Abstract
Used lubricant for precision mechanical machining includes a considerable amount of very fine metal particles. Incorporation of the fine particles is a factor of the deterioration of the lubricant. If it were possible to remove the particles effectively, the used oil could be reused. Many attempts have been done to remove the metal particles using several methods, i.e., sedimentation, filtration and centrifugation. Since the viscosity of the used oil is quite high, those methods are not suitable to separate metal particles thoroughly. We found that the metal particles migrated under the high electric field and aggregated on the electrode. After the treatment by the high electric field, the transmittance value recovered to about 75% of that of the original oil. The kinematic viscosity of the treated oil was almost the same as that of the virgin oil. The chemical structure of the cutting oil and additives were hardly degraded by the regular use of the lubricant and the treatment of high electric field. The application of the high electric field is a useful method to remove the metal particles effectively.
