Abstract：

This paper taking eight typical machining workshops as research objects, combining with the production processes, analyses the oil mist emission characteristics and control means. The oil mist concentration in the workshop is continuously measured, the relationship between the oil mist concentration in the breathing area of the post and the production process is analysed, and the oil mist control effect of the ventilation means and purifiers in the workshop is investigated. The results show that during production, ventilation has a significant effect on the removal of oil mist particles with a particle size from 5.0 to 10.0 μm, and the number of oil mist particles in each particle size section does not change significantly with the air changes per hour, the local exhaust air located above the machine tool still does not ensure that the oil mist concentration in the breathing zone of the post is lower than  the recommended value of the National Institute for Occupational Safety and Health (NIOSH), and source control of oil mist emissions is critical, purifiers can be effective, but at the same time increase the operational and maintenance management and cost requirements of ventilation system. In the analysis of the measured data, it is found that the oil mist escaping outward through the gap of the closed machine tool operation door cannot be ignored, and its escape rate is directly related to the pressure difference between the inside and outside of the machine tool and whether the resulting gap flow rate is greater than the particle spillage rate, which is worth in-depth discussion.

Keywords:machining workshop; oil mist; concentration; ventilation; purification; production process