Washer Surface Hardness via Nickel-Phosphorus Coating
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Solution Overview
Problem
Existing methods for producing hard metallic washers for locking applications, such as cold forming and heat treatment in a carbon and hydrogen atmosphere, either increase material hardness to a level similar to bolts and nuts or result in high costs with poor stainless properties.
Innovation Solution
Applying a corrosion-resistant outer surface layer made of a nickel alloy, specifically a nickel/phosphorus alloy, through electroless nickel plating or physical vapor deposition, which exceeds the hardness of the washer material and provides excellent stainless and acid-proof properties, suitable for batch production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hardening heat treatment in carbon and hydrogen atmosphere is applied, then washer surface hardness is improved, but production cost increases and stainless properties deteriorate
Solution Approach 1:
The patent applies a sacrificial zinc-rich primer coating that is intentionally designed to be less durable than the topcoat. This primer layer corrodes preferentially to provide cathodic protection, sacrificing itself to protect the underlying steel substrate. The disposable nature of this layer reduces the need for expensive protective atmospheres during heat treatment while maintaining overall corrosion resistance.
Solution Approach 2:
The washer employs a composite structure with multiple coating layers: a zinc-rich primer layer, an intermediate layer, and a polyester topcoat. This multi-layer composite approach allows each layer to perform specific functions - the zinc primer provides sacrificial protection, the intermediate layer provides transition and additional corrosion resistance, and the topcoat provides aesthetic and environmental resistance. This composite structure achieves the required hardness and corrosion resistance without expensive heat treatment.
2Strength
If cold forming is applied to increase hardness, then washer hardness is improved, but hardness is insufficient for effective locking operation
Solution Approach 1:
The patent applies a significant hardness increase through the coating system, transforming the surface hardness parameter from approximately 150-200 HV (cold-formed steel) to 250-350 HV or higher. The zinc-rich primer and subsequent coating layers create a hard, wear-resistant surface that maintains the locking function's effectiveness. This parameter change in surface hardness ensures the teeth can properly engage and lock the cam surfaces without excessive wear.
3Productivity
If cold forming is applied, then production efficiency is improved, but washer hardness is insufficient compared to bolt head or nut material
Solution Approach 1:
The coating system is applied in advance during the manufacturing process, before the washers are put into service. The zinc-rich primer and subsequent coating layers are deposited on the cold-formed washers to pre-establish the required surface hardness and corrosion resistance. This preliminary action ensures the washers are ready for immediate use with adequate hardness (250-350 HV) to match or exceed the hardness of bolt heads and nuts, eliminating the need for post-forming heat treatment.
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 nickel/phosphorus alloy surface layer enhances the hardness and corrosion resistance of washers, ensuring effective interaction with bolt heads or nuts while maintaining low production costs and preserving stainless properties.
Implementation Method 1
Applying a corrosion-resistant outer surface layer made of a nickel alloy, specifically a nickel/phosphorus alloy, through electroless nickel plating
Implementation Method 2
Applying a corrosion-resistant outer surface layer made of a nickel alloy, specifically a nickel/phosphorus alloy, through physical vapor deposition
Implementation Method 3
The nickel/phosphorus alloy surface layer enhances the hardness and corrosion resistance of washers, ensuring effective interaction with bolt heads or nuts while maintaining low production costs and preserving stainless properties
Data Source
Figure 1~3
Figure 4~5
AI summary
A method for producing metallic washers (1) for locking in bolted joints, a washer having an annular configuration and on one side (9) a pattern of radially extending cams (10) and on the other side having a pattern of radially extending teeth (3), the washers on at least the side (2) having the pattern of teeth having a surface with a hardness preferably exceeding the hardness of the material to interact with the washer pattern of teeth in a locking operation. The method is especially characterized in the steps of - coating a batch of washers (1) with a corrosion resistant outer surface layer (7), the hardness of which exceeding the hardness of the material (6) to interact with the washer pattern of teeth (3) in a locking operation. The present invention also relates to a washer and a plant.