External Heat-Stake Collar for Increased Retention Force
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Solution Overview
Problem
The existing heat-staking process in the automotive industry faces challenges in achieving high retention force due to a small fastening surface area between the polymeric base member and the heat-stake's mushroom cap, especially when the polymeric base member is softer, leading to potential melting and reduced retention force.
Innovation Solution
A method involving a thermoplastic polymeric base member with a heat-stake collar that is heated to deform and surround the PALNUT or second member, increasing the contact area and retention force, allowing for a greater surface area engagement and optimized load transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a traditional heat-staking process is used with a small fastening surface, then the process is simple and quick, but the retention force is insufficient especially when the polymeric base member is softer
Solution Approach 1:
The heat-stake collar transitions from a linear/stake-like structure to a three-dimensional annular structure that surrounds the PALNUT® component. This dimensional change creates a circumferential contact area rather than a point or line contact, significantly increasing the fastening surface area and improving retention force.
Solution Approach 2:
The patent changes the physical state of the heat-stake collar by heating it to a temperature where it becomes deformable. This parameter change (temperature) allows the collar to be molded into an annular shape that maximizes contact area with the PALNUT® component, thereby increasing retention force.
2Stability of the object's composition
If heat is applied to the heat-stake leading end, then the material becomes deformable for joining, but the heat may melt the softer polymeric base member material reducing retention force
Solution Approach 1:
The heat-stake collar acts as an intermediary element between the heat source and the polymeric base member. By concentrating the heat application on the collar itself (which has sufficient thermal mass and conductivity), the heat is contained within the collar and does not transfer excessively to the softer polymeric base member, preventing unwanted melting.
Solution Approach 2:
The heating process is localized specifically to the heat-stake collar region rather than applying heat broadly to the entire assembly. This localized heating ensures that only the collar material reaches the deformable state needed for shaping, while the surrounding polymeric base member remains below its melting point.
3Strength
If the heat-stake collar is deformed to surround the PALNUT®, then the contact area and retention force increase, but the manufacturing process becomes more complex
Solution Approach 1:
The heat-stake collar is pre-formed with an annular cross-section and includes a pre-formed opening that accommodates the PALNUT® component. This preliminary shaping allows the collar to be inserted onto the PALNUT® before final heating and deformation, simplifying the overall process by pre-establishing the geometric relationship between components.
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 approach enhances the retention force and load transfer by increasing the contact area between the heat-stake collar and the PALNUT or second member, providing a stronger mechanical coupling and allowing for varied material compositions based on application-specific requirements.
Implementation Method 1
heating the heat-stake collar
Implementation Method 2
deforming a first end of the heat-stake collar to overlap or surround at least part of the PALNUT® (or the second member)
Data Source
AI summary
An external thermal heat-stake arrangement includes a polymeric base member having a collared heat-stake having an inner diameter and a second member disposed within the inner diameter of the collared heat-stake. The collared heat-stake is operatively configured to be deformed by a heated element to retain at least a portion of a peripheral edge of the second member to the polymeric base member.