Chromium-plated rollers refer to steel rollers coated with a layer of hard chromium. The required thickness of the chromium plating ranges from 2 to 10 mils, or 20 to 100 micrometres, depending on the specific application requirements. After chromium plating, the surface takes on a bright white appearance; upon closer inspection, it exhibits a slight granular texture and a faint bluish tint. The hardness of chrome-plated rollers exceeds that of other steel tubes and round bars after high-frequency hardening, as well as that of alloy steel following heat treatment. In practical processing and testing, the hardness of Ruitong products ranges from 50° to 90° on the Rockwell scale, depending on the processing thickness.
After chrome plating, the hardness of the steel roll body is significantly increased. As the surface finish improves, the coefficient of friction decreases, thereby greatly extending the product’s service life. The chrome-plated layer also offers resistance to acids and alkalis, as well as corrosion resistance, ensuring stability in various environments and minimising the likelihood of chemical reactions. Should the chromium plating on the surface become damaged, the roll can simply be re-plated and reused, significantly reducing the time and cost associated with remanufacturing.
Chromium-plated rolls are suitable for various film production lines, paper production lines, large-scale printing equipment and coating equipment. They are widely used in flexographic printing presses, water-based ink printing presses and coating machines, and can also be used for pressing plastics, leather and paper.
In most cases, a chrome-plated roller is a machined and polished steel roller with a hard chrome coating. In most instances, the applied coating is bright white. If you look closely, you will notice a slight bluish tint; the chrome-plated roller must have a coating of at least two micrometres or 20 micrometres in thickness. Otherwise, the hard chrome plating process will be ineffective. The main functions and advantages of chrome-plated rollers are as follows:
1. The primary advantage of chrome-plated rollers is their high hardness. Compared to standard metal steel tubes and round bars of the same grade—such as alloy steel—their hardness after heat treatment is superior, particularly when considering practical production and operational environments. This outperforms hardening processes such as carbon diffusion, nitrogen diffusion and high-frequency hardening. In practical measurements, the hardness of chrome-plated rollers typically ranges between 55 and 65 on the Rockwell scale.
2. High wear resistance and low coefficient of friction. As the hardness of chrome-plated steel rollers is significantly increased, the coefficient of friction is correspondingly reduced, thereby extending the service life of the rollers.
3. As the chrome coating on chrome-plated rollers is highly stable under various conditions, it is resistant to chemical reactions and is not corroded by certain acidic or alkaline liquids and gases.
4. Should the chrome plating on the surface of a chrome-plated roller become damaged, it can be re-plated, thereby reducing operating costs and allowing for repeated use.
Owing to the aforementioned advantages of chrome-plated rollers, they have found widespread application. Most mechanical equipment production lines utilise them for the manufacture of mirror rollers and super-mirror rollers. Industrial upgrading represents the future trend in an environmentally friendly context.
