Industrial rollers are one of the essential equipment in the manufacturing industry and are widely used in many industries such as printing, textiles, metal processing, papermaking and plastics. Their surface is usually plated with a layer of chrome to enhance wear resistance, corrosion resistance and hardness. However, under long-term high-intensity use, the chrome-plated surface may be damaged by wear, scratches or peeling, which not only affects the working efficiency of the equipment, but also may lead to a decline in product quality. Repairing the damaged chrome-plated surface of industrial rollers is a technically demanding job, and the correct methods and processes need to be adopted to ensure that the repaired surface is restored to its original performance level.

What are the common causes of chrome-plated surface damage?

Before discussing how to repair, we first need to understand the common causes of chrome-plated surface damage. This will help take corresponding measures during the repair process to prevent similar problems from happening again.

Mechanical wear

Mechanical wear is one of the most common causes of chrome-plated surface damage. Industrial rollers need to withstand huge pressure and friction during the production process. Long-term use will cause the chrome layer on the surface to gradually wear away and eventually expose the substrate. Wear will not only weaken the protective effect of the chrome layer, but may also cause more serious surface damage.

Scratches and collisions

During operation or transportation, industrial rollers may be scratched or collided by hard objects, resulting in obvious scratches or pits on the chrome-plated surface. These scratches not only affect the surface finish, but may also become stress concentration points, which will further expand in subsequent use and cause the chrome layer to fall off.

Chemical corrosion

Although the chrome-plated layer has strong corrosion resistance, the chrome-plated surface may still be corroded under certain special environments, such as working conditions with high pH or corrosive gases. This corrosion usually manifests itself as spots, cracks or holes on the surface, and in severe cases may even cause large areas of chrome layer to fall off.

Thermal stress

When industrial rollers are used in high-temperature environments, thermal stress may occur between the chrome-plated layer and the substrate due to different thermal expansion coefficients. If this stress exceeds the tolerance range of the chrome layer, cracks will appear on the surface, leading to the peeling of the chrome layer.

Insufficient adhesion of the chrome-plated layer

Sometimes, insufficient adhesion of the chrome-plated layer is also one of the causes of surface damage. This may be related to improper electroplating process, such as incomplete surface cleaning of the substrate and improper control of electroplating parameters. When the chrome layer has insufficient adhesion, the chrome-plated surface is prone to fall off or peel off due to external forces or environmental changes.

How to repair the damaged chrome-plated surface of industrial rollers?

Steps to repair the chrome-plated surface of industrial rollers:

1. Surface inspection and evaluation

2. Surface cleaning and removal of damaged layer

3. Surface repair and re-chrome plating

4. Surface polishing and passivation

5. Final inspection and quality control

Repairing the damaged chrome-plated surface of industrial rollers is a job that requires precision operation and usually includes the following steps:

Surface inspection and evaluation

Before starting the repair work, it is necessary to first conduct a comprehensive inspection and evaluation of the surface damage of the industrial roller. The inspection content includes the degree of wear, scratch depth, corrosion range and adhesion of the chrome layer. Through these inspections, the severity of the damage can be judged and the repair plan can be determined.

● Visual inspection: Use a high-power magnifying glass or microscope to visually inspect the roller surface to determine the distribution of scratches, cracks and wear areas.

● Measure thickness: Measure the thickness of the chrome-plated layer with a thickness measuring instrument to determine whether the degree of wear exceeds the repair range.

● Adhesion test: Use scratch test or other test methods to check the adhesion of the chrome plating layer and assess whether it has the risk of falling off.

Surface cleaning and removal of damaged layer

After confirming the scope of damage, the surface of the industrial roller needs to be cleaned and the damaged chrome plating layer removed. This step is very important because only by thoroughly removing the damaged layer can a good foundation be laid for subsequent repair work.

● Surface cleaning: Use chemical cleaners such as degreasers and pickling agents to clean the roller surface to remove surface oil, oxides and other impurities.

● Removal of damaged layer: Remove the damaged chrome plating layer by mechanical grinding or chemical dissolution. Mechanical grinding is usually performed using fine sandpaper or grinding wheels, while chemical dissolution requires the use of special dissolving liquids to remove the chrome layer.

Surface repair and re-chrome plating

After removing the damaged layer, the roller surface needs to be repaired and re-chrome plated. This is the core step of the entire repair process and is directly related to the effect after the repair.

● Substrate repair: If the surface of the substrate is exposed and damaged due to the chromium layer falling off, the substrate needs to be repaired, such as filling pits or cracks with welding, filling materials, etc., to ensure that the surface of the substrate is flat and smooth.

● Re-chrome plating: The surface of the repaired roller needs to be re-chrome plated. The process of re-chrome plating is similar to that of the initial chrome plating, including surface treatment, electroplating and post-treatment. During the electroplating process, the current density, temperature and time must be strictly controlled to ensure that the chrome plating layer is uniform and firmly attached.

Surface polishing and passivation

After the re-chrome plating is completed, the surface usually needs to be polished to improve its finish and wear resistance. At the same time, proper passivation treatment can also enhance the corrosion resistance of the chrome layer.

● Surface polishing: Use a polishing machine to finely polish the roller surface to remove minor defects that may occur during the electroplating process so that the surface achieves a mirror effect.

● Passivation treatment: Passivation treatment can be carried out by chemical or electrochemical methods to form a dense oxide film on the surface of the chromium layer, further improving its corrosion resistance.

Final inspection and quality control

After the repair work is completed, the chrome-plated surface of the industrial roller must be subjected to final inspection and quality control. This step ensures that the repaired roller surface meets the use requirements and can be put into normal production.

● Surface inspection: Visual inspection and thickness measurement are performed again to ensure that the uniformity and thickness of the chrome-plated layer meet the standards.

● Adhesion test: Adhesion test the repaired chrome-plated layer to confirm that it can withstand the stress and friction under normal working conditions.

● Functional test: According to the actual use of the industrial roller, a functional test simulating working conditions can be performed to ensure that the wear resistance, corrosion resistance and hardness of the roller surface meet the expected effect.

What are the precautions for repairing the chrome-plated surface?

When repairing the damaged chrome-plated surface of the industrial roller, the following points must be noted to ensure the repair effect and the service life of the roller.

Ensure the integrity of the substrate

When repairing the chrome-plated surface, the integrity of the substrate is crucial. If the substrate is severely damaged or has hidden defects, even if the chrome is re-plated, the adhesion of the chrome layer may be insufficient, resulting in unsatisfactory repair results. Therefore, the substrate must be fully inspected and repaired before repair.

Control electroplating process parameters

The control of electroplating process parameters has a direct impact on the quality of the repaired chrome layer. Especially in the re-chrome plating process, the current density, temperature, time and electrolyte composition need to be strictly controlled to ensure the thickness and uniformity of the chrome layer.

Avoid over-polishing

Although surface polishing can improve the finish, over-polishing may weaken the thickness of the chrome layer and even cause the chrome layer to be too thin locally. Therefore, during the polishing process, appropriate polishing processes and tools should be selected according to specific requirements to avoid secondary damage to the chrome layer.

Choose appropriate passivation treatment

Passivation treatment is an important means to improve the corrosion resistance of the chrome layer. When selecting a passivating agent, the most suitable chemical composition and process parameters should be selected according to the working environment and use requirements of the roller to achieve the best passivation effect.

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