Causes of Rust in Mold and Solutions

Causes of Rust in Mold and Solutions

Injection molding molds are mostly made of tool steel. During work, it will encounter corrosive gases, water and other substances that cause rust. The plastic parts made from rusty molds will have quality problems which must be eliminated. 

We will analyze the reasons and its elimination methods from three aspects in the following:

1. The gas generated by the decomposition of the melt plastic

The gas will be generated after the plastic resin is heated. Many raw materials also produce volatile gas if overheated as well. These gases are corrosive and are diffused around the machine. When the mold is not working, they will corrode the mold. Therefore, when the machine stops working, use a soft cloth to clean the mold and close it.

If it is not used for a long time, the mold cavity should be sprayed with anti-rust agent, and grease should be applied when closing the mold and the gate should be blocked.

2. Cooling water in the mold

Cooling water is often used in the mold for cooling, so there is more moisture around the machine. 

If the mold is cooled below the dew point, the moisture in the air will form water droplets on the surface of the mold. If it is not wiped off in time, it will be easy to rust. Especially after the mold is working, condensed water will be generated very soon. Therefore, when stop the molding turn off the cooling water and wipe the mold dry.

3. Carbon atoms produced during molding

After the mold works for a long time, carbides are precipitated and decomposed in the molding material. This often causes the mold to wear, corrode or rust. Thus, if we find the carbide is formed, we should wipe it off and clean with a dry cloth immediately.

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