This study finds that there is a direct predictable relationship between the pressure drop through a runner and the ratio of the perimeter of the runner geometry to the cross sectional area of the runner.