Sealed Fastener Cap With Segmented Moisture Barrier
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Solution Overview
Problem
Existing fastener cap systems fail to effectively prevent moisture infiltration, leading to issues like rot, mold, mildew, and fastener corrosion, as they often rely on inadequate sealing methods that can trap or wick moisture, causing damage to underlying structures.
Innovation Solution
A fastener cap system featuring a rigid cap with a sealing member that forms a liquid barrier around the cap and fastener, utilizing a central seal disc and secondary seal ring to prevent moisture entry, and a method of manufacturing that includes co-molding or co-extruding polymeric and elastomeric materials to create a monolithic unit with enhanced sealing properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a flat rubber washer is placed under the fastener head to seal, then moisture penetration is reduced, but the rubber washer acts as a wick to draw moisture toward the fastener shaft
Solution Approach 1:
The sealing member is divided into multiple functional zones: an outer seal rim that contacts the substrate to prevent moisture entry under the cap, and an inner seal disc that seals around the fastener shaft. This segmentation prevents continuous moisture pathways and eliminates the wicking effect by creating discontinuous seal zones rather than a single continuous rubber washer.
Solution Approach 2:
The sealing member acts as an intermediary barrier between the external environment and the fastener system. It intercepts moisture at two locations (outer rim and inner disc) to prevent it from reaching the fastener shaft, thereby mediating the moisture protection function without creating wicking pathways.
2Object-affected harmful factors
If a rupture-able receptacle filled with liquid sealant is placed under the cap, then sealing is improved, but the receptacle can break before installation creating a mess
Solution Approach 1:
The sealing member is designed as a pre-formed, single-use component that is disposed of after installation. It provides reliable sealing without the risk of premature rupture during handling, as it is not a contained reservoir but a structural seal element integrated with the cap.
Solution Approach 2:
The sealing member is pre-formed and pre-positioned on the cap before installation, eliminating the need for rupture-able receptacles. The seal is ready to function immediately upon installation, providing preliminary sealing action without the reliability issues of stored liquid sealant.
3Object-affected harmful factors
If the sealing member extends under the central cap disc to the fastener shaft, then moisture seal is improved, but moisture can still wick toward the fastener through the sealing member
Solution Approach 1:
The sealing member is segmented into an outer seal rim and an inner seal disc with a discontinuous configuration. The inner seal disc does not extend continuously to the fastener shaft, creating a gap that prevents capillary wicking while still providing a seal barrier. This segmentation breaks the continuous pathway that would otherwise allow moisture to wick to the fastener.
Solution Approach 2:
The sealing member provides different sealing qualities at different locations: the outer seal rim provides a robust seal against substrate, while the inner seal disc provides a lighter seal around the fastener shaft area. The local quality varies to prevent over-sealing that would create wicking pathways while maintaining adequate protection.
Data Source
AI summary
A fastener cap system can include a rigid cap and a sealing member which forms a liquid barrier so moisture is impaired from entering a space under the rigid cap and/or around a fastener installed through it. The sealing member can include a central seal disposed on an upper surface of the cap, the seal extending beyond a head of a fastener, which extends through the cap and sealing member, so that moisture is impaired from entering the cap under the head. The sealing member can be above and below respective lowermost and uppermost cap surfaces so the cap system can be fed cleanly and efficiently through a cap feeder during installation via a tool. The sealing member, which can have a higher coefficient of friction than the rigid cap, thereby does not drag along a cap feeder and cause feeding issues. Related methods of manufacture and use are provided.