Characteristics of Aluminum Alloy Die Casting Products
1. Classification of Aluminum Alloys: Aluminum alloys can be divided into four types based on their performance and uses: LF (rust-proof aluminum), LY (hard aluminum), LC (super hard aluminum), and LD (forging aluminum). Casting aluminum alloys can be classified into four types based on the main alloying elements added: aluminum-silicon (Al-Si), aluminum-copper (Al-Cu), aluminum-magnesium (Al-Mg), and aluminum-zinc (Al-Zn) systems. Common grades include ADC12 (A383) and ADC10 (A380).
2. Advantages of Aluminum Alloy Die Casting: The quality of the product is good, with high dimensional accuracy of castings and good surface finish. The strength and hardness are relatively high. The strength is generally 25% to 30% higher than that of sand casting, but the elongation is reduced by about 70%. The dimensions are stable and interchangeable. Aluminum alloy die casting can produce thin-walled and complex castings. Currently, the minimum wall thickness of zinc alloy die casting can reach 0.3 mm, and that of aluminum alloy die casting can reach 0.5 mm. The production efficiency is high. For example, the domestic JⅢ3 type horizontal cold air die-casting aluminum machine can perform die-casting 600 to 700 times on average in eight hours, and a small hot-chamber die-casting aluminum machine can perform die-casting 3,000 to 7,000 times on average in eight hours. The economic effect is excellent. Due to the advantages of precise dimensions and smooth surface of die-casting aluminum parts, they are generally used directly without mechanical processing or with minimal processing. This improves metal utilization, reduces a large amount of processing equipment and labor, makes the price of castings cheaper, and allows the use of combination die-casting aluminum with other metals or non-metallic materials, saving assembly labor and metal.
3. Disadvantages of Aluminum Alloy Die Casting: Due to the high speed of liquid metal filling the cavity during die-casting, the flow state is unstable. Castings produced by general die-casting methods are prone to porosity and cannot be heat-treated. It is difficult to die-cast complex castings with internal concavities. The life of aluminum alloy die-casting molds is relatively low, with a lifespan of about 80,000 shots. It is not suitable for small-batch production because the manufacturing cost of die-casting molds is high, making small-batch production uneconomical. Aluminum alloy die-casting is not easy to achieve anodizing. Since die-casting often leaves many or sand holes, the appearance cannot be well repaired, and the oxidation process cannot cover the appearance issues.
Note: Pay special attention to the mold life of aluminum die-casting molds, the grades of die-casting aluminum, and the reasons why anodizing cannot be performed.
Aluminum Alloy Die Casting Process Production Workflow
Below is a die-casting process diagram.
Die-casting molds must be made of hot-working mold steel. Commonly used steels include H13, 8407, 2344, 8418, SKD61, DAC, FDAC, etc.
Below are images of the die-casting forming process.
After the product is formed, it needs subsequent processes such as sprue cutting, removal of flash and burrs, tapping, and heat reshaping to obtain a preliminary product that meets design requirements.
Note: Focus on how aluminum die-casting is carried out, what type of steel is used for aluminum molds, what the product looks like after production, and what post-processing is required.
Surface Pre-treatment of Aluminum Alloy Die Casting
1. Aluminum phosphating;
2. Physical polishing of aluminum surfaces;
3. Alkaline electrochemical polishing of aluminum (this is commonly used);
4. Environmentally friendly chemical polishing of aluminum and aluminum alloys;
5. Electrochemical surface strengthening treatment of aluminum and its alloys;
6. Electroplating treatment after polishing of aluminum alloys.
Note: To simplify the process, detailed explanations are omitted. For structural purposes, simply specify the desired product effect, and suppliers can select the polishing method based on the effect without requiring in-depth knowledge. To reduce costs, physical polishing is generally used. Those interested in further details can search online.
Surface Treatments for Aluminum Alloy Die Casting
1. Anodizing: Extruded aluminum alloy profiles have weak corrosion resistance and require anodizing to enhance their corrosion resistance, wear resistance, and aesthetic appearance.
2. Electrophoretic Coating: Electrophoretic-coated profiles have a soft gloss and can resist erosion from cement, mortar, and acid rain.
3. Powder Electrostatic Spraying: Powder electrostatic-sprayed profiles offer excellent corrosion resistance, with superior resistance to acids, alkalis, and salts compared to oxidized and colored profiles.
4. Titanium Plating and Gold Titanium Plating Processes: Titanium gold plating of aluminum profiles is a coating technology. It adds pre-plating and electroplating steps to conventional titanium plating processes. The pre-plating process involves chemically treating activated plated parts in a water solution of salt and hydrochloric acid to create colorful effects.
5. Wood Grain Transfer Printing: Vacuum wood grain film technology involves transferring wood grain patterns onto the surface of workpieces using heat transfer after electrostatic spraying of metal products. This process is fade-resistant and produces realistic wood grain patterns, enhancing product quality.
Note: Since aluminum generally uses electrolytic aluminum, surface treatment methods are largely similar to those in the previous two articles. However, the forming processes of these three methods result in different initial product surface effects, and the selected surface treatment effects also vary.
The most suitable surface treatments for aluminum alloy die-casting are electrophoretic painting and powder spraying or coating (commonly referred to as baking paint), as these can significantly reduce surface defect rates. For more detailed information, refer to historical records and search for "Understanding Aluminum II, Profiles" which provides an in-depth introduction to surface treatment processes.
Main Applications of Aluminum Alloys
1. Internal components of aerospace vehicles, aircraft, automobiles, trains, ships, etc.;
2. Appearance parts or internal components for the communications, electronics, and home appliance manufacturing industries.
Conclusion
1. When designing aluminum alloy die-casting parts, try to avoid斜顶structures to prevent difficulties in removing flash and burrs.
2. When designing aluminum alloy die-casting parts, ensure uniform wall thickness and smooth melt flow to reduce appearance defects caused by molding and minimize post-processing issues such as polishing and reinspection.
3. If a softer grade is selected, consider structural strength when designing load-bearing structures, as they may otherwise be prone to breakage.
