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Explanation of screw surface treatment: Methods and examples for improving rust prevention and durability
Introduction
Screws are essential components that play an active role in every aspect of our daily lives and various industries. However, even these small screws can rust or wear out depending on the environment in which they are used. This is where “surface treatment” becomes crucial.
This article explains why screw surface treatment is important, what types are available, and how to choose the right one. We hope to deepen your knowledge of screw surface treatment and help you create safer and longer-lasting products.
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Types and Methods of Surface Treatment
There are various types and methods of screw surface treatment. Let’s take a closer look at the representative ones.
Plating Treatment
Plating is a method of forming a thin film of another metal on the surface of a metal.
- Electroplating: A method that deposits metal using electrolysis, capable of forming a relatively thin film. Suitable for small parts.
- Electroless Plating: A method that deposits metal using chemical reactions without electricity, making it applicable to non-metal materials as well.
- Hot-Dip Plating: A method of plating by immersing the part in molten metal, offering excellent cost performance.
Zinc Plating
This method enhances corrosion resistance by coating a steel substrate with zinc.
- Features and Applications: Offers good cost performance and is suitable for corrosion protection in outdoor environments. Protects iron through sacrificial corrosion. Widely used in construction and civil engineering fields.
- Advantages/Disadvantages: While highly durable, its durability decreases in high-temperature environments.
Hot-Dip Galvanizing
This method forms a thicker zinc layer than regular zinc plating, offering very high corrosion protection performance.
- Features and Applications: Prevents the ingress of oxygen and moisture, demonstrating high durability. Suitable for infrastructure facilities and large buildings.
- Advantages/Disadvantages: While highly durable, it is not suitable for precision parts.
Nickel-Zinc Plating
This method enhances corrosion resistance and wear resistance by adding nickel to the zinc layer.
- Features and Applications: Exhibits high durability even in environments with salt damage and many chemicals.
- Advantages/Disadvantages: While having high corrosion resistance and wear resistance, costs can be higher.
Trivalent Chromate Treatment
An environmentally friendly treatment method that offers excellent corrosion resistance and durability.
- Features and Applications: Allows for various color tones and is widely adopted in automotive, construction, and electronic devices. Also complies with the RoHS Directive.
- Advantages/Disadvantages: While environmentally friendly, process control is crucial.
Other Surface Treatments
- Black Oxide Treatment (Parkerizing): A chemical treatment method that forms a ferrous ferric oxide film. Its rust-preventive power is weak, and it is mainly used for decorative purposes or as a pretreatment for painting.
- Nickel Plating: A treatment that improves corrosion resistance and wear resistance. Also suitable for applications where aesthetics are important.
- Chrome Plating: A treatment that improves wear resistance and heat resistance. Used in environments requiring high durability.
- Dacromet Treatment: A non-electrolytic treatment method that enhances corrosion resistance. Particularly suitable for high-strength screws.
- Painting: A method of applying paint to improve rust resistance and aesthetics. Used in outdoor environments or environments exposed to chemicals.
Advantages and Disadvantages of Surface Treatment
Screw surface treatment offers many benefits, but also comes with some disadvantages. Here, let’s take a closer look at both aspects.
Advantages
- Improved Corrosion Resistance: The biggest advantage of surface treatment is that it enhances the corrosion resistance of screws. It protects screws from rust and corrosion, extending product life. Especially for screws used outdoors or in humid environments, anti-corrosion treatment is indispensable.
- Improved Wear Resistance: Surface treatment can increase the surface hardness of screws and suppress deterioration due to wear. This improves the durability of screws, allowing them to withstand long-term use.
- Improved Aesthetics: Surface treatment also has the effect of giving screws a beautiful finish. It is utilized to enhance product design, such as glossy plating or colored coatings.
- Added Functionality: Depending on the surface treatment, it is also possible to add specific functionalities to screws. For example, making them water-repellent or electrically conductive can improve product performance.
Disadvantages
- Increased Cost: Surface treatment increases the manufacturing cost of screws. Costs tend to be higher especially when advanced treatments or special materials are used.
- Film Thickness Variation: In surface treatments such as plating or painting, the film thickness may not be uniform. Especially in complex shaped parts such as screw corners and grooves, film thickness tends to vary, which can affect corrosion protection and aesthetics.
- Durability Limit: Although surface treatment is intended to improve the durability of screws, it is not permanent. Depending on the usage environment and conditions, the surface treatment may deteriorate and lose its original effect. Therefore, regular maintenance or replacement may be required.
Specific Examples
Screw surface treatment contributes to improving product performance in various fields. Here are some specific examples.
- Use of Hot-Dip Galvanizing in Construction and Civil Engineering: In construction and civil engineering sites, screws are often used outdoors and are exposed to environments prone to rust and corrosion. Therefore, hot-dip galvanizing, which has high corrosion resistance, is widely used. A thick zinc layer protects the screws, supporting the safety of structures over a long period.
- Adoption of Trivalent Chromate Treatment and Nickel-Zinc Plating in Automotive Parts: Automobiles are exposed to various environmental conditions during driving, making the durability of parts extremely important. Screws are no exception, and trivalent chromate treatment and nickel-zinc plating, which offer excellent corrosion resistance and wear resistance, are adopted. These treatments improve the safety and reliability of automobiles.
- Use of Chrome Plating in Electronic Devices: Electronic devices are composed of precise parts and require aesthetic appeal. Chrome plating not only offers excellent corrosion resistance and durability but also achieves a glossy and beautiful finish, making it used for screws in electronic devices.
- Improved Hygiene with Fluorine Coating in Food Equipment: In equipment handling food, hygiene management is extremely important. Applying fluorine coating to screws can achieve a surface that is resistant to dirt and easy to clean. This improves the hygiene of food equipment and supports safe food production.
- Highly Weather-Resistant Painting for Construction Screws: Construction screws are often used outdoors and are therefore exposed to natural environments such as UV rays and rain. Therefore, screws with highly weather-resistant paint are used. This prevents the deterioration of screws and maintains the aesthetics and safety of buildings.
As these examples show, screw surface treatment is a crucial factor that greatly affects product performance and lifespan.
How to Choose Screw Surface Treatment
When choosing screw surface treatment, several important factors need to be considered. Here, we explain the key points for selecting the optimal surface treatment.
- Usage Environment: The environment in which the screw will be used significantly influences the selection of surface treatment. It is necessary to choose the appropriate treatment according to environmental conditions such as outdoor use, humid places, or exposure to seawater. For example, for outdoor use, hot-dip galvanizing or painting with excellent weather resistance and rust prevention is suitable.
- Balance of Cost and Performance: Each surface treatment has a different cost. It is important to consider the balance between required performance and budget to choose the optimal treatment. An expensive treatment is not necessarily the best.
- Required Functionality: The functionality required of the screw also affects the choice of surface treatment. Choose the appropriate treatment according to the required functionality, such as wear resistance, water repellency, or electrical conductivity. For example, for areas where frequent tightening and loosening occur, chrome plating with excellent wear resistance is suitable.
- Balancing Aesthetics and Durability: The appearance of the screw can also be an important factor. Consider plating or colored coatings to achieve both aesthetics and durability. For example, nickel plating or trivalent chromate treatment is suitable for areas where decorative properties are required.
- Material Type: The applicable surface treatment differs depending on the screw’s material. It is important to choose a treatment suitable for the material, such as metal or resin. For example, anodizing is suitable for aluminum screws.
- Compliance with Environmental Regulations: In recent years, compliance with environmental regulations has also become an important factor. Choose surface treatments that comply with environmental regulations such as the RoHS Directive. For example, trivalent chromate treatment, which does not contain hexavalent chromium, is recommended.
By considering these points, you can select the optimal surface treatment that matches the screw’s usage environment and purpose.
Important Considerations
When performing screw surface treatment, there are several important considerations. By taking these into account, you can achieve higher quality products.
- Response to Dimensional Changes: Surface treatments such as plating or painting may cause changes in screw dimensions. Especially for precision parts or mating parts, dimensional changes can negatively affect product performance. It is important to consider dimensional changes at the design stage and set appropriate tolerances.
- Importance of Film Thickness Control: If the film thickness of the surface treatment is not uniform, it can adversely affect corrosion protection and aesthetics. Especially in complex shaped parts such as screw corners and grooves, film thickness tends to be uneven. It is important to use appropriate treatment methods and process control to maintain uniform film thickness.
- Durability Limit and Maintenance Plan: While surface treatment is intended to improve screw durability, it is not permanent. Depending on the usage environment and conditions, the surface treatment may deteriorate and lose its original effect. Regular maintenance or replacement may be required. It is important to consider the durability limit and establish an appropriate maintenance plan.
- Importance of Process Control: The quality of surface treatment is greatly influenced by process control. Various factors such as treatment temperature, treatment time, and treatment solution concentration affect quality. It is important to perform appropriate process control and ensure quality stability.
Summary
This article explained the importance, types, selection methods, and considerations for screw surface treatment.
Choosing the optimal surface treatment is crucial for enhancing product performance, lifespan, and safety. Comprehensively consider the usage environment, cost, and required functionality to select the best treatment.
Moving forward, it is expected that higher-performance and more environmentally friendly surface treatments will be developed with technological advancements. Let’s deepen our knowledge of screw surface treatment and contribute to creating better products.
Finally
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