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Dyn. viscosity (rheometer)

  
OELCHECK test instrument: Anton Paar Rheometer MCR 301, Nametre Viscoliner 1710
Sample quantity: Rheometer: ca. 2ml
Nametre: ca. 12ml
Unit: mPa*s
Test result: dynamic viscosity at various test temperatures
temperature range -30 °C to +110 °C at intervals of 10 °C
Brief description: In the Physica rheometer used by OELCHECK, a small quantity of lubricant (2 ml) is inserted into a precisely defined, tempered measuring gap between the rotor and stator. The rotor is driven by an engine with an air bearing. The oil sample in the measuring gap offers resistance against this rotation. This resistance is proportional to the viscosity, is captured via the resulting effect and is converted into dynamic viscosity.

To create the viscosity temperature profile, measurements are taken at intervals of 10 °C in the temperature range -30 °C to +110 °C. The measured values are available in table and graph form on the OELCHECK lab report and at www.lab.report.

Additionally, the kinematic viscosity can be calculated with the dynamic viscosity with a known density.
Statement:

For a slide bearing or gear unit, the kinematic viscosity at 40 °C and 100 °C does not usually constitute sufficient information to draw conclusions.

In order to design bearings, lubrication holes, pump pressures or tooth widths, a design engineer often requires the actual dynamic viscosity at precisely defined upper and lower threshold temperatures.

A common calculation method for viscosities is based on the viscosity index (VI) which is calculated with the kinematic viscosity at 40 °C and 100 °C. Especially for very high or low temperatures, the viscosity temperature profiles depending on the used base oil are usually not linear. Therefore, an extrapolation over the VI for a precise component design is frequently too imprecise.

With the Anton Paar Rheometer Physica MCR 301 we create a detailed viscosity temperature profile for the lubricant. With this information, a precise component design referring to the lubricant in use and the expected operating temperatures is possible.
Underlying test standard: DIN ISO 53019