Printing roller surface coatings
Wear-resistant coating: The printing rollers, which are sprayed by Tungsten carbide coating, have the better wear resistance performance than the traditional chilled cast iron roller. The hardness of tungsten carbide coating can up to HV1300 equal to HRC 75. But hard chrome plating and chilled cast iron hardness can only reach HRC 65. Sprayed tungsten carbide coating wear resistance performance is 10 times than chilled cast iron. Tungsten carbide coating has 8GPa rolling contact fatigue strength which can bear the pressure of the calendering roller. Due to the dense and non-porous coating, the corrosion resistance is also better than the plating roller surface. The dense coating can be grinding to mirror finish, The tungsten carbide coating on the surface of ordinary steel rolls can prevent casting defects in chilled cast iron.
Hydrophilic coating: the oxygen acetylene flame ceramic coating used in the water roller. The hydrophilic performance is much better than the plating roller surface because the coating of this hydrophilic function is due to the ceramic coating with fine pores. Just like sponge structure, has great water absorption capacity which enhance the wettability of the coating and the uniformity is far superior to the smooth chrome plating layer. When the coating thickness is greater than 0.15 mm, the pores of the through-matrix can be eliminated, so that the coating does not peel off in a short time. In general, the coating of 0.25mm thickness is sufficient to give the roller a life of more than three years.
Anti-stick coating：Oxide ceramic and carbide ceramic coating is non-stick to the non-related properties of the material. The coating can be used in the drying area of the first dryer surface and also can effectively prevent the phenomenon of viscose. The wear resistance of the coating is much longer than that of the fluorine plastic anti sticking coating. This coating wear life is far greater than the fluorine plastic anti-stick coating and the anti-sticking effect is no less than plastic coating. Most of the surface of the printing roller is made of traditional hard chromium plating layer and because of the low hardness of the chrome layer, the scratches are often scratched on the surface of the chrome layer. The roller surface scars will affect the quality of glue. When doing HOVF spraying, the hardness of the coating is higher than chromium plating layer, and anti-adhesion effect is better than hard chromium plating. When scraper works, roller surface is not easy to be damaged and the roller surface working life is at least two times higher than hard chromium plating.
Anti-slip coating: large roll paper roller, because it is difficult to preheat, oxygen acetylene flame spraying molybdenum and carbide ceramics can’t reach high bonding strength, and the coating is easy to be polished. Using HOVF spraying carbide ceramics can overcome the above defects of spraying and can get dense, delicate, wear-resistant wool surface, and carbide ceramics have a high coefficient of friction, much better than molybdenum coating non-slip performance.
