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Laminar Flow Ratio – A New Tool for Runner Cross Section Design
Laminar Flow Ratio is introduced as a new method for mold designers to use for runner cross sections whereby single mold plate runner cross sections can be designed to simulate the flow characteristics of matched mold plate runner cross sections and/or vice versa.
Design/Methodology/Approach
Specialized molds were designed and built with a series of runner cross sections, all having identical cross sectional areas and paths, but each mold having a different runner cross sectional shape. Tightly controlled injection process parameters using several different rubber compounds provided comparative analysis of molded runner samples.
Findings
Comparative analysis of molded runner samples combined with corresponding geometric analytical calculations reveal a ratio relationship between the cross sectional area of a runner and the perimeter of that same cross section runner -- herein introduced as the Laminar Flow Ratio. Research results indicate that comparative runner flow characteristics between different cross sectional shapes is more indicative of similar Laminar Flow Ratio than similar cross sectional area.
Research Implications
Injection and/or transfer mold designs incorporating runner cross sections can utilize the principles of Laminar Flow Ratio to determine the size of a particular shaped runner cross section to achieve similar flow characteristics to other cross sectional runner shapes. In addition to the obvious TSE rubber mold runner applications, this research suggests potential benefits and/or applications for gate sizes and shapes, and may even have relevant applications for runner designs in TPE and TPR systems.
Originality/Value
Laminar Flow Ratio is a new term and methodology introduced with this paper, having potential value for runner mold design, trouble shooting mold runners, and comparative runner analysis.
Keywords
Laminar Flow, mold, design, injection, transfer, runner, full-round, half-round, trapezoid.