Aluminum die casting surface finishing has multi- methods on surface of casting parts. Depends on the applications and functions of aluminum die casting part, they can be had some proper surface finishings, which extends the aluminum die casting part life time and durability. These surface finishing options, Include of powder coating, painting, polishing, plated,anodizing, sandblasting and chromate conversion coating etc. These die casting parts surface finishes are decided by die castings surface finish design and client’s requirements.
Why Surface Finishing Matters for Aluminum Die Castings
Aluminum alloys used in die casting (such as ADC12, A380) offer excellent lightweight properties, but in some special conditions,the aluminum cast parts require surface finishing treatments to meet the demand of functionality and applications. The surface finishing helps aluminum die castings much more.
Corrosion & Wear Resistance Enhancements
Die casting parts require further surface finishing to enhance corrosion & wear resistance and prolong its life time and better luxurious appearance. The metal cast parts maybe plating, painting and powder-coating, all are decide by functions and application environment. Whenever zinc die cast part or aluminum die cast one, required coating option will enhance its corrosion and wear resistance.
Enhanced Component Appearance Aesthetics
Some luxurious appearance metal parts are used as fashion accessories and gifts or decorative trims. These metal parts need glossy and luxurious appearance aesthetics. People improve the metal parts appearance by plating or coating options. So aluminum die casting surface finishing is essential for enhancing component appearance aesthetics.
Prolong The Life Time Of Die Castings
Suface finishing options can prolong die castings life time, because the coating layer isolates continuous oxidation from air, prevents the surface of cast part is corroded from oxygen. So the surface finishing option can make the die casting part remain strong surface and corrosion resistance, aim to prolong the life time of the part.
Minimal Porosity & Defects
Suface finishing options can cover the thin layer on the surface of the cast part evenly, and fill the porosity and defects on the surface of the part, and create a smooth surface. For example, alumimun alloy is porosity metal, the aluminum die casting requires the treatment of impregnation to reach good result for striking metal bonding.
Enhanced Specific Functionalities
Sometimes, the cast part require some metal coating to enhance the electricity conductive property and decoration result. Like some touch points of specific switches, which have a superious electrical conductivity or some accessories and decorative appearance for fashions and bags.
Common Aluminum Die Casting Surface Finishing Methods
Aluminum die casting surface finishing can improve appearance. While diversity surface finishes for die castings, which need proper secondary processes. They involve of polishing, power-coated, plated, anodized, painting, sandblasting and chromate conversion coating etc. As the follow options that Ts die casting technology works.
Plating
Surface finishing options for electroplating are diversity, such as chrome, nickel and zincto plated. Aluminum die castings plating is special surface finishing. Firstly The die casting part deburring process is conducted, removing the excess material on the cast parts. maintain smooth surface finish.
Then these treated aluminum parts should be have an impregnation process to improve porosity status on the suface of aluminum die castings. The resin impregnation seal the porosity of the surface of cast part, then zin plated striking is done and create adhesive layer for electroplating material. At last , nickel and chrome plating on them.
Painting or Powder-Coating
Painting or powder coating finish means coating a protective or decorative layer of paint or polymer powder on the surface of the part. As die casting parts , Coating paint and powder on aluminum die casting parts can enhance durability of the castings and decorative appearance.
Anodizing
Anodizing is an electrochemical process, which is very suitable for aluminum die castings. These parts are immersed in a tank filled with an electrolyte solution, though chromic and phosphoric acid are used for specific applications. A current is passed through the acid. This causes oxygen ions to be released from the electrolyte. It allows for coloring, and Sattin and matte effection. Like some automotive components aluminum die casting.
Sandblasting / Shot Blasting
Sandblasting or shot blasting can remove the oxides and containments on the surface of aluminum cast part, create uniform matte finish and improve coating adhesion. Some hidden burrs are removed by high pressure tiny sand particles. So some medium and small sized cast parts are often treated on the way before painting and powder-coating.
Chromate Conversion Coating
The chemical coating forms a protective film on the metal cast parts, it has a good corrosion resistance, maitain good electrical conductivity. The aluminum die castings are lightweight and strong strength, and treated by chromate conversion coating, they can be used for automotive, aerospace fields.
The above the surface finishing options for aluminum die casting protect the aluminum parts and prolong the life of part and improve the apperance of the part in high-efficiency envenly.
Key Design Considerations for Aluminum Die Casting Surface Finishing
Experience told us that implementing the below measurements to prevent and reduce failure for aluminum surface finishing . For porous aluminum cast parts, our expert suggest manufacturers to have good impregnation technology to treat them. Of cource Consider of the below key design factors for aluminum die casting surface finishing.
1. Control Porosity
Porosity is a major issue in aluminum die casting. Engineers take some proper measurements to improve porous surface of the aluminum cast parts. The effective methods can improve and optimize the cast part surface finishing well.
- Optimize die casting parameters
- Use vacuum die casting
- Apply impregnation if needed
2. Surface Roughness (Ra)
Different finishes require different roughness levels. Depends on the requirement demands for the aluminum part, which surface roughness is treated correctly, Coating thickness decides the surface roughness required directly. The common coatings are the below.
- Anodizing: Ra ≤ 1.6 μm recommended
- Polishing: Ra ≤ 0.8 μm
- Powder coating: less strict
3. Alloy Selection Matters
Different alloys behave differently, because different aluminum alloy, different metal element content, and create different metal properties. Such as strength, hardness, wear resistance, corrosion resistance and mechanical process properties. So different type aluminum cast part allows different surface finishing.
- A380: good castability, moderate finishing quality
- ADC12: widely used, cost-effective
- High-purity aluminum: better for anodizing
4. Pre-treatment is Critical
Aluminum die casting part should be pre-teated before surface finishing, like mechanical processing, degreasing, removing containment and dirt and acid cleaning. This enhances material adhesion and surface uniform smoothness.
Comparison of Aluminum Surface Finishes
The below table show a balance for aluminum surface finishes, from surface finishing approaches, durability, appearance and typical use.
| Process | Corrosion Resistance | Cost | Appearance | Durability | Typical Use |
|---|
| Anodizing | ⭐⭐⭐⭐☆ | Medium | Excellent | High | Electronics |
| Powder Coating | ⭐⭐⭐⭐⭐ | Medium | Wide colors | High | Outdoor use |
| Electroplating | ⭐⭐⭐⭐☆ | High | Metallic | Medium | Decorative |
| Polishing | ⭐⭐☆☆☆ | Low | Smooth | Low | Pre-treatment |
| Sandblasting | ⭐⭐☆☆☆ | Low | Matte | Low | Surface prep |
| Chromate Coating | ⭐⭐⭐☆ | Low | Industrial | Medium | Aerospace |
Conclusion
Aluminum die casting surface finishing can either extend the life time of these parts or improve parts appearance esthetics. Because advantages of aluminum die casting surface finishing is obvious, which includes Corrosion & Wear Resistance Enhancements, Enhanced Component Appearance Esthetics, Prolong The Life Time Of Die Castings and Enhanced Specific Functionalities. The professional die casting factory works with various aluminum die casting surface finishing options, create high quality aluminum cast part coated for clients.
