Purdue University

Purdue University

Mechanical Engineering
Tribology Laboratory

Optical Ball on Disk Machine

The optical elastohydrodynamic (EHL) ball on disk machine is used to measure lubricant film thickness under various operating conditions.  The test rig is currently being used to measure pressure, temperature, and lubricant film in EHL contacts.  It has a coated transparent rotating disk which is in contact with a steel ball that is partially submerged in a retainer of lubricant.  By using interferometry techniques, the film thickness can be measured by viewing different color patterns that appear in the contact through a microscope.  This is useful for investigating film thicknesses of lubricants under various contact loads and speeds.  The glass disc can also be RF sputter coated with appropriate metallic and ceramic coatings.  Photolithography is then used to develop sensors which can be used to measure in-situ pressure and temperature in EHL contacts.


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CAD Drawing of the EHL Machine   EHL Machine


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Lubricant Film Generated Between the Ball and Disc

  Closer Look at the Ball on Disc Contact Area

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