Dishwasher Wash Container Material Mix for Cost and Corrosion Control
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Solution Overview
Problem
The high material costs of austenitic stainless steel used in dishwasher washing compartments due to its high nickel content, combined with the limitations of ferritic steels in deformation and weldability, pose a challenge in reducing production costs while maintaining formability and corrosion resistance.
Innovation Solution
The use of a heterogeneous combination of metallic materials with varying austenite former content, where austenitic steel is used for deformable areas and ferritic steel for non-deformable areas, along with a plastic seal or passivation to prevent corrosion, and the implementation of a sacrificial or impressed current anode for additional protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If austenitic stainless steel with high nickel content is used for the wash container, then formability and weldability are improved, but material cost increases
Solution Approach 1:
The patent applies different metallic materials to different areas of the wash container based on local requirements. Austenitic stainless steel is used in areas requiring high formability and weldability, while ferritic stainless steel is used in areas where these properties are less critical, thereby optimizing material cost while maintaining manufacturing capability where needed
Solution Approach 2:
The patent employs a composite structure combining multiple metallic materials (austenitic and ferritic stainless steels) within the same wash container. This composite approach allows the container to benefit from the superior formability and weldability of austenitic steel in critical areas while using cost-effective ferritic steel in other areas, resolving the contradiction between manufacturing ease and material cost
2Quantity of substance
If ferritic steel is used to reduce material cost, then material cost decreases, but formability and weldability deteriorate
Solution Approach 1:
The patent strategically places ferritic stainless steel in areas of the wash container where high formability and weldability are not critical requirements, thereby achieving cost reduction without compromising the manufacturability of critical components. The austenitic steel is reserved for areas requiring extensive forming operations or welding
3Quantity of substance
If different metallic materials are used in the wash container, then material cost is optimized, but corrosion resistance deteriorates due to crevice corrosion
Solution Approach 1:
The patent introduces a plastic seal as an intermediary element at the junction areas between different metallic materials. This plastic seal prevents direct contact between dissimilar metals, eliminating the electrochemical cell formation that causes crevice corrosion, while still allowing the cost-optimized heterogeneous material structure to be implemented
Solution Approach 2:
The patent acknowledges the potential harm of using different metallic materials (corrosion risk) but converts this challenge into a benefit by using the junction areas between materials as locations for applying protective measures such as plastic seals or passivation treatments, thereby enhancing overall corrosion protection while maintaining material cost optimization
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 reduces material costs by optimizing metal selection for specific processes, ensures formability and weldability in critical areas, and effectively prevents corrosion through sealing and passivation, thereby maintaining the integrity and longevity of the washing compartment.
Implementation Method 1
To prevent corrosion defects, especially crevice corrosion, it is stipulated that a plastic seal is applied to at least one junction area between the at least two different metallic materials
Implementation Method 2
The passivation prevents diffusion, thus halting the progression of corrosion in the material
Implementation Method 3
the chromium forms a chromium oxide layer that prevents further oxidation
Implementation Method 4
the passivation is self-healing
Implementation Method 5
the sacrificial anode and the metal with the higher content of austenite-forming minerals form a local cell. Over time, the sacrificial anode slowly dissolves, thus protecting the more noble metal, i.e., the metal with the higher content of austenite-forming minerals, from corrosion
Implementation Method 6
A protective current is established, which prevents electrochemically induced corrosion
Data Source
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AI summary
The invention relates to a method for manufacturing a water-bearing domestic appliance, in particular a dishwasher or washing machine, at least having a washing container for accommodating the items to be washed, said washing container being formed at least in portions from metal materials, in particular from stainless steel. The invention is characterized in that at least two different metal materials are used to form the washing container.