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Measures to prevent contamination of precision castings

Measures to prevent contamination of precision castings

Precision castings contain a variety of metallic and non-metallic impurities, resulting in loose structure and high porosity, so it is often difficult to ensure the quality of the oxide film. According to the manufacturer's years of experience, the following methods can be adopted to avoid this problem.

1. The surface polishing method is to grind the polished aluminum, fill the gaps left by the oxidized part, and connect the resulting gaps together, acting as a bridge.

2. High voltage and high current density impact method. That is, in the early stage of oxidation of precision castings, high-voltage electric shocks are used to connect the oxidized parts to pieces through electric shocks.

3. The surface shot peening method is to use a round head hammer to hit the gap and close it by hitting to achieve the purpose of connecting into pieces.

Therefore, when using precision castings, if the anodic oxide film is dyed, white spots may appear. The above methods can help you. Which method is used to avoid actual problems depends on the pollution degree of the casting.

Feature appearances that may appear on the surface of precision castings

In the production process of precision castings, in addition to the layers of processing, the most critical step is injection molding, that is, molding into the shape of the factory in the mold. However, sometimes the surface of precision castings will show scratch marks along the ejection direction, that is, scratches. Generally, it has two characteristics.

One is that when the quality of the mold forming surface is poor, the precision castings are demolded, causing strains. Most of the channels are straight (in the demolding direction), the shallow is less than 0.1 mm, and the deep is about 0.3 mm. When the scratches are severe, mold sticking occurs, and stainless steel castings cannot even come out. The abrasion phenomenon is most serious in aluminum alloy.

The second feature is that after the metal stream hits the profile wall, it causes strong welding or adhesion of the metal to the profile wall (like the adhesion phenomenon of throwing thick paste-like mud on the wall with force, the greater the force, the adhesion The more), and when the adhesion part is demoulding, the metal is squeezed and the skin layer is torn, and the precision casting part is strained.