1. Does zinc alloy die casting need surface treatment?
1.1, do surface treatment scene
The chemical properties of zinc alloy material are unstable, so it is easy to be oxidized, blackened, or yellowed in the air. If the zinc alloy die casting is exposed to the outside and oxidized, it will affect the appearance of the product.
Generally, the products are used outside, so they need to do surface treatment, including electroplating, baking paint treatment, powder spraying and other processes.
1.2, no surface treatment scene
If the zinc alloy die-casting parts are used for mechanical parts, there is no special requirement in performance, so surface treatment and electroplating are not necessary.
2. Use of zinc alloy
Zinc alloy is suitable for die-casting instruments, toys, lamps, decorations, electrical components and their boxes, auto parts, electromechanical parts, mechanical parts, etc.
3. What are the advantages and disadvantages of zinc alloys
3.1 Advantages of zinc alloy
1. Relatively large.
2. Good casting performance, can die-cast precision parts with complex shapes and thin walls, and the surface of the castings is smooth.
3. Surface treatment: electroplating, spraying, painting, polishing, grinding, etc.
4. When melting and die-casting, it does not absorb iron, does not corrode the pressure, and does not stick to the mold.
5. It has good mechanical properties and wear resistance at room temperature.
6. Low melting point, melting at 385℃, easy to die-casting.
3.2 Disadvantages of zinc alloy
It has a low melting point, but it melts at 385°C and is easy to be die-casted; while melting and die-casting, it does not absorb iron, corrode the profiling, and does not stick to the mold. Secondly, the creep strength is not high, spontaneous combustion and dimensional changes are prone to occur. In addition, according to the processing technology, it can be divided into two categories: cast zinc alloy and wrought zinc alloy.
4. Polishing process
Zinc alloy polishing process:
1. For products with medium requirements, manually pass the grinding line first.
2. Put a rough grindstone to grind off the surface sand line first, the grinding time depends on the product.
3. After polishing with the polishing stone, it can be directly electroplated after being removed. The electroplating is more beautiful than the artificial electroplating through the cloth wheel.
Processing:
1. Manually pass the clamping line, and if the requirements are very high, the entire product surface must be sanded.
2. Directly add polishing stone and special abrasive for zinc alloy. Grinding time depends on the product
3. Rinse directly, add polishing agent and polish for 10-20 minutes, then take it out and electroplating directly.
5. The difference between zinc alloy and aluminum alloy
Zinc alloy has a low melting point and can be melted at about 400 degrees. It has good castability and is easy to die-casting. It can easily produce a variety of styles and shapes without a lot of machining procedures. It has low casting cost and is easy to electroplating. The effect after electroplating is good. .
Aluminum alloys are widely used in aerospace, automobile, machinery manufacturing, shipbuilding and other industries. Its melting point is about 700 degrees and the process cost is higher than that of zinc alloys.
The difference in the melting point temperature of the two also restricts the use of the product. Zinc alloys cannot be used at too high temperatures or at too low temperatures (below 0°C). Zinc alloys can only be used at room temperature. Mechanical behavior.
In addition, the wear resistance and corrosion resistance of zinc alloys are not as good as aluminum alloys. Zinc alloys usually fade after being used for a period of time, and are prone to ageing, swelling and deformation, and even brittle and cracking.
The performance of aluminum alloy is relatively stable, and the anodizing process can ensure that it will not be corroded or faded for at least 10 years.
This is also the reason why our doors and windows all use aluminum alloy instead of zinc alloy.
Of course, apart from being more plastic than aluminum alloy, zinc alloy has higher hardness and tensile strength than aluminum alloy (zinc alloy hardness 60~140, tensile strength 260~440; aluminum alloy hardness 45~90, tensile strength 120~290 ).