Polymer Inserts for Flash Control in Liquid Silicone Rubber Insert Molding
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Solution Overview
Problem
The existing insert molding processes for liquid silicone rubber often result in excessive flash, which increases manufacturing steps and costs due to the need for flash removal from the final product.
Innovation Solution
A mold system with polymer inserts and partitions that form a compression fit around the component, reducing or eliminating flash by creating a positive shut-off during the molding process, utilizing a base with a cavity and pockets separated by thin partitions and inserts made from fluoroelastomers or perfluoroelastomers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional insert molding processes are used for liquid silicone rubber, then the molding process is simple, but excessive flash is generated that requires removal
Solution Approach 1:
The mold structure is segmented into multiple functional components: polymer inserts positioned around the component, thin partitions separating pockets from the cavity, and a port system for liquid delivery. This segmentation allows each element to perform its specific function in controlling flash while maintaining overall system manageability
Solution Approach 2:
Polymer inserts act as intermediary elements between the liquid silicone rubber and the component surface. These inserts create a compression fit that forms a positive shut-off barrier, preventing flash formation without requiring direct contact between the liquid rubber and component, thus enabling precise flash control
2Manufacturing precision
If flash removal steps are added to eliminate excessive flash, then manufacturing precision is improved, but the number of manufacturing steps and cost increase
Solution Approach 1:
The polymer inserts are pre-positioned in the mold around the component before liquid silicone rubber injection. This preliminary action creates a pre-load compression fit that establishes a positive shut-off barrier in advance, preventing flash formation during the molding process itself rather than requiring subsequent removal steps
Solution Approach 2:
The compression fit mechanism, which initially might seem to add complexity, actually converts the potential harm of flash formation into a benefit by creating a positive shut-off that eliminates flash entirely. The tight seal formed by the polymer inserts transforms what would be a problematic excess material issue into a controlled molding process
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution eliminates the need for subsequent flash removal, providing a pre-load and tight seal that prevents excess flash formation, compatible with both hot runner and cold runner mold operations, and reduces manufacturing costs.
Implementation Method 1
the inserts have a dimension that is smaller than that of the base and partitions so as to form a compression fit around the component during the molding process
Implementation Method 2
The inserts are formed from a polymer, such as a fluoroelastomer or a perfluoroelastomer
Data Source
AI summary
An object is formed on a component with a positive flash shut-off during insert molding operations. The mold has a base with a cavity and a port that delivers a liquid to the cavity. The base has a component support structure for supporting the component and pockets formed on opposite sides of the cavity. The pockets are slightly spaced apart from the cavity by thin partitions. Inserts located in the pockets and are formed from a polymer. Both the partitions and inserts comprise the component support structure. The inserts have a dimension that is smaller than that of the base and partitions so as to form a compression fit around the component to reduce or eliminate flash down the component during the molding process.