+44 (0)20 8600 9920
+44 (0)20 8600 9921
EHL (Elasto Hydrodynamic Lubrication)
/ Applications
EHL Ultra Thin Measurement System
The EHL System measures lubricant film thickness by optical interferometry. The sequence of pictures below shows an interferometric image of an EHL contact at increasing rolling speed and hence increasing film thickness. The lubricant film thickness at any point in the image can be accurately calculated by measuring the wavelength of light at that point. In practice the system measures the wavelength of the light returned from the central plateau of the contact and hence calculates the central film thickness.
EHL contact at increasing speeds
The images below show residual grease films deposited on the glass spacer layer disc of the EHL system. These images can be analysed to give information about the leakage process by which the rolling track is replenished with oil from the grease matrix. This work is part of an on-going programme of research using the EHL system in the Tribology Laboratory at Imperial College.
Residual grease track
Residual grease track
The two graphs below show central film thickness vs rolling speed at a range of lubricant temperatures. The first graph below is for an additive-free, 100 solvent neutral base oil.
Graph displaying an additive-free, 100 solvent neutral base oil.
The lower graph shows the same base oil with the addition of 10% wt of a viscosity index improver (dispersant poly(ethylene propylene) copolymer). There is a marked increase in the film thickness in the 15-30 nm range.
Graph displaying the same base oil with the addition of 10% wt of a viscosity
index improver (dispersant poly(ethylene propylene) copolymer).
