8/6/2023 0 Comments Sae oil viscosity chart for f![]() By using three different viscometers, full flow curves of viscosity versus shear rate are obtained at several temperatures and fitted to various shear thinning equations. This paper describes measurement of the temporary shear thinning behaviour of a range of engine oil viscosity modifier (VM) additive solutions. It is well known that their blends exhibit shear thinning at the high shear rates present in lubricated contacts and that the resulting reduction in viscosity leads to thinner lubricant films and lower hydrodynamic friction than predicted in the absence of shear thinning. Viscosity modifier additives are used to increase the viscosity index of lubricants and are key components of most crankcase engine oils. In a companion paper, the master shear thinning curves obtained in this paper are used to explore how VMs impact film thickness and friction in a steadily loaded, isothermal journal bearing. This unusual response may originate from the presence on the VM molecules of two structurally and chemically different components. This fluid also exhibits extremely high viscosity index and shear thins more easily at high than at low temperature, unlike all the other solutions tested. One of the tested lubricants does not show this time temperature superposition collapse. ![]() This enables shear thinning equations to be derived that are able to predict the viscosity of a given oil at any shear rate and temperature within the range originally tested. It has been found that viscosity versus shear rate data at different temperatures can be collapsed onto a single master curve using time–temperature superposition based on a shear rate shift factor. This shows large differences in the shear thinning tendencies of different engine oil VMs. For example, an ISO 680 lubricant will have similar viscosity to an AGMA Grade 8 or SAE 140 gear oil.Viscosity versus shear rate curves have been measured up to 10 7 s −1 for a range of VM solutions and fully formulated oils of known composition at several temperatures. If you are used to working with one set of standards and suddenly get another thrown at you, this chart can provide a point of reference. So what’s the point of the chart? Basically, it allows users to determine whether or not lubricants will have similar viscosities. Listed below them are the viscosity grades for these standards. These are ISO Viscosity Grades, American Gear Manufacturers Association (AGMA) grades, SAE crankcase oil grades and SAE gear oil grades. The numbers in the middle will most likely look a bit more familiar. ![]() Still, it is commonly cited in lubricant product information. The measurement is specified by ASTM D2161, but is largely considered to be obsolete. ![]() ![]() These measurements refer to the results of a specific test producing measures of kinematic viscosity. On the other side, you have Saybolt Viscosities. Usually, these are tested at ☄0 and ☁00 Celsius and are almost always shown on product data sheets. It’s the most common unit of measure for viscosity and is expressed in cenistokes (cSt). It’s a measure of a fluid’s internal resistance to flow and shear under the force of gravity. Let’s take a closer look:įirst, let’s talk about kinematic viscosity. Viscosity grade comparison charts like this one are relatively easy to find, but they can be a bit difficult to understand. ![]()
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