Static Dewatering Element Coating for Web Forming Machines
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Solution Overview
Problem
Traditional dewatering elements for web forming machines, made from solid ceramic materials, are expensive and have high surface roughness and porosity, leading to issues like pit corrosion and fabric wear due to high porosity and surface roughness in existing coatings.
Innovation Solution
A static dewatering element with a thermally sprayed coating using agglomerates of primary particles smaller than 0.5 µm, such as chromium oxide or tungsten carbide, which reduces surface roughness and porosity to less than 0.3 µm and less than 1% respectively, improving durability and reducing fabric wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a thermally sprayed coating is applied using conventional powder particles, then the dewatering element can be manufactured at lower cost than solid ceramic, but the coating exhibits high porosity and surface roughness leading to pit corrosion and fabric wear
Solution Approach 1:
The invention changes the particle size parameter of the coating material to sub-micron range (0.1-0.5 μm), which fundamentally alters the coating morphology and density. This parameter change enables the coating to achieve low porosity and smooth surface finish while maintaining the cost advantage of thermal spray manufacturing over solid ceramic production
Solution Approach 2:
The invention uses composite coating materials consisting of metal matrix combined with ceramic particles or carbide particles. This composite structure provides both the adhesion and mechanical properties of metals and the wear resistance and chemical stability of ceramics, resolving the contradiction between manufacturability and durability
2Ease of manufacture
If a porous coating is used to reduce manufacturing cost, then the dewatering element can be produced more economically, but filler particles attach to the porous surface causing fabric wear
Solution Approach 1:
By changing the particle size parameter to sub-micron range and controlling the coating porosity to less than 1%, the invention creates a surface that is too smooth for filler particles to attach to. This eliminates the mechanism by which filler particles could cause fabric wear, while maintaining the economic advantage of thermal spray manufacturing
3Productivity
If a coating with high surface roughness is applied, then the thermal spray process is simpler and faster, but the fabric wear increases due to the rough surface
Solution Approach 1:
The invention changes the particle size parameter to sub-micron range (0.1-0.5 μm), which allows the coating to achieve extremely smooth surface finish (Ra < 0.3 μm) while still being applicable by thermal spray processes. This resolves the contradiction by showing that modern thermal spray technology can produce smooth surfaces with fine particles without sacrificing productivity
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 smoother, denser coating that is more cost-effective than solid ceramics, with enhanced corrosion resistance and reduced fabric wear, while maintaining wear resistance and improving manufacturing efficiency.
Implementation Method 1
Covering can be implemented by thermally spraying powder particles on top of the frame layer. The coating can be sprayed thermally using, for example, plasma or high-speed flame spraying methods.
Implementation Method 2
The aluminum profile is covered with an oxide layer provided by electrolytic plasma oxidation or spray explosion covering, for example.
Implementation Method 3
The aluminum profile is covered with an oxide layer provided by electrolytic plasma oxidation or spray explosion covering, for example.
Data Source
Figure 1~2
Figure 3a~4b
Figure 5~6
AI summary
The invention relates to a static dewatering element f or a web forming machine. The dewatering element (10) has a thermally sprayed coating (26) manufactured of powder particles (34). The powder particles (34) are agglomerates composed of primary particles (36). The average size of the primary particles (36) is smaller than 0. 5 µm. The invention also relates to a method f or covering a static dewatering element designed for a web forming machine.