OIL DROPS LEAVING AN EHD CONTACT

Many machine elements are lubricated with oil or grease. The flow of l ubricant depends on different parameters such as surface roughness, su rface energy, temperature, etc. A known problem with rolling bearings is that lubricants have to be refilled more frequently if a gas stream passes through the bearing. It is therefore important to I;now the be haviour of the lubricant in order to predict, e.g. bearing fatigue lif e due to a gas stream. By studying the droplets thrown out into the ai r after passing an elastohydrodynamic contact, the most important para meters for oil drop formation have been determined. The analysis is ba sed an picture processing and statistical methods. The experiments sho w that an increase in temperature, viscosity or surface velocity will increase the total drop volume. Decreased contact pressure and pure ro lling also increase the total drop volume. The volume flow, passing th e Hertzian contact area, varied between 18 and 30% of the air born oil -drop flow and it is reasonable to assume that increased flow of air-b orne droplets will decrease,the film thickness due to insufficient rep lenishment.