The Ingram-Roots method allows lubricant formulation to be rated quickly and accurately using an MTM2.
The lubricant viscosity is used to calculate the most appropriate speeds and running time on the MTM test. The oil performance is then rated, using the normalised Stribeck curves. This is done at two temperatures: 40 and 100 °C.
This helps people who are less experienced in tribology to quickly assess their formulations.
The method was developed between the years 2018 and 2021 and was found to be repeatable and reproduceable for a selection of oils (from 0W15 engine oils to ISO VG320 industrial gear oils).
The test method is used to give each oil 5 ratings:
𝑅𝑀40 – Rating at 40 °C, Mixed Regime
𝑅𝐸𝐻𝐷40 – Rating at 40 °C, EHD Regime
𝑅𝐵100 – Rating at 100 °C, Boundary Regime
𝑅𝑀100 – Rating at 100 °C, Mixed Regime
𝑅𝐸𝐻𝐷100 – Rating at 100 °C, EHD Regime
The formulator/ engineer can decide on the most appropriate measure to use. This will be based on the end application of the lubricant. The rating can then be used to easily compare the performance of different oils.
The following 15 oils were rated using the Ingram-Roots Methods:
An example of the raw Stribeck curves for 15 oils at 40 °C and 100 °C along with their subsequent ratings are shown below:
Stribeck Curves at 40 °C
Stribeck Curves at 100 °C