What is surface treatment?
Surface treatment is an additional process applied to the surface of a material for the purpose of adding functions such as rust and wear resistance or improving the decorative properties to enhance its appearance.
Painting, such as that applied to the body of an automobile, printing of the manufacturer's name and other information on the surface of home appliances, and "plating" applied under the paint on guardrails, are typical examples of surface treatment.
Heat treatment, such as quenching, applied to metal parts such as gears and blades, is also classified as surface treatment.
Surface treatments can be broadly classified into removal processes, such as scraping or melting the surface, and additive processes, such as painting, which add something else to the surface.
Methods of surface treatment
The most commonly used surface treatments include the following methods. Surface treatments that use electricity and require a dedicated power supply are indicated in red letters in the table.
| Category | Process | Explanation |
|---|---|---|
| Cleaning | Cleaning | Cleaning is a process to remove oil, surface oxides, burrs and foreign substances. It can prolong the life of painting and plating. Among the cleaning processes, blasting and honing use abrasives and grinding wheels, respectively, so these processes can be said to be both cleaning and polishing. |
| Blasting | ||
| Honing | ||
| Polishing | Mechanical polishing |
Polishing the surface to make it smooth. While polishing is generally associated with rubbing with a grinding stone or brush, chemical or electropolishing slightly dissolves the surface to make it smooth. Electropolishing uses electrolysis to dissolve the surface of the part in a solution. |
| Chemical polishing | ||
| Electropolishing | ||
| Painting | Spray painting |
This is the process of adding paint to a surface. This is done to improve corrosion resistance and decorative properties. Electrostatic coating is a type of coating in which the paint is charged and adheres efficiently with the force of static electricity. Powder coating is also a type of electrostatic coating. Electrodeposition coating is a method of depositing paint on the surface of a part by electrolysis of a solution of special paint and is used for the base of automobile bodies. |
| Electrostatic coating (Electrostatic painting) | ||
| Electrodeposition coating | ||
| Plating | Electroplating (electrolytic plating) |
Plating is the process of covering the surface of a component with a thin film of another metal. Electroplating is a method of depositing a coating on the surface of a part by electrolyzing a solution. This is mainly done on metals such as iron to provide corrosion resistance and decorative properties. In some cases, plating is applied to the surface of plastics for decorative purposes, but the number of such applications has been decreasing in recent years due to improvements in coating technology. |
| Chemical plating | ||
| Hot dip coating | ||
| Heat treatment | Surface quenching | This is a treatment that hardens the surface of metals to improve their resistance to wear and fatigue. By heating and cooling the metal, the structure of the metal surface is changed, making it harder. In surface quenching, there is a method called high-frequency quenching, in which a high-frequency current is applied to a coil, heating the part in the manner of a so-called induction heater. |
| Carburizing | ||
| Nitriding treatment |
Surface treatment process
There are several types of surface treatment, but here we will use plating as an example and explain electrolytic plating. There are several types of electrolytic plating: gold, silver, copper, nickel, zinc, and chrome.
- 1 Pre-work
- Barrel polishing is performed to remove burrs from the product, and the jig for plating (a tool to hold the product to be plated and make it easier to work with) is attached.
- 2 Pretreatment
- Chemical treatments such as alkaline degreasing, pickling, electrolytic cleaning, and acid activation are used to prepare the material for plating.
- 3 Plating
-
The material is immersed in the plating bath while still attached to the jig and then plated by energizing. Electrolytic plating utilizes the mechanism that when an electric current is passed through a solution containing metal ions, the metal is deposited on the cathode side by electrolysis.
By inserting a material to be plated with a cathode electrode and an anode electrode into the plating solution and passing an electric current through them, metal is deposited on the surface of the material to be plated, forming a plating film. Depending on the base material and the type of plating, multiple layers of plating are applied, including base plating.
- 4 Post-treatment
- Chromate treatment, discoloration prevention, drying, etc. are performed to stabilize the plating, and the plating solution is neutralized.
- 5 Post-processing
- The plated material is removed from the jig and undergoes a baking process. This step is crucial for hydrogen embrittlement relief--removing absorbed hydrogen to prevent the material from cracking or becoming brittle.
Advantages of Electrolytic Plating
Electrolytic plating offers several key benefits:
- Cost-effective processing
- High-gloss decorative finishes
- Enhanced corrosion resistance
- High deposition speed
- Compatible with a wide variety of metals and alloys
- Minimal thermal impact on the base material
The Role of Power Supplies in Surface Treatment
Surface treatment technologies are essential across various industries. Electrolytic plating, in particular, continues to expand its applications, driving the demand for high-quality and cost-effective processing.
Electrolytic plating relies on electrolysis, which requires a precise Direct Current (DC) power source. Voltage stability and low ripple are critical factors; unstable output can lead to uneven deposition, directly affecting the quality and durability of the finished product.
Additionally, plating thickness is proportional to the integrated current (current x time). Therefore, power supplies must offer precise current control and high efficiency to ensure consistent results.
Operating environments for plating are often harsh due to corrosive gases and high humidity. Consequently, power supplies must be engineered with high environmental resistance or designed for easy integration into isolated control systems.
To address these challenges, Matsusada Precision offers a lineup of high-performance DC power supplies optimized for electroplating applications. Our products ensure the stability and reliability required for demanding surface treatment processes.
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