All fluid materials have what's called a viscosity. Viscosity is a fluid's measure of resistance to flow or gradual deformation, typically as a result of internal stress. Typically, the thicker the fluid material, the higher the viscosity. For instance, honey has a higher viscosity than water.
Viscosity is one of the most important characteristics when it comes to choosing specialty lubricants such as synthetics for metalworking and other projects. In fact, an oil's viscosity index was considered by up to 89% of lubrication professionals before a purchase, according to a recent survey.
Understanding the importance of viscosity
An oil's viscosity tells you how well it'll perform as a specialty lubricant. There are two specific types of viscosity to consider when choosing specialty lubricants: kinematic viscosity and dynamic viscosity.
Kinematic viscosity, which is a fluid's resistance to flow, can be measured in terms of centistokes (or cSt) and Sabolt Universal Second (or SUS or SSU). However, it must be noted that centistokes and Sabolt Universal Second are different units of measurement and therefore can't be compared when determining oil solutions. Depending on the grading system being used to determine viscosity, a fluid's kinematic viscosity can be measured at either 100C or 40C.
Dynamic viscosity, which is a fluid's internal resistance to flow, is typically measured in centipoises (cP). Kinematic viscosity can be described as a fluid's ability to retain shape as it's poured from a container. Dynamic viscosity is measured according to the energy it takes to move an object through the fluid such as a spoon. The higher the number of centistokes, SUS, and centipoises, the thicker the fluid and the higher the viscosity.
Determining viscosity for projects
A fluid's viscosity is essential when determining which type of oil or synthetic lubricant to use for a given project. This is because a fluid's viscosity is related to its ability to carry loads. If a fluid's viscosity is high, it can carry greater loads.
However, a fluid must also have a viscosity that enables moving parts to separate during operating conditions without trouble. Using a fluid that has too high a viscosity can be just as problematic as choosing a fluid with too low a viscosity.
Low viscosity can cause friction in the metal and an increased amount of oil consumption. High viscosity can also cause friction as well as reduced energy efficiency.
Therefore, the trick to finding the right specialty lubricants for the job is to find the right viscosity. Refer to the manufacturer's instructions regarding which viscosities are best used for your given machine or vehicle before contacting a lubricant oil distributor for further information.