Corrosion Resistant Bushing Edge Coating Method
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Solution Overview
Problem
There is a need for maintenance-free bushings with improved corrosion resistance and longer lifespan in both automotive and non-automotive applications, as existing sliding bearing composite materials do not adequately address corrosion issues.
Innovation Solution
A method of forming a corrosion-resistant bushing involves cutting a laminate sheet with a sliding layer bonded to a load-bearing substrate, applying a corrosion-resistant coating to the exposed surfaces and cut edges, and using a combination of temporary corrosion protection layers, adhesion promoters, and an epoxy layer to enhance corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sliding bearing composite material is used without additional corrosion protection, then the manufacturing process is simple, but the corrosion resistance is insufficient and maintenance-free lifetime is reduced
Solution Approach 1:
The corrosion protection system is segmented into three distinct functional layers: a temporary corrosion protection layer applied to the load bearing substrate before laminating, a permanent corrosion protection layer applied to exposed surfaces after forming, and adhesion promoters at interfaces. This segmentation allows each layer to be optimized for its specific function while maintaining overall system manageability.
Solution Approach 2:
The temporary corrosion protection layer is applied to the load bearing substrate before the sliding layer is bonded to it. This preliminary action ensures corrosion protection is in place during manufacturing and assembly, and the layer is later removed only where it interferes with the permanent corrosion protection coating application.
2Reliability
If the temporary corrosion protection layer is not removed from cut edges, then the manufacturing process is simpler, but the adhesion of the permanent corrosion protection coating is poor
Solution Approach 1:
The temporary corrosion protection layer is selectively removed only from the cut edges and surfaces that will receive the permanent corrosion protection coating, while being retained on other portions of the load bearing substrate. This local quality approach ensures optimal adhesion where needed while maintaining the benefits of temporary protection elsewhere.
Solution Approach 2:
An adhesion promoter layer is applied as an intermediary between the temporary corrosion protection layer and the permanent corrosion protection coating at the cut edges. This intermediary layer facilitates strong bonding between the permanent coating and the substrate, even when the temporary layer is partially retained.
3Duration of action of stationary object
If dissimilar metals are allowed to contact each other, then the bushing structure is simpler, but galvanic corrosion occurs reducing lifespan
Solution Approach 1:
The permanent corrosion protection coating serves as an intermediary barrier layer between dissimilar metals (such as the load bearing substrate and fasteners or housing). This intermediate layer prevents direct galvanic contact while maintaining the structural simplicity of the bushing design.
Solution Approach 2:
The corrosion protection system uses composite material structures with multiple layers having different properties: the temporary corrosion protection layer provides initial protection, the adhesion promoter ensures bonding, and the permanent corrosion protection coating provides long-term galvanic and environmental protection. This composite approach extends maintenance-free lifetime while managing complexity.
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 method significantly increases the corrosion resistance of bushings, preventing contact between dissimilar metals and corrosive elements, thereby extending the maintenance-free lifetime by achieving a Corrosion Resistance Rating of at least 120 hours, as demonstrated by neutral salt spray tests.
Implementation Method 1
an adhesion promoter layer between the temporary corrosion protection layer and the load bearing substrate
Implementation Method 2
applying a corrosion resistant coating to the exposed surface and the load bearing substrate portion of the cut edges
Data Source
Figure 1~2
Figure 3A~3F
Figure 4~5
AI summary
A method of forming a corrosion resistant bushing includes bonding a sliding layer to a first surface of a load bearing substrate to form a laminate sheet and cutting a blank from the laminate sheet. The laminate sheet includes an exposed surface corresponding to a second surface of the load bearing substrate. The blank includes cut edges having a load bearing substrate portion. The method further includes forming a semi -finished bushing from the blank, and applying a corrosion resistant coating to the exposed surface and the load bearing substrate portion of the cut edges to form the corrosion resistant bushing.