Sealed Electrical Plug Metal Insert Overmolding
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Solution Overview
Problem
The poor material connection between plastic and metal in electrical connectors due to different thermal expansion coefficients leads to leakage issues, requiring complex measures for sealing, such as pre-encapsulation or additional sealing elements.
Innovation Solution
Using a curable gel or adhesive, like perfluoropolyether or silicone gel, to seal the interface between the plastic and metal inserts during the overmolding process, ensuring a reliable and tight connection even under high vibration loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If metal inserts are overmolded with plastic to produce electrical connectors, then the connector structure is integrated and manufacturing is simplified, but the connection tightness deteriorates due to different thermal expansion coefficients of plastic and metal
Solution Approach 1:
A sealing compound is introduced as an intermediary substance between the plastic connector housing and metal inserts. This sealing compound compensates for the thermal expansion differences between plastic and metal, maintaining connection tightness while allowing the overmolding process to proceed. The sealing compound fills gaps and prevents leakage paths that would otherwise form due to differential thermal expansion.
Solution Approach 2:
The connector assembly becomes a composite structure consisting of plastic housing, metal inserts, and sealing compound. This multi-material composite approach leverages the advantages of each material: the structural integrity of plastic, the electrical and mechanical properties of metal, and the sealing capabilities of the sealing compound, thereby resolving the tightness issue while maintaining manufacturing simplicity.
2Reliability
If complex measures such as pre-encapsulation or additional sealing elements are used to achieve tightness, then connection reliability is improved, but device complexity increases
Solution Approach 1:
The sealing function is merged into the overmolding process itself by incorporating the sealing compound application as an integrated step. Rather than adding separate sealing elements as distinct components, the sealing compound is applied and cured as part of the manufacturing process, combining the sealing function with the structural formation in a unified approach.
Solution Approach 2:
The sealing compound is applied in a manner that allows it to self-distribute and self-seal the interface between plastic and metal. The compound flows into gaps and interfaces during application, then cures to form a continuous seal without requiring additional mechanical sealing elements or complex assembly steps, enabling the system to seal itself.
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
The solution provides a simple, cost-effective, and reliable sealing method that maintains connection integrity between plastic and metal, preventing leaks and ensuring the connector's functionality in harsh environments, such as within vehicle engine oil areas.
Implementation Method 1
the sealant or adhesive mass is used to achieve the tightness at the plastic/metal interface
Implementation Method 2
The sealant or adhesive mass is preferably a curable gel, in particular a perfluoropolyether gel
Implementation Method 3
the sealant or adhesive mass is preferably a curable gel
Data Source
Figure 1
Figure 2~3
AI summary
In an electrical plug (1) having a plug housing (2) consisting of plastic and having at least one plastic-injection-moulded metal insert part (3, 4), which is provided therein and is exposed on at least one housing side (2a, 2b), according to the invention the plug housing (2) and the metal insert part (3, 4) are sealed off from one another by a cured sealing compound or adhesive compound (6), which is provided on the at least one housing side (2a, 2b) annularly around the exposed metal insert part (3, 4).