Ink Doctor Blade Chipping And Streaking: Causes And Solutions

Ink doctor blade chipping and streaking are common problems faced by gravure printing manufacturers both domestically and internationally. These issues have consistently been a major factor affecting product yield. Of course, streaking is not solely caused by the blade itself; it can also be caused by environmental factors and the quality of the printing cylinder surface. Printing operators often adjust the blade pressure from low to high throughout the blade's lifespan. When streaking occurs, the problem is often addressed by cleaning the printing cylinder and blade, and increasing the blade pressure. However, this can reduce the lifespan of the blade and printing cylinder, consequently lowering the product yield. Solving these problems with the ink doctor blade is crucial. First, streaking caused by the blade itself is often due to the blade's flat angle. This requires increasing the blade pressure to adequately resist the resistance primarily from the ink. This increased contact area between the blade and the printing cylinder generates more heat, leading to increased blade wear. While excessive blade pressure may temporarily overcome the problem, it will reappear later. Sometimes the streaks are as fine as hair, sometimes as thick as wire, and in severe cases, the blade edge may even chip off in sections. This is mainly due to the blade's leading edge being lifted during overpressure printing. When we minimize all operational factors, we can summarize some solutions based on the problems encountered during printing. For example: 1. When the ink doctor blade shows fine streaks, it is often due to the blade itself, specifically its angle and pressure. 2. When streaks as thick as hair appear, it is often caused by ink particles. This is often accompanied by rapid wear of the doctor blade in the printing area (e.g., inks containing titanium dioxide). 3. When groups of very thick streaks appear, it is often caused by the viscosity of the ink. The role of the ink doctor blade affects printing quality. Different functions of the doctor blade have different effects on printing quality. Blade pressure, sharpness, and contact position with the printing cylinder all affect printing quality. Adjusting these factors appropriately according to actual needs can solve many printing problems. Let's now understand the different functions of the ink doctor blade. First, let's look at the pressure function of the ink doctor blade. The factors affecting the doctor blade pressure include the cylinder pressure, the type of blade (hard or soft), and the angle at which the doctor blade intersects the printing plate. A ​​larger angle results in greater pressure. Excessive pressure reduces ink transfer efficiency and causes significant wear on the printing plate and blade; insufficient pressure can lead to dirty plates or doctor blade lines.