Why the injection mold is rusted? How to prevent?

  • March 14, 2018
  • Categories: Blog

The materials of plastic injection molds are not resistant to rust commonly. They may rust if they are exposed to water or corrosive gases. The quality of plastic parts produced by this kind of rusted mold will be greatly affected. Therefore, rust should be avoided as far as possible.

1. Overheating of the molten material produces gas that leads to rust and its prevention.
When the temperature of molten material is too high in the canister, many raw materials will produce volatile gas due to overheating. This gas is very corrosive and will corrode molds and machines. In order to make the mold less suffer or avoid the corrosion of the volatile gas, first of all control the canister temperature and make it do not overheat; Next, must use a clean soft cloth to clean the mold when stopping injection molding; Third, when the mold is not used for a long time, anti-rust agent should be sprayed in the mold cavity. When closing the mold, also coat it with butter is and plug the gate.

2. Slag carbides cause rust and its prevention.
After the mold has been working for a long time, the precipitated or decomposed carbides from the molten material will stick to the mold cavity. They have greater hardness and corrosion, and often make mold corrosion or wear. In order to avoid corrosion and rust, once carbide is found, it should be immediately wiped off with a dry cloth. If it is hard to wipe off, moisten it with a little alcohol and it can be wiped.

3. Cooling water indirectly causes rust and its prevention.
Cooling water is to be passed through the mold. If the cooling water cools the mold below the dew point, the moisture in the air will condense into water droplets on the mold surface, which will easily cause the mold to rust. Although the molten material temperature in the molding process will not drop below the dew point due to the high temperature, but once the molding stops, it is easy to form cooling water. Therefore, in the production process, it is best not to stop the molding operation, if it needs to stop, the cooling water should be shut off in time. If water droplets are found on the mold, dry it immediately.

4. Electroplated coatings defects lead to rust and its prevention.
The Electroplated coating in the cavity is very dense and of strong rust resistance. But if the plating process conditions are not controlled well, the Electroplated coating is loose, and the organization is not very tight. At this time, the volatile corrosion gas in cavity will be through these weak spots into the plating bottom, causing coating corrosion. To this end, the coating needs to be retreated, or coated with heat-resistant adhesives to fill loose areas, or replated.

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