During the operation of lathes and milling machines, very fine oil and emulsion mists are produced which are easily distributed throughout the entire production facility. The pollutants affect the health of the employees as well as the machines used and the quality of their products. With the help of compact electrostatic precipitators, the emulsion mist can be extracted and separated directly at the machine. The electrostatic separators ionise the finest liquid droplets so that they collect at the collector and can drip off. Compared to mechanical oil separators, electrostatic separators offer significant advantages in terms of maintenance and energy costs. However, during system operation, greasy deposits form on the separator surfaces, which reduce the separation efficiency and must therefore be cleaned at least every six months. Conventional cleaning methods such as brushes or high-pressure cleaners are unsuitable for this cleaning task because they compress the fine mesh of the pre-filters and after-filters and the narrow gaps of the collector cannot be reached by brushes. Cleaning in an ultrasonic bath, on the other hand, is gentle and intensive, even with complex components. Ultrasound is used to generate extremely fine cavitation bubbles, which remove deposits from sensitive and hard-to-reach areas in a time-saving manner. An added cleaning surfactant reduces the surface tension of the water and enables optimal cleaning results. In most production facilities for turned and milled parts, ultrasonic baths are already used to clean the processed products. The treatment of electrostatic filters therefore represents an additional benefit of the high-performance ultrasonic baths in production.