How to improve the corrosion resistance of precision die-casting products in Dalian by changing the die-casting process?

How to improve the corrosion resistance of precision die-casting products in Dalian by changing the die-casting process?

How to improve the corrosion resistance of precision die-casting products by changing the die-casting process in Dalian

1、 Optimize mold design

Improvement of flow channel system

Design a reasonable pouring system to ensure smooth and rapid filling of the metal liquid in the mold cavity. For example, using hot runner technology can make the temperature distribution of molten metal more uniform, avoiding defects such as cold insulation caused by local low temperatures. Cold insulation can cause discontinuity on the surface of die-casting products, which can easily form corrosion channels. Through the hot runner system, the molten metal can fill the mold cavity at an appropriate temperature, reduce internal stress of the product, improve product density, and enhance corrosion resistance.

Optimize the position and quantity of gates to make the flow path of molten metal in the mold cavity shorter and more uniform. This can prevent the metal liquid from generating vortices and entrainment during the flow process. Because the gas involved will form pores inside the die-casting product, these pores will make the protective film on the surface of the product incomplete and reduce its corrosion resistance. Reasonable gate design can effectively reduce the generation of pores and improve product quality.

Complete exhaust design

Precision die-casting molds require a good exhaust system. Install exhaust grooves or holes at the parting surface and joint of the insert block of the mold to ensure that the gas inside the mold cavity can be smoothly discharged. For example, the depth and width of the exhaust groove should be precisely designed according to the type of die-casting alloy and die-casting process parameters. If the exhaust is not smooth, the gas inside the mold cavity will be compressed under high pressure and merge into the molten metal, forming pores or loose structures after the product solidifies, which will accelerate the corrosion process.

2、 Control die-casting parameters

Die casting temperature regulation

Appropriately increase the pouring temperature of die-casting alloys. For common die-casting alloys such as aluminum alloys, appropriate pouring temperature can improve the fluidity of the alloy liquid, fill the mold cavity more fully, and reduce defects such as shrinkage and porosity. For example, the casting temperature of aluminum alloy is generally controlled between 620-680 ℃. Within this temperature range, the solidification process of the alloy is more uniform, which can form a denser structure and improve the corrosion resistance of the product.

At the same time, attention should also be paid to the control of mold temperature. Maintaining stable mold temperature helps to obtain uniformly quality die-casting products. Mold heating or cooling systems can be used to maintain the mold temperature within an appropriate range. When zinc alloy is die cast, the mold temperature is generally controlled at 180-220 ℃. The appropriate mold temperature can make the solidification speed of the alloy liquid in the mold cavity moderate, avoid defects caused by too fast or too slow solidification, and improve the corrosion resistance of the product.

Optimization of Pressure in Dalian Die Casting

Reasonable die-casting pressure can ensure that the metal liquid fills every corner of the mold cavity, reducing internal porosity and loose structure. For different die-casting alloys and product shapes, it is necessary to determine the appropriate die-casting pressure through experiments. For example, when die-casting products with complex thin-walled structures, high die-casting pressure is required to ensure that the metal liquid can smoothly fill the thin-walled part and prevent insufficient pouring. Insufficient watering can lead to incomplete surface of the product, which is prone to corrosion.

3、 Post processing technology

Surface treatment strengthening

After demolding of die-casting products, adopting appropriate surface treatment processes can significantly improve their corrosion resistance. For example, chemical plating is a commonly used method. By chemically plating nickel or chromium, a uniform and dense metal protective film can be formed on the surface of the product. The electroless nickel plating layer has good corrosion resistance and wear resistance, which can effectively prevent die-casting products from being corroded by external corrosive media.

Anodizing is also an effective surface treatment method, especially suitable for aluminum alloy die-casting products. Anodizing can generate an oxide film on the surface of the product, and by adjusting the oxidation process parameters, the thickness and properties of the oxide film can be controlled. A thick oxide film can better resist corrosion and can also meet the aesthetic requirements of the product through subsequent operations such as dyeing, while improving corrosion resistance.

Cleaning and passivation treatment

Dalian die-casting products need to be thoroughly cleaned after demolding to remove impurities such as release agents and oil stains on the surface. Efficient cleaning methods such as ultrasonic cleaning can be used to ensure the cleanliness of the product surface. Then passivation treatment is carried out, and the passivation solution can react chemically with the metal on the surface of the product to form a passivation film. This passivation film can serve to isolate metals from corrosive media and improve the corrosion resistance of the product. For example, for magnesium alloy die-casting products, using appropriate passivators for treatment can effectively prevent corrosion of magnesium alloys in humid environments.