2/21/2023 0 Comments High viscosity vs low viscosity![]() ![]() The best resource for mill coating information is the Technical Services department in most mills.įor more information on improving your coating process, contact your Valmet representative. ![]() At lower temperatures, the hydrogen atoms in the oleic acid. Table of rheology and associated problems AreaĬoating recipes vary by mill, so we don’t have specific information on them. The oleic acid molecules that are in olive oil are made up of carbon, hydrogen, and oxygen atoms. When a turbine-type mixer creates turbulence in the lower viscosity ranges (less than 5,000 centipoise), the resulting flow is chaotic. Coating rheogramsįigures 1 & 2 are illustrations showing how different types of coating recipes are affected by shear rate and the problems that can arise when viscosities get out of control.įigure 2 General guidelines for interpreting graphs (see area descriptions below) To better understand the ramifications of high-viscosity mixing, let’s first review a much simpler case that of turbulent flow in low-viscosity mixing. ![]() High high-shear viscosities can cause poor coat weight control, bleeding at the blade tip, and excessive blade loading, which can lead to poor runnability on the coater. It is a good indication of how the coating will respond to high shear rates under the blade tip. High-shear viscosity is not usually done on the coater, but performed in the lab when testing different coating recipes or investigating coater runnability problems. Brookfield viscosity is a good indication of coating solids, problems with the starch cooker operation, blade load pressure, coat weight control, and drying demand. It is a simple test but very useful for determining operation of the coater. Low-shear viscosity is the most often performed test in the control of the coating process. Specifically, in coating rheology, it is the measure of the resistance of a coating formulation to an imposed flow. On the other hand, if a fluid moves slowly, its. The viscosity of a fluid is said to be low if it moves quickly. Viscosity is the resistance of a material to flow. The ability of a fluid to flow is its viscosity. Coating rheology is measured with low shear (Brookfield) and high shear (Hercules) viscosity instruments. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |