What are the corroded forms of injection molds, and how to maintain them?
by：Vowin Rapid Prototyping2023-02-07
After many injection molds are developed, due to customer demand and market conditions, production will stop for a period of time after completion, which means that a large part of the time after the mold is manufactured is idle. At this time, special attention should be paid to the maintenance of the mold , There must be no corrosion. Once corrosion occurs, it will definitely affect the subsequent use of the mold. So what are the forms of mold corrosion and how to maintain the mold well? Let's take a look together.
There are various forms of corrosion failure of mold steel materials in industrial production. Under the action of different steel materials under different loads and different medium environments, the corrosion forms of mold steel mainly include the following types:
① General corrosion
A large area of relatively uniform corrosion occurs on the exposed surface of the steel material. Although the effective area of the component under force and its service life are reduced, it is less harmful than localized corrosion.
② Intergranular corrosion
Refers to the corrosion along the product boundary, which destroys the connection of the grains. This kind of corrosion is the most harmful. It may make the gold brittle or lose its strength, lose the metal sound when knocked, and easily cause sudden accidents. Product corrosion is the main corrosion form of austenitic stainless steel. This is due to the difference in the composition or stress between the product boundary area and the intragranular, which causes the electrode potential in the product boundary area to significantly decrease and cause the difference in electrode potential.
③ Stress corrosion
The metal cracks under the joint action of corrosive medium and tensile stress (external stress or internal stress). The fracture mode is mainly intergranular and also transgranular. This is a dangerous low-stress brittle fracture. Stress corrosion often occurs in chlorination and alkaline atmosphere oxides or other water-soluble media. It accounts for many equipment accidents. Quite a large proportion.
④ pitting corrosion
Pitting corrosion is a form of corrosion damage that occurs in a local area of the metal surface. After the formation of pitting corrosion, it can develop rapidly to the depth and finally penetrate the metal. Pitting corrosion is very harmful, especially for various containers. After pitting corrosion occurs, it should be polished or painted in time to avoid corrosion deepening.
The cause of pitting corrosion is that the passivation film on the metal surface is partially damaged under the action of the medium. Or in a medium containing chloride ions, loose surface defects and non-metallic inclusions can cause pitting corrosion.
⑤ Corrosion fatigue
The destruction of metal under the action of corrosive medium and alternating stress is characterized by corrosion pits and a large number of cracks. Significantly reduces the fatigue strength of steel, leading to premature fracture. Corrosion fatigue is different from mechanical fatigue. It has no certain fatigue limit. As the number of cycles increases, the fatigue strength always decreases.
How to prevent the mold from being corroded
1. Avoid placing the mold in a humid environment
As the ancients said, water drips through stone. The same is true for the mold. If it is placed in a humid place for a long time, it is useless to use the best anti-rust agent, and it will eventually cause the mold to rust. Therefore, when we remove the mold from the machine, we must pay attention to the storage environment. It is best to choose to place it on a dry and ventilated mold rack.
2. Avoid direct contact with the mold with hands
Workers' hands will sweat, and it is easy to get the sweat on the workpiece. It can be prevented by wearing gloves.
3. The anti-rust agent can only be used after the mold cools down
If the anti-rust agent is sprayed before the mold cools down, the mold will rust within a few days. The reason is that before the mold returns to temperature, it will absorb the moisture in the anti-rust agent and produce signs of rust. The best way is to wait for the mold to cool down naturally, and then use the mold antirust agent after cooling down.
4. According to the anti-rust requirements, long-term anti-rust agents should be selected
At present, there are many antirust agents, antirust oils and antirust powders on the market. However, the long-term anti-rust agent is a professional mold anti-rust agent, and the general anti-rust cycle is 1 to 3 years. It can effectively guarantee the mold safety of the factory and reduce unnecessary losses.