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Spray coating processing SPRAY PROCESSING
Anti-corrosion coating for drying cylinders
Pore sealing: For anti-corrosion coatings, pore sealing is absolutely essential. The choice of pore-sealing agent must be correct— it should have good permeability, high-temperature resistance, and corrosion resistance, and the application method must be appropriate.
Product Description
Supersonic Arc Spraying Technology for Papermaking Dryers
★ On-site ultrasonic spraying of stainless steel alloy onto the drying cylinder, followed by fine grinding and polishing.
★ Newly baked cylinder reinforced with high-velocity arc-sprayed nickel-chromium-boron wear-resistant alloy
★Spraying on the inner and outer walls of paper-making steam balls, coating rollers, and calendering rollers
★On-site brush plating repair for damage and corrosion on the drying cylinder, followed by mirror polishing.
The drying cylinder is a commonly used component in paper machines, and its surface condition directly affects the quality of the paper. The primary causes of deterioration in the surface condition of drying cylinders are corrosion and wear. Since drying cylinders are typically made of HT200—a material with a high carbon content—there are theoretically more corrosion cells formed, making it more susceptible to corrosion than ordinary carbon steel under normal conditions. At the same time, abrasion caused by pulp and its impurities, as well as uneven scraping by doctor blades, both leave scratches on the surface of the drying cylinder. Surveys indicate that most drying cylinders need to be reconditioned by grinding after just one year of use; for those severely affected by corrosion and wear, grinding may be required as frequently as every six months.
Regarding corrosion and wear marks on the surface of drying cylinders, most paper mills adopt cylinder-grinding treatments. However, repeated grinding significantly affects the strength of the drying cylinders and fails to address the underlying problem at its root. Some mills also resort to hard-chrome plating; yet, the chrome layer is thin and the cost is high, resulting in limited economic benefits. The supersonic arc thermal spraying technique represents a superior method for repairing corrosion and wear on drying cylinder surfaces. It boasts advantages such as high production efficiency, low costs, and minimal thermal impact on the workpiece, making it an important solution for on-site repair of drying cylinders.
Basic Spraying Process
The basic process for spray coating includes: surface leveling – degreasing – sandblasting to remove rust – spray coating – inspection (pre-acceptance) – pore sealing – acceptance.
1 Surface leveling: For new cylinders, this step can be omitted. However, for older cylinders in service, due to localized wear or corrosion that may result in pits or blemishes, it is necessary to use alternative methods to smooth or repair these areas. If there are localized old coatings, efforts should be made to remove them by sandblasting or grinding with a grinding wheel. In short, the surface to be coated should be roughly smooth, free of pits, and free of protrusions.
2、 Oil and Grease Removal: During processing or storage and transportation, new pipes may occasionally become contaminated with some grease. Use a cleaning solution to remove the grease, then blow dry and allow to air dry before proceeding to the next step.
3 Sandblasting for rust removal: Sandblasting shall be carried out according to a specified process procedure (see the technical section of the relevant tender documents for details). Sandblasting is a critically important process step. Its key points are:
● The air compressor must ensure sufficient pressure, with the blasting air pressure exceeding 6 kg/cm². The compressed air must be free of water and oil.
● It is best to use high-quality abrasives such as brown corundum and chilled cast iron sand. If quartz sand is used, it should be free of dust, angular, dry, free of impurities, and within a specific particle size range.
● Sandblasting requires a specific angle, a certain spray distance, and a defined sequence.
● After sandblasting is completed, loose dust should be promptly removed, and the interval between sandblasting and spraying should not be too long.
4 · Spraying: Spraying is the most critical process step; its key operational points are:
● Adjust the process parameters of the spraying equipment properly and ensure stable operation. Avoid frequent arc interruptions or conditions that do not meet normal spraying requirements.
● The spraying distance and spraying angle must be strictly controlled, as they significantly affect the coating performance.
● Spraying follows the principle of "spray from top to bottom, move leftward, and complete in sections," meaning: spray from top to bottom at a consistent gun speed, then reverse the direction and spray from bottom to top. After each pass, shift the spray pattern one step to the right. When you’ve moved about 1 meter to the right, return to spray in the opposite direction. Repeat this process several times (5–8 passes) to avoid uneven spraying or overheating.
5 Inspection (Pre-acceptance): The primary focus is on coating thickness, missed spray areas, and uniformity. If the appearance is uniform, with no warping, cracks, or flaking—no obvious visual defects whatsoever—the pores can be finally sealed.
6 Pore sealing: Pore sealing is essential for anti-corrosion coatings. The choice of pore-sealing agent must be appropriate— it should have good permeability, high-temperature resistance, and corrosion resistance, and the application method must be correct.
Prev: Equipment wear repair
Next: Offer metal powder coating, wear-resistant metal spraying, and wear-resistant metal coatings.
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Related products
Spraying equipment SPRAY EQUIPMENT
Anti-corrosion coating for drying cylinders
Pore sealing: For anti-corrosion coatings, pore sealing is absolutely essential. The choice of pore-sealing agent must be correct— it should have good permeability, high-temperature resistance, and corrosion resistance, and the application method must be appropriate.
Product Description
Supersonic Arc Spraying Technology for Papermaking Dryers
★ On-site ultrasonic spraying of stainless steel alloy onto the drying cylinder, followed by fine grinding and polishing.
★ Newly baked cylinder reinforced with high-velocity arc-sprayed nickel-chromium-boron wear-resistant alloy
★Spraying on the inner and outer walls of paper-making steam balls, coating rollers, and calendering rollers
★On-site brush plating repair for damage and corrosion on the drying cylinder, followed by mirror polishing.
The drying cylinder is a commonly used component in paper machines, and its surface condition directly affects the quality of the paper. The primary causes of deterioration in the surface condition of drying cylinders are corrosion and wear. Since drying cylinders are typically made of HT200—a material with a high carbon content—there are theoretically more corrosion cells formed, making it more susceptible to corrosion than ordinary carbon steel under normal conditions. At the same time, abrasion caused by pulp and its impurities, as well as uneven scraping by doctor blades, both leave scratches on the surface of the drying cylinder. Surveys indicate that most drying cylinders need to be reconditioned by grinding after just one year of use; for those severely affected by corrosion and wear, grinding may be required as frequently as every six months.
Regarding corrosion and wear marks on the surface of drying cylinders, most paper mills adopt cylinder-grinding treatments. However, repeated grinding significantly affects the strength of the drying cylinders and fails to address the underlying problem at its root. Some mills also resort to hard-chrome plating; yet, the chrome layer is thin and the cost is high, resulting in limited economic benefits. The supersonic arc thermal spraying technique represents a superior method for repairing corrosion and wear on drying cylinder surfaces. It boasts advantages such as high production efficiency, low costs, and minimal thermal impact on the workpiece, making it an important solution for on-site repair of drying cylinders.
Basic Spraying Process
The basic process for spray coating includes: surface leveling – degreasing – sandblasting to remove rust – spray coating – inspection (pre-acceptance) – pore sealing – acceptance.
1 Surface leveling: For new cylinders, this step can be omitted. However, for older cylinders in service, due to localized wear or corrosion that may result in pits or blemishes, it is necessary to use alternative methods to smooth or repair these areas. If there are localized old coatings, efforts should be made to remove them by sandblasting or grinding with a grinding wheel. In short, the surface to be coated should be roughly smooth, free of pits, and free of protrusions.
2、 Oil and Grease Removal: During processing or storage and transportation, new pipes may occasionally become contaminated with some grease. Use a cleaning solution to remove the grease, then blow dry and allow to air dry before proceeding to the next step.
3 Sandblasting for rust removal: Sandblasting shall be carried out according to a specified process procedure (see the technical section of the relevant tender documents for details). Sandblasting is a critically important process step. Its key points are:
● The air compressor must ensure sufficient pressure, with the blasting air pressure exceeding 6 kg/cm². The compressed air must be free of water and oil.
● It is best to use high-quality abrasives such as brown corundum and chilled cast iron sand. If quartz sand is used, it should be free of dust, angular, dry, free of impurities, and within a specific particle size range.
● Sandblasting requires a specific angle, a certain spray distance, and a defined sequence.
● After sandblasting is completed, loose dust should be promptly removed, and the interval between sandblasting and spraying should not be too long.
4 · Spraying: Spraying is the most critical process step; its key operational points are:
● Adjust the process parameters of the spraying equipment properly and ensure stable operation. Avoid frequent arc interruptions or conditions that do not meet normal spraying requirements.
● The spraying distance and spraying angle must be strictly controlled, as they significantly affect the coating performance.
● Spraying follows the principle of "spray from top to bottom, move leftward, and complete in sections," meaning: spray from top to bottom at a consistent gun speed, then reverse the direction and spray from bottom to top. After each pass, shift the spray pattern one step to the right. When you’ve moved about 1 meter to the right, return to spray in the opposite direction. Repeat this process several times (5–8 passes) to avoid uneven spraying or overheating.
5 Inspection (Pre-acceptance): The primary focus is on coating thickness, missed spray areas, and uniformity. If the appearance is uniform, with no warping, cracks, or flaking—no obvious visual defects whatsoever—the pores can be finally sealed.
6 Pore sealing: Pore sealing is essential for anti-corrosion coatings. The choice of pore-sealing agent must be appropriate— it should have good permeability, high-temperature resistance, and corrosion resistance, and the application method must be correct.
Prev: Equipment wear repair
Next: Offer metal powder coating, wear-resistant metal spraying, and wear-resistant metal coatings.
Online Quotation
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