Factors Affecting the Amount of Adhesive Applied by a Plaster Coating Machine
Release time:
2021-12-17
The angle between the scraper and the tangent line at the point of contact with the anilox roller typically ranges from 15° to 30°. If this angle is too large, the scraper will almost touch the anilox roller directly. Since the surface of the anilox roller is not perfectly smooth, at high speeds, this can cause the elastic scraper blade to vibrate or jump, leading to splashing of the coating solution and resulting in uneven coating thickness and significant variations in coating weight. Moreover, an excessively large angle can easily damage the scraper blade's edge.
The coating amount of the plaster applicator is influenced by the following factors:
1) Currently, the blades used for scraping hot-melt adhesive on mesh rollers in scraper-type hot-melt adhesive applicators are mostly stainless steel blades. During coating, the pressure exerted by the blade on the mesh roller is too low. If impurities are present, the blade may lift slightly, creating gaps that result in uneven coating and increased coating thickness. Experimental results indicate that factors affecting the blade pressure include the hardness and flexibility of the blade as well as the scraping angle. In practice, the blade pressure should be adjusted using a pressure weight; typically, the blade pressure ranges between 200 and 400 kPa.
(2) The angle between the blade’s scraping edge and the tangent of the contact point with the anilox roller typically ranges from 15° to 30°. If this angle is too large, the blade will approach the top of the anilox roller, resulting in an uneven surface on the roller. At high speeds, this can cause vibrations or bouncing of the flexible blade, leading to solution splashing and uneven coating thickness, thereby causing significant variations in coating weight. Moreover, an excessively large angle can easily damage the blade’s cutting edge.
(3) The sharpness of the scraper blade primarily depends on the angle of blade wear, the purity of the solution, and the material of the blade. If the blade is new, a properly sharpened scraper should be able to effectively remove the adhesive layer from the anilox roller without producing any blade fibers. With moderate sharpness, the adhesive layer can be removed efficiently, resulting in a uniform and consistent coating with minimal variation.
(4) The scraper blade must be perfectly flat, with no warping or deformation, and the coating thickness must be uniform and consistent; otherwise, the coating thickness will vary significantly. The flatness of the scraper blade depends on how it is installed. Of course, impurities in the blade holder groove or on the blade itself can also cause issues. Therefore, when installing the blade, first clean the backing pad thoroughly, then place the new blade onto the pad and insert it into the groove. For the rotary-type blade-back screws, start by tightening them gradually from the center of the blade outward, alternating between the two sides. To prevent the blade from bending, tighten the screws in two to three stages. Use a cloth to hold the blade and backing pad together, then apply firm pressure while tightening the screws in one direction. By following this procedure, the combined scraper blade will achieve greater flatness, ensuring an even coating application.
(5) The left-to-right movement of the doctor blade plays an important role in improving the utilization rate of the blade and reducing wear on the roller caused by the blade. Considering this, the mesh wall experiences less wear, the mesh openings are deeper, and there is a greater volume of fluid, all of which help ensure that the desired number of coating layers is achieved. The left-to-right motion of the doctor blade effectively prevents the formation of water lines, resulting in a more uniform coating across the width of the substrate.
Relevant Blog
信惠科技（涿州）有限公司
Xinhui Technology (Zhuozhou) Co., Ltd
E-mail: xhkjzz@163.com
Mobile phone: +86-13911770565 Mr. Lin
Copyright © Xinhui Technology (Zhuozhou) Co., Ltd.
Powered by: 300.cn | SEO | Privacy Policy
