Check out our first Tribo Gatherings Podcast

We have started a Podcast! Our first guest is Dr. Connor Myant from Imperial College. We discuss biotribology, as related to the testing of food and hip joint failures. We discuss the advances in 3D printing and how Connor moved from Tribology into 3D printing. We discuss all Connors current projects and thoughts for the future.

The aim of this podcast is to discuss Tribology and related science, in a casual setting. If you think you would be a interesting guest and have a good story to tell – please get in touch.

Listen in through Spotify below. The podcast is also available on Apple Podcasts.

Preparing for the summer conferences 2023

We have been busy preparing for the conferences this summer.   By drafting some of our micropitting work for publication.  This will be presented at STLE, Lubmat and TriboUK.

We have been busy working on a rapid micropitting test that correlates to the FZG micropitting test.  Our new test takes less than 40 hours and correlates very well with the FZG test.  There are more developments to come, which we are excited about.

Micropitting screening test

We have also been busy designing and packaging our new freebies!  These are a lego wind turbine and electric car.  The wind turbine comes with a choice of colours for the flowers (pink, red or yellow), and the electric car comes with a minifigure!

A lot of our expertise is centred on the gearboxes in wind turbines and electric vehicles, so these seem like the perfect corporate freebie.  We hope everyone enjoys them. 

If you’d like one, just stop us at one of the conferences or get in touch.

STLE Annual Meeting and Exhibition

“Development of an Industrial Gearbox Relevant Micropitting Test”

Session: Gears I.  11:30 am on Tuesday 23rd May in room 103B.

Lubmat (Preston, UK)

“Development of a Rapid Micropitting Test for Industrial and Automotive Gearbox Lubricants


“Development of a Field Relevant Micropitting Test”

We also plan to attend the BioTribology conferences in September.

Traction Curves

Traction curves can be used to develop lubricants for specific applications, for example high traction fluids for CVTs.  They can also be used to help understand the physical changes of the lubricant under high contact pressures.  This can then be used to help develop new lubricants with special properties, for example with low traction to help in machine efficiency.

The measured traction depends on the physical properties of the lubricant in the central film area.  Under EHD conditions the lubricant film experiences high pressures and high shear rates momentarily.  Traction curves gives an approximation of how the EHD film shear stress varies with strain rate.

An example of a idealised traction curve is shown below:

traction curve diagram

At lower SRRs the strain rate is small and the fluid is considered Newtonian.  Hence as the proportion of sliding increases, so does the strain rate along with the shear stress of the fluid.  This results in an increasing measured traction.  This is the linear region.

At higher SRRs the strain rate becomes significant, resulting in shear thinning.  The shear stress of the EHD film cannot exceed a critical value called the “limiting shear stress”.  This results in the levelling out of the traction curve, indicated by the isothermal region.  The limiting shear stress is dependent on the molecular structure of the lubricant.

The example of a traction curve below uses a high traction fluid – Santotrac 50.  This fluid consists of a high traction cyclic hydrocarbon structure.

Traction curve example - Santotrac 50

Traction curves can be used to compare the EHD traction of different base oil formulations.  This type of measruement can be linked to machine efficiency.  The plot below shows some traction curves formed by engine oils, with different base oil composition.

Traction curve - base oil effects

As the traction curves are lowered, a gain is expected in machine efficiency – especially those with a large number of non-conformal EHD contacts.

Traction curves are also used frequently in rolling element bearing research.  The traction forces in the bearing influence the fatigue performance of the surface.  Traction curves can be used to find suitable lubricants and greases to reduce the shear forces on the bearing surfaces, extending their lifetime.

We can conduct traction curves in the following test envelope:

Temperatures: ambient – 150 °C

Speeds: 0 – 4 m/s

Contact pressures: Up to 1.25 GPa with steel specimens (up to 3 GPa with WC)