Why Surface Finish Is Important to Die Castings?
- Increase Corrosion Resistance: aluminium alloy has some corrosion resistance of its own, but it is still susceptible to corrosion in certain environments. Through electroplating, anodising and phosphating, they can provide additional corrosion resistance for castings and extend the service life.
- Finer Appearance: surface treatment improves the appearance of aluminum castings and makes them more attractive. This is important for the market appeal and decorative properties of products, especially in areas such as consumer goods, automotive parts and electronic devices.
- Improve Wear Resistance: hard anodizing or coating can improve the wear resistance of castings and extend their service life, especially in mechanical parts and engineering applications.
- Improve Lubricity: surface treatment can improve the lubricity of aluminum alloy castings and reduces frictional wear, resulting in improved performance and efficiency. This is important for applications such as machine parts and bearings.
- Improve Dimensional Stability: surface treatment can improve the surface flatness and dimensional stability of castings, ensuring that castings meet designed specifications and reducing the need for secondary processing.
- Excellent Adhesion: surface finishes can increase the adhesion of the coating or adhesive, ensuring that the coating layer will not be peeled off easily.
Sandblasting
- Working Principle: sandblasting is a mechanical surface treatment method that uses compressed air to spray abrasive particles onto the surface to be treated. These abrasive particles are impacted by high-speed airflow, scouring the surface and removing impurities and unevenness.
- Purpose: sandblasting is widely used to remove oxide layers, paint, rust, welding slag, dirt and other contaminants.
- Abrasives: sandblasting uses a variety of abrasives including sand, silicon carbide, alumina, steel shot, glass particles, etc. The choice depends on the desired surface quality and application requirements.
- Advantages: sandblasting is a cost-effective surface preparation method that removes dirt and unevenness in a relatively short period of time. It also increases surface adhesion, preparing it for subsequent coatings and surface treatments.
- Disadvantages: sandblasting can produce dust and waste, requiring proper ventilation and waste disposal. Additionally, for some precision parts, excessive material removal may occur, so operating parameters need to be carefully controlled.
Shot Blasting
- Working Principle: shot blasting is a surface treatment method that uses a high-speed shot blasting machine to project small metal particles onto the surface to be treated. These blasts remove dirt, oxide layers and unevenness with impact.
- Purpose: shot blasting is widely used to remove rust, prepare before spraying, improve the adhesion of metal surfaces, and increase the wear resistance of metal parts.
- Shots Choices: shot blasting can be steel shot, cast iron shot, ceramic shot, etc. The exact choice depends on the desired surface quality and application.
- Advantages: shot blasting is an efficient surface treatment method suitable for large parts and batch processing. It can quickly remove dirt and oxide layers, while improving adhesion and wear resistance.
- Disadvantages: similar to sandblasting, shot blasting may produce waste and requires proper ventilation and waste disposal. In addition, attention needs to be paid to controlling the parameters of the shot blasting machine to ensure that the required surface quality is achieved.
Spray Painting
- Working Principle: spray painting is a method of spraying paint or metal finishing paint onto the surface of aluminum alloy. This is usually done with compressed air, paint spray guns, or other spray equipment.
- Usage: spray painting is widely used to provide color, protection, decoration, coating or other special effects. It can be used to improve appearance, increase corrosion resistance, conductivity, insulation, and reduce friction.
- Coatings: coatings can be paints, powder coatings, varnishes or other special coatings, selected based on application requirements.
- Advantages: spray painting is a fast, economical and versatile surface treatment method that can be applied to a variety of aluminum casting parts and products.
- Disadvantages: spray painting may require multiple spraying and drying, and the coating thickness is difficult to control. The wear resistance is relatively low and may require periodic maintenance and respraying.
Anodizing
- Working Principle: anodizing is a method of forming an oxide layer on the surface of aluminum alloy through electrochemical methods. Aluminum alloy parts are served as anodes, and the current in the oxidizing solution passes through the parts to form an oxide layer.
- Purpose: anodizing can be used to improve hardness, wear resistance, corrosion resistance and decorative properties. It also improves coating adhesion.
- Oxidizing Solution: The oxidizing solution for anodizing usually includes sulfuric acid, oxalic acid, chromium sulfate, aluminum oxysulfate and other additives, the specific selection depends on the desired surface effect.
- Advantages: anodizing improves the hardness, wear resistance and corrosion resistance of aluminum castings. It can be made decorative by changing the color through the dyeing process.
- Disadvantages: anodizing is relatively thin and therefore not as wear-resistant as other treatments. The treatment process is complex and requires strict process control.
Electrophoresis
- Working Principle: electrophoresis is a method of depositing coatings onto the surface of workpieces through an electrochemical process. During the electrophoresis process, the workpiece is immersed in an electrolyte solution containing paint particles, and an electric current is applied to allow the liquid containing paint particles to migrate to the surface of the workpiece. The workpiece usually acts as cathodes, attracting positively charged paint particles.
- Usage: Electrophoresis is widely used in the automotive industry, home appliance manufacturing, metal furniture and other fields to provide uniform, high-quality anti-corrosion coatings. This method is also suitable for complex geometries and can be coated both internally and externally.
- Paints: Electrophoresis uses water-based paints that can be tinted or added color as desired. Water-based coatings are environmental friendly and suitable for using in a variety of industrial fields.
- Advantages: electrophoresis offers a cost-effective, environmental friendly coating method that coats surfaces internally and externally, providing high-quality protection and decoration.
- Disadvantages: electrophoretic coatings are relatively thin and therefore may not be as wear-resistant as other surface treatments. Strict control is required for operation and equipment to ensure uniform coating.
Surface Finish at CEX Casting
There are many different surface treatment technologies for die casting parts, and CEX Casting can provide most of them according to customer requirements, such as sandblasting, shot blasting, spraying, anodizing, electrophoresis, and other surface treatments.
We are committed to providing products with high-quality finishes to meet a wide range of needs, from improving corrosion resistance and adding decorative features to improving performance.
Below are some of our surface treated products.
FAQ
What Are the Purposes of Surface Finish?
Surface finish for aluminum casting parts serves various purposes including:
- Improving Corrosion Resistance
- Enhancing Appearance
- Providing Wear Resistance
- Facilitating Bonding or Adhesion
- Meeting Specific Functional or Decorative Requirements
What Are the Common Surface Finish Methods?
- Sandblasting
- Shot Blasting
- Spray Painting
- Powder Coating
- Anodizing
- Electrophoresis
Can Surface Finish Affect the Dimensional Accuracy?
Surface treatment methods such as anodizing and electroplating typically involve the deposition of a thin layer on the surface of the part, which generally has minimal impact on dimensional accuracy.
However, it is essential to consider any potential dimensional changes and account for them in the design and manufacturing process.
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