Reduced Size Runner for an Injection Mold System

Abstract

A runner system for a multi-cavity injection molding system, the runner system having runners of reduced size.

What is claimed is: 
     
         1 . A runner system for a multi-cavity injection molding system, the runner system comprising a set of runners, each runner of the set in closest proximity to a mold cavity having a hydraulic diameter of 0.5-1.5 times a gate thickness for a part to be molded in at least one cavity of the multi-cavity molding system. 
     
     
         2 . The runner system of  claim 1 , wherein each runner of the set in closest proximity to a mold cavity has a hydraulic diameter of 0.5-0.9 times a gate thickness of a part to be molded in at least one cavity of the multi-cavity molding system. 
     
     
         3 . A runner system for a multi-cavity injection molding system, the runner system comprising a set of runners, each runner of the set in closest proximity to a mold cavity having a hydraulic diameter less than or equal to 20 times a peak melt pressure at which polymer is injected by the injection molding system, divided by (L/T) −1 , where L/T is a length-to-thickness ratio of a part to be molded in at least one cavity of the multi-cavity molding system. 
     
     
         4 . The runner system of  claim 3 , wherein the hydraulic diameter of each runner of the set in closest proximity to a mold cavity is at least sufficiently large so as to permit the flow of molten polymeric material therethrough and into the respective mold cavity. 
     
     
         5 . The runner system of  claim 4 , wherein the hydraulic diameter of each runner of the set in closest proximity to a mold cavity is at least 0.5 times a gate thickness of a part to be molded in at least one cavity of the multi-cavity molding system. 
     
     
         6 . The runner system of  claim 3 , wherein the hydraulic diameter is less than or equal to 8.25 times the peak melt pressure divided by (L/T) −0.889 . 
     
     
         7 . A runner system for a multi-cavity injection molding system, the runner system comprising a set of runners, each runner of the set in closest proximity to a mold cavity having a cross-sectional area less than or equal to a quotient of 700 divided by a peak melt pressure at which polymer is injected by the injection molding system. 
     
     
         8 . The runner system of  claim 7 , wherein each runner of the set in closest proximity to a mold cavity having a cross-sectional area less than or equal to a product of 199.63 times (peak melt pressure) −0.889 . 
     
     
         9 . A runner system for a multi-cavity injection molding system, the runner system comprising a set of runners, each runner of the set in closest proximity to a mold cavity having a cross-sectional area less than or equal to 315 times a peak melt pressure at which polymer is injected by the injection molding system, divided by (L/T) −2 , where L/T is a length-to-thickness ratio of a part to be molded in at least one cavity of the multi-cavity molding system. 
     
     
         10 . The runner system of  claim 9 , wherein each runner of the set in closest proximity to a mold cavity has a cross-sectional area less than or equal to 53.51 times the peak melt pressure divided by (L/T) −1.778 . 
     
     
         11 . A runner system for a multi-cavity injection molding system, the runner system comprising a set of runners, each runner of the set in closest proximity to a mold cavity having a cross-sectional area given by the formula: hydraulic cross-sectional runner area≦360,000/(peak melt pressure) 2 , where “peak melt pressure” is the peak melt pressure at which polymer is injected by the injection molding system. 
     
     
         12 . The runner system of  claim 11 , wherein each runner of the set in closest proximity to a mold cavity has a hydraulic cross-sectional runner area given by the formula: hydraulic cross-sectional runner area≦31,313*(peak melt pressure) −1.778 . 
     
     
         13 . A runner system for a multi-cavity injection molding system, the runner system comprising a set of runners, including
 a first branch set of runners, each of the runners of the first branch set of runners being in closest proximity to a respective one of the mold cavities;   a second branch set of runners, each of the runners of the second branch set of runners being in fluid communication with at least two of the runners of the first branch set of runners; and   a main runner in fluid communication with each runner of the second branch set of runners, wherein the main runner has a hydraulic diameter equal to at least the product of the hydraulic diameter of each of the runners of the first branch set of runners times the product of the number of branch sets of runners including the main runner raised to a power of ⅛.   
     
     
         14 . A runner system for a multi-cavity injection molding system, the runner system comprising a set of runners, including
 a first branch set of runners, each of the runners of the first branch set of runners being in closest proximity to a respective one of the mold cavities;   one or more additional branch sets of runners, each of the runners of the next-successive branch set of runners being in fluid communication with at least two of the runners of the next-lowest branch set of runners, each of said one or more additional branch sets of runners being identifiable as an integer value indicative of its level that is one higher than the branch set of runners in next-closer proximity to the mold cavities; and   a main runner having a branch value of one higher than the highest value of the one or more additional branch sets of runners, the main runner being in fluid communication with each runner of that highest value of the one or more additional branch sets of runners, wherein the main runner has a hydraulic diameter equal to at least the product of the minimum diameter of each of the runners of the first branch set of runners times the branch value of the main runner raised to a power of ⅛.   
     
     
         15 . A runner system for a multi-cavity injection molding system, the runner system comprising a set of runners, including
 a first branch set of runners, each of the runners of the first branch set of runners being in closest proximity to a respective one of the mold cavities;   one or more additional branch sets of runners, each of the runners of the next-successive branch set of runners being in fluid communication with at least two of the runners of the next-lowest branch set of runners, each of said one or more additional branch sets of runners being identifiable as an integer value indicative of its level that is one higher than the branch set of runners in next-closer proximity to the mold cavities; and   a main runner having a branch value of one higher than the highest value of the one or more additional branch sets of runners, the main runner being in fluid communication with each runner of that highest value of the one or more additional branch sets of runners, wherein the main runner has a hydraulic diameter equal to a hydraulic diameter of one of the runners of the first branch set of runners times a constant (K).   
     
     
         16 . A multi-cavity injection molding system having a plurality of hot runners therein, wherein a hydraulic diameter of at least one of the runners in closest proximity to one of the mold cavities is at least sufficiently large so as to permit the flow of molten polymeric material therethrough and into the respective mold cavity and is less than 6 mm.