In order to make the rubber and metal adhere better, in the rubber manufacturing, the metal skeleton needs to be chemically treated. The common treatment methods are as follows:

1） acid etching

The method comprises immersing the metal skeleton in a certain concentration and a certain kind of acid solution for a certain period of time, and then performing rinsing and drying. In general, the acid treatment of steel parts is to first clean the metal skeleton with solvent gasoline to remove oil stains. Then, the skeleton was immersed in 1:1 diluted hydrochloric acid for 10 min, and immediately washed out with a large amount of cold water, then dried and set aside.

This method is mostly applicable to small skeletons of iron and steel. Alternatively, the surface of the metal part may be degreased first, then washed with hot water, treated with 30% hydrochloric acid to remove oxides, then washed with water and subjected to a second acid treatment, and immersed in 0.5% sulfuric acid for 2-3 s. After the boiling water is rinsed, it is not used, but the parking time should not be too long, otherwise it will be re-treated. A new phosphating process can also be used to impart chemical inertness to the metal surface, improve the surface corrosion resistance, high temperature resistance, moisture resistance, and form a certain metal surface structure, thereby improving the bonding strength between the metal and the rubber product. Further washing with chromite will provide better surface inertness. Easy to save for a longer time. The treatment agents used in the above processes have been standardized and can be purchased from the market, and the process can be organized to form a production process line.

2） alkali treatment

Solvent oil should be used to remove oil stains before treatment, then placed in 5%-10% sodium hydroxide solution, soaked 5-10mm at 60 °C, rinsed with water, then dried and ready for use. This method is mostly applicable to the skeleton treatment of copper and copper alloys.

3） anodizing method

Phosphoric acid, sulfuric acid and chromic acid are usually used for anodization to treat the surface of the metal skeleton to meet the requirements for use.

4） phosphating

5 Phosphating treatment is mainly to cause phosphating reaction on the surface of metal (such as steel and iron) skeleton to form phosphating layer and improve the bonding strength between rubber grommets and hardware.