Application of Thermal Spray Technology in Printing Machinery Parts

       Thermal spraying technology has been used in printing machinery parts for many years, mainly plasma spraying, arc spraying and high-speed flame spraying ceramic coatings and cermet coatings. The main spraying materials are Al2O3, Al2O3+ TiO2, Cr2O3, Co-WC and stainless steel wire, etc. It is not only used for the repair of waste parts, but more importantly, it is pre-strengthened in the manufacturing process of new parts, giving the surface of the printing roller wear resistance, corrosion resistance, engraving, selectivity, wettability, insulation, non-stickiness One or more properties such as anti-static and anti-static properties to achieve the purpose of improving service life and its special functions. The main parts are printing rollers, laser engraving rollers, paper conveying jaws, intermediate embossing rollers, etc.



1) Laser engraving rollers are usually used on photolithographic printing machines. The traditional process method is to use copper electroplating or chrome electroplating, and then electro-etch the texture. Since the 1980s, it has been changed to plasma sprayed Cr2O3 ceramic coating, which is ground and polished and then laser engraved with anilox, so it is often called a laser engraving roller. Its salient features are: excellent wear and corrosion resistance, good hydrophilicity, clear and realistic printed images.



2) The printing roller is a basic component with a large amount of printing machinery and a wide area. The surface protection usually adopts methods such as Cr plating, Ni plating and Ni-P plating. Due to the existence of the porosity of the coating, the roller surface is corroded by the chemical additives in the ink and the environmental water vapor during the use process, resulting in pitting, pinholes and pits, which are likely to cause color smearing of the printed image and affect the printing quality. In order to further improve the service life and printing quality of the printing roller, the printing roller adopts arc spraying stainless steel series materials and high-speed flame spraying Co-WC series coating or plasma spraying NiCr combined with the bottom layer and Al2O3 + TiO2 working layer, which has excellent wear resistance and resistance. corrosion performance.



Arc spraying or high-speed arc spraying 2Cr13 or 3Cr13 stainless steel wire, coating thickness δ≥0.2mm, bonding strength ≥25MPa, porosity ≤5%, surface roughness Ra≤0.8um.



High-speed flame sprayed Co-WC series coatings, coating thickness δ≥0.15mm, bonding strength ≥70MPa, porosity <2%, surface roughness Ra≤0.8um.



Plasma spraying 50um NiCr combined with the bottom layer, and finally spraying Al2O3+ TiO2 ceramic composite coating, the total thickness of the coating is ≥0.3mm, and the bonding strength is ≥30MPa, which can significantly prolong the service life of the printing roller and improve the printing quality.



3) The paper conveying gripper adopts high-speed flame spraying or plasma spraying Co-WC series coating, and the sprayed surface maintains a certain surface roughness and has corresponding friction, which can greatly improve the service life of the gripper and ensure that the paper is not damaged. Injured, accurate delivery.