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Tips for Rust Removal and Paint Treatment of Steel Molds

Jul. 19, 2023

As we all know, the processing material of steel mold plate is steel plate, steel plate is directly exposed to the air or long-term immersion in water, especially seawater, very easy to rust and corrosion. In order to extend the service life, so when the steel mold plate processing is completed, it must be brushed with paint for protection, and must pay attention to some operational details before painting, only grasp these details, can effectively do a good job of protection.

I. Drying

If the steel plate is soaked in water or rained, the water on the surface is not completely evaporated before painting, it will make the paint and steel plate layered with isolation, the paint can't be tightly attached to the steel plate, and the paint is easy to fall off. Therefore, it is especially important to keep the steel mold dry.

Ⅱ. No oil

In addition to remove the oil on the surface of the steel molds, shaped molds due to the limitations of the edges and corners, the grinder can not reach. Degreasing can use the corresponding commodity degreasing agent, can also use etergent with strong detergency. Cleanup tools can choose hard floor brush which divided into small floor brush and horizontal floor brush.

Ⅲ. No rust

Clean the floating rust, welding slag, or other paint on the surface of the steel formwork, but be careful not to treat the surface too smooth, as it will endanger the turnover frequency of the formwork paint. The rust removal methods include manual rust removal, mechanical rust removal, and chemical rust removal.

(1) Manual rust removal

Tools for manual rust removal include hammers, shovels, scrapers, wire brushes, etc. Generally, thick rust spots are loosened with hammers and then removed with shovels. The labor intensity is high, the rust removal efficiency is low, usually 0.2-0.5m2/h, and the environment is harsh, making it difficult to remove dirt such as oxide skin. The rust removal effect is poor, and it is difficult to achieve the specified cleanliness and roughness. It has gradually been replaced by mechanical and chemical methods. But in the repair of local defects, this method is often used; For areas that are difficult to achieve by mechanical rust removal, such as narrow areas, corners and edges on the opposite side of the section steel, manual rust removal is also commonly used.

(2) There are many tools and processes for mechanical rust removal, including the following:

①Small pneumatic or electric rust removal. Mainly powered by electricity or compressed air, equipped with appropriate rust removal devices for reciprocating or rotary motion to meet the rust removal requirements of various occasions. Such as angle grinder, wire brush, pneumatic needle beam rust remover, pneumatic rust hammer, toothed rotary rust remover, etc., belong to semi mechanized equipment. The tools are lightweight and highly mobile, and can thoroughly remove rust and old coatings. They can perform roughening treatment on coatings, greatly improving efficiency compared to manual rust removal, up to 1-2 m2/h. However, they cannot remove oxide skin, have small surface roughness, and cannot achieve high-quality surface treatment quality, The work efficiency is lower than that of spray treatment. It can be used in any part, especially in the process of ship repair and is widely used.

②Shot blasting (sand) for rust removal. Mainly composed of particle jet erosion to achieve surface cleanliness and suitable roughness, equipment includes open shot (sand) rust removal machine, closed shot (sand chamber), and vacuum shot (sand) machine. The open type shot blasting (sand) machine is widely used and can thoroughly remove all impurities on the metal surface, such as oxide skin, rust, and old paint film. The rust removal efficiency is high by 4-5m2/h, with high mechanical degree and good rust removal quality. However, due to the fact that abrasive materials cannot be recycled and have an impact on other operations, cleaning the site is troublesome. So environmental pollution is severe and has been gradually restricted in recent times.

③High pressure water abrasive rust removal. Utilize the impact of high-pressure water jet (combined with abrasive grinding) and water prying to destroy the adhesion of rust and coating to the steel plate. Its characteristic is no dust pollution, does not damage the steel plate, greatly improves the rust removal efficiency, can reach over 15m2/h, and has good rust removal quality. However, the steel plate after rust removal is prone to rusting, and special wet rust removal coatings must be applied, which has a significant impact on the coating of general performance coatings.

④Shot blasting for rust removal. Shot blasting is an advanced mechanical treatment method that uses high-speed rotating impellers to remove rust from the steel surface. It not only has high production efficiency, but also low cost and high degree of automation. It can achieve assembly line operation with less environmental pollution, but is only operated indoors.

After rust removal is completed, the final cleaning of the steel formwork should be carried out before painting. Some floating ash on the surface should be cleaned, wiped clean with a dry sponge or cloth, and dried. Workers need to wear foot covers when painting to prevent further contamination of the steel formwork. When painting, try to arrange it in high temperatures, where the paint is more easily diluted and diffused, and the adhesion with the steel plate is stronger.

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Ningbo Tianyuan Construction Engineering Co., Ltd.
Ningbo Tianyuan Cement Products Co., Ltd.