Analysis of Vacuum Die Casting Technology
Tue Jul 04 08:33:42 CST 2023
Defects of ordinary die casting process
Conventional high pressure casting
(Standard die-casting mold exhaust with slag bag and exhaust groove)
1. Since the material liquid at the ingate is sprayed at high speed, 40%~90% of the material liquid will be in contact with the gas in the cavity and the outside air.
2. During high-speed filling, the more gas involved in the material liquid, the higher the porosity of the casting, and it is difficult to meet the air tightness and mechanical performance requirements of seals, structural parts and other products.
Vacuum Die Casting
1. Eliminate or reduce the pores inside the product, improve the mechanical properties and surface quality of die castings;
2. The back pressure of the cavity is greatly reduced, and the liquid flow speed is accelerated to improve the filling conditions;
3. With the increasing number of structural parts, the control of pore defects is becoming more and more strict, and the vacuum degree in the cavity is higher when the forming mold is filled. The concept of high pressure casting - high vacuum die casting is also gradually becoming Standards accepted and considered by die casting companies.
Advantages of Vacuum Die Casting Production
1. Before high-speed filling, 80-90% of the gas in the cavity has been discharged. During the high-speed filling process, the probability of entrained air is low, and the risk of casting pores is small;
2. Negative pressure is formed in the cavity, which has adsorption force on the molten metal and can increase the fluidity of the molten metal. The effect is most obvious on materials with poor fluidity such as pure aluminum and high thermal conductivity aluminum;
3. The filling pressure of vacuum die casting is 30%~50% lower than that of ordinary die casting, which greatly improves the life of the mold;
4. The mass ratio of the die-casting gating system (runner, slag ladle) is lower, and the recycled material is reduced by more than 20%, which effectively reduces the
Die casting cost.
The advantages of vacuum die casting
1. Can be welded;
2. The internal structure of the casting is dense and the air tightness is good;
3. The porosity is low, and there will be basically no porosity exposed after post-processing;
4. After surface treatment (anodizing, electroplating, powder spraying, etc.), the risk of defects such as surface blistering is low;
5. T6 heat treatment can be carried out to obtain mechanical properties such as higher tensile strength, yield strength and good elongation.
Applicable process range of vacuum
1. Die-casting of zinc, aluminum, magnesium and copper.
2. Semi-solid die casting, low pressure casting.
3. Liquid die forging, squeeze casting.
4. Plastic, resin molding, etc.
Scope of application of vacuum die casting
1. High-strength structural parts
2. Airtight parts
3. Auto parts
4. Communication filter
5. Pure aluminum/anodized aluminum parts
6. Plating parts
7. Electric tools
8. Other high-quality die-casting parts.
Comparison of traditional die-casting, ultra-low speed die-casting and vacuum die-casting
1. Traditional die-casting. There are many pores during molding, and the limitations of making high-demand products are large;
2. Ultra-low speed die-casting. There are fewer air holes when forming, but it has great limitations on product structure;
3. Vacuum die-casting. There are fewer air holes when forming, but it has little limitation on product structure;
4. Ultra-low-speed vacuum die-casting. On the basis of ultra-low-speed die-casting and vacuum die-casting, the product quality has been improved again, and products with higher requirements and higher quality can be made.