Laminar flow rollers play a key role in the strip cooling and transport process in steel plants. When the strip passes through the laminar cooling area during continuous production, the laminar flow rollers are responsible for supporting and guiding the strip to run smoothly. Laminar flow cooling usually uses a large amount of cooling water to evenly spray on the surface of the strip in a laminar flow state to achieve rapid cooling.
On the one hand, the laminar flow roller must bear the weight of the strip to ensure that the strip maintains a stable position during the cooling process; on the other hand, its surface finish and flatness have an important impact on the surface quality of the strip. The friction between the strip and the laminar flow roller should be as small as possible to prevent the strip surface from being scratched. At the same time, the laminar flow rollers are arranged in such a way that the strip can evenly contact the cooling water to ensure the consistency of the cooling effect.

Why Laminar Flow Rollers Need Frequent Maintenance?
1. Poor working environment
- Contact with corrosive media: In many industrial production processes, laminar flow rollers will come into contact with various corrosive liquids or gases. For example, in the pickling process of metal processing, laminar flow rollers will be exposed to acidic solutions, such as hydrochloric acid, sulfuric acid, etc. These corrosive media will chemically react with the surface of the laminar flow roller, causing surface materials to be corroded and causing damage such as pits and plaques. After being exposed to such an environment for a long time, the service life of the laminar flow roller will be greatly shortened, requiring frequent maintenance to restore its surface performance.
- Withstand high temperature effects: Some laminar flow rollers work in high temperature environments, such as laminar flow cooling rollers in steel hot rolling production lines. During the hot rolling process, the strip temperature is very high, and the laminar cooling roller itself will absorb a lot of heat while cooling the strip. High temperature will change the properties of laminar flow roller materials, such as reducing the strength and hardness of the material. Moreover, high temperature may also cause thermal expansion of the laminar flow roller, causing its size to change and affecting the matching accuracy with other components. Repeated thermal cycles can also produce thermal stress, which can cause cracks and other damage to the surface of the laminar flow roller, requiring periodic maintenance.
- Withstand high friction: During the working process, there is continuous friction between the laminar flow roller and the materials being processed (such as paper, metal sheets, plastic films, etc.). Taking the papermaking industry as an example, paper passes at high speed on the surface of the laminar flow roller, and friction will cause the surface of the laminar flow roller to wear, resulting in an increase in surface roughness. As the wear increases, it will not only affect the quality of the paper (such as causing the paper surface to be uneven), but also further accelerate the damage of the laminar flow roller, so frequent maintenance is required to restore its surface accuracy.
2. High work intensity
- Long-term continuous operation: In many automated production lines, laminar flow rollers need to work continuously for a long time. For example, laminar flow rollers used in conveyor belts on automobile production lines may need to work continuously for several hours or even ten hours a day. Long-term operation makes the components of the laminar flow roller prone to fatigue wear. Just like a metal rod that is bent frequently will eventually break at the bend, certain key parts of the laminar flow roller (such as the bearing fit, the edge where the roller surface contacts the material) will gradually fatigue under long-term stress. Cracks, which in turn lead to component damage, require frequent repairs to replace damaged components or repair worn surfaces.
- High load operation: Laminar flow rollers need to withstand large loads in some industrial applications. For example, in the hot-rolled strip production line of a large steel plant, laminar cooling rollers need to support and transport thick steel strips, and huge pressure acts on the laminar flow rollers. This high load will cause large deformation and stress concentration in the laminar flow roller, which can easily cause damage such as bending and denting of the roller body. Moreover, high load will also increase the friction between the laminar flow roller and the steel belt and accelerate wear, so frequent maintenance is required to ensure its normal operation.
3. High accuracy requirements
- Great impact on product quality: The accuracy of the laminar flow roller (such as dimensional accuracy, surface roughness, cylindricity, etc.) directly affects the quality of the product. Taking plastic film production as an example, the surface accuracy of the laminar flow roller will determine the thickness uniformity and surface smoothness of the film. If the surface of the laminar flow roller is worn or deformed, the quality of the film will decrease, and problems such as uneven thickness and scratches on the surface will occur. In order to ensure product quality, once the accuracy of the laminar flow roller drops slightly, it needs to be repaired in time to restore its high-precision working condition.
- High precision with other parts: Laminar flow rollers usually need to work with other parts (such as motors, transmission belts, bearings, etc.) accurately to work properly. For example, in printing machinery, the rotational speed of the laminar flow roller needs to accurately match the rotational speed of the printing plate roller to ensure printing clarity and color uniformity. If the size of the laminar flow roller changes or the surface is damaged, it will affect the matching accuracy with other components, requiring maintenance to adjust or repair to ensure the normal operation of the entire equipment system.

Laser Cladding Repair Laminar Flow Roller Process
The process of laser cladding repair of laminar flow roller is as follows:
- Conduct a comprehensive inspection of the laminar flow roller to be repaired to determine its wear, corrosion, etc., and evaluate whether it is suitable for laser cladding repair.
- Clean the surface of the laminar flow roller to remove oil stains, rust and other impurities to ensure good combination between the cladding layer and the substrate.
- According to the material and use requirements of the laminar flow roller, select appropriate laser cladding materials, such as iron-based, nickel-based, cobalt-based alloy powders.
- Install the laminar flow roller on the laser cladding equipment, and adjust the parameters of the laser beam, such as power, scanning speed, spot size, etc.
- The selected laser cladding material is evenly coated on the surface of the laminar flow roller, and then heated with a laser beam to melt and form a metallurgical bond with the substrate.
- During the laser cladding process, the scanning speed and overlap rate of the laser beam need to be controlled to ensure the quality and uniformity of the cladding layer.
- Carry out appropriate heat treatment, such as annealing, quenching, etc., on the clad laminar flow roller to improve the structure and performance of the cladding layer.
- Perform surface processing on the repaired laminar flow roller, such as grinding, polishing, etc., to make its surface finish meet the requirements.
- Conduct a comprehensive inspection on the repaired laminar flow roller, including non-destructive testing, hardness testing, etc., to ensure that its quality and performance meet the requirements.
- Pack and label qualified laminar flow rollers for storage and transportation.
Advantages Of Laser Cladding Repair Laminar Flow Rollers
The advantages of laser cladding repair of laminar flow rolls are as follows
1. Good repair results
- High bonding strength: Laser cladding can form a good metallurgical bond between the cladding material and the laminar flow roller matrix. The bonding strength is much higher than traditional repair methods such as welding or spray welding. The repaired laminar flow roller is less likely to appear during use. The problem of spalling of the cladding layer ensures the reliability and durability of the repaired part.
- Excellent structural properties: The rapid heating and cooling rates during the laser cladding process make the structure of the cladding layer fine and dense, with high hardness, wear resistance and corrosion resistance. This can significantly improve the surface properties of the laminar flow roller and extend its service life.
2. Precise repair control
- Precise positioning: The energy and position of the laser beam can be precisely controlled, and can accurately repair defects such as local wear and scratches on the surface of the laminar flow roller, avoiding unnecessary processing of undamaged parts, reducing material waste and damage to the matrix thermal impact.
- Strong customizability: According to the specific usage requirements and working conditions of the laminar flow roller, appropriate cladding materials and process parameters can be selected to customize the performance of the repair layer to meet different repair needs
3. Efficient repair process
- Fast repair speed: The energy of laser cladding is concentrated, the heating speed is fast, and the cladding process is short. It can complete the repair of laminar flow rollers in a short time, improve production efficiency, and reduce equipment downtime.
- High degree of automation: Laser cladding equipment can be combined with automated control systems to realize automated operations in the repair process, reducing the difficulty and labor intensity of manual operations and improving the quality and stability of repairs.
4. Environmentally friendly
There is no open flame, no smoke, and no noise during the laser cladding process, causing little environmental pollution and complying with the environmental protection requirements of modern industrial production.
Disadvantages Of Laser Cladding Repair Laminar Flow Rollers
- High equipment cost: Laser cladding equipment is expensive and the investment cost is high, which may be a large burden for some small businesses or maintenance units. In addition, the maintenance and upkeep costs of the equipment are also high, requiring professional technicians to operate and maintain them.
- High technical requirements: Laser cladding technology is an advanced surface repair technology that requires high technical level and experience of operators. Operators need to master the principles of laser cladding, selection and adjustment of process parameters, etc. Otherwise, the quality of repair may be affected.
- The quality inspection of the cladding layer is difficult: The quality inspection of the laser cladding layer requires the use of professional testing equipment and methods, such as metallographic analysis, hardness testing, flaw detection, etc. The testing process is complex and costly. Moreover, there are still certain difficulties in detecting some internal defects and microstructures.
- Thermal stress problem: Although the heat input of laser cladding is relatively small, certain thermal stress will still be generated during the repair process. If the thermal stress is too large, it may cause deformation, cracking and other problems of the laminar flow roller matrix, affecting the performance after repair. Therefore, during the laser cladding repair process, appropriate measures need to be taken to reduce thermal stress, such as preheating, slow cooling, etc.
Is Post-Processing Required After Laminar Roller Laser Cladding?
Post-processing is usually required after laminar roller laser cladding for the following reasons:
1. Remove cladding defects
Although laser cladding technology can precisely control the cladding process, in actual operations, some tiny pores, spatters or unevenness may still appear on the surface of the cladding layer. These defects may affect the performance of laminar flow rollers.
For example, the pores on the surface may become stress concentration points, which can easily cause cracks during the operation of the laminar flow roller, leading to the peeling off of the cladding layer. Through appropriate post-processing methods, such as grinding and polishing, these surface defects can be effectively removed, making the surface of the cladding layer smoother and smoother.
2. Improve surface finish
Laminar flow rollers have high requirements on surface finish in many industrial application scenarios. For example, in the precision metal processing industry, the surface finish of the laminar flow roller directly affects the surface quality of the processed materials.
The surface roughness after laser cladding may not meet the actual working requirements, and it is necessary to improve its surface finish through post-processing methods such as mechanical processing to meet the requirements of the production process.
3. Eliminate residual stress
During the laser cladding process, the cladding material melts and solidifies rapidly, which will generate residual stress between the cladding layer and the substrate. These residual stresses may cause the laminar flow roller to deform or even crack. Residual stress can be effectively reduced through post-processing methods such as heat treatment, such as tempering.
During the tempering process, the structure of the cladding layer and the matrix will relax to a certain extent, allowing the internal stress to be released, thus improving the dimensional stability and mechanical properties of the laminar flow roller.
4. Optimize the cladding layer structure
The structure of the cladding layer after laser cladding may have some microscopic defects or unevenness. For example, the cladding layer may have problems such as coarse grains, which will affect the hardness, wear resistance, corrosion resistance and other properties of the cladding layer. Through appropriate heat treatment, such as normalizing or quenching-tempering treatment, the grains of the cladding layer can be refined and its organizational structure can be improved, thereby improving the overall performance of the cladding layer.
5. Dimensional accuracy adjustment
Laser cladding is mainly used to repair the worn or damaged parts of the laminar flow roller, but there may be certain deviations in the dimensions after cladding. In some applications that require high dimensional accuracy of laminar flow rolls, such as high-precision cold rolling processes, it is necessary to accurately adjust the size of laminar flow rolls through post-processing methods such as mechanical processing to make them meet the requirements of production equipment.
For example, the outer diameter of the clad laminar flow roller is processed to a precise size through processing methods such as turning or grinding to ensure the matching accuracy between the laminar flow roller and other components.