Effect of minimum quantity lubrication (MQL) on fine and ultrafine particle emission and distribution during polishing of granite

Granite polishing generates aerosols containing fine and ultrafine particles that can be detrimental to occupational health and safety. As the occupational safety regulations are becoming more and more stringer, it is important to find ways of limiting the workers exposure to these particles. Different methods have been proposed to reduce the dust emission at the source during polishing of granite. They include using ventilation to capture or redirect the dust and using of wet polishing process to help settling down quicker the generated particles. Traditionally, the wet machining processes are conducted using flood lube but given the costs associated with this lubricating condition, in most machining sectors, the use of minimum quantity lubrication or cooling, also known as MQL machining is being tried. MQL polishing could be a cost effective way of reducing the dust generation at the source when polishing granites. Knowledge on the distribution and behavior of semi-wet particle could also help in designing other methods and apparatus for capturing or taking the dust away of the working environment. This paper investigates fine and ultrafine particle emissions during polishing tests under minimum quantity lubrication (MQL) conditions as compared to dry polishing. The MQL polishing is done using water at different flow rates and their effects on the working environment air quality investigated. It is found that the effectiveness of water MQL in particle reduction depends on size of particles considered.