Cutting Fluid Mist Formation and Behavior Mechanisms

Jichao Sun | PhD | 2004

Abstract:

The industrial hygiene community is paying ever more attention to cutting fluid exposure due to the negative health effects resulting from dermal contact and cutting fluid mist inhalation. Contact dermatitis and severe respiratory diseases including asthma, bronchitis, pneumonia, and decreased lung function may be caused by cutting fluid mist inhalation. In order to seek an effective method to control the cutting fluid mist, a thorough understanding of the formation and behavior of cutting fluid mist is desired. In this dissertation, analytical models are developed to characterize the cutting fluid mist formation and behavior mechanisms during a turning operation.

Firstly, an analytical model is developed to characterize the cutting fluid atomization on a rotating cylindrical workpiece by simultaneously considering three different atomization modes. The model is able to predict the mean diameter of droplets generated via different atomization modes in different circumferential regions.

Secondly, a gravimetric analysis and a GC/MS analysis are performed to analyze the composition of the cutting fluid vapor formed under high temperature. The cutting fluid considered in the present study is a 10% water diluted soluble cutting oil. It has been found that the mass concentrations of the organic compounds found in the vapor are much lower than the OSHA PEL standards. Further analysis of the vapor pressure also indicates that for the cutting fluid considered in the present study, vaporization/condensation is unlikely to occur.

Thirdly, a cutting fluid mist behavior model based on a non-equilibrium evaporation law, Raoult’s law, Stokes’ Law is developed to characterize the evaporation and settling of the cutting fluid mist. It is demonstrated that evaporation and settling can considerably change the size distribution of the cutting fluid mist. It is also found that the presence of the organic components in the cutting fluid slows the evaporation process and the cutting fluid mist becomes an oil mist under normal conditions.

Lastly, a cutting fluid mist formation and behavior model is proposed which can be used to predict PM10 mass concentration and droplet size distribution of the cutting fluid mist. The model predictions are also compared to the experimental data obtained from other researchers’ work. It is shown that cutting speed is the working condition that has the greatest effect on the mean droplet diameter as well as other mist related characteristics. The analysis also demonstrates the important effect that evaporation and settling have on the cutting fluid mist.

The models developed in this dissertation may be used to predict the PM10 mass concentration and droplet size distribution of cutting fluid mist generated under different working conditions during a turning operation. The models may also be used to produce inputs for further mist control analysis.

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