Edge-finishing of granite workpieces by polishing is an essential mechanical process in the granite transformation industry that generates a given geometrical shape to the edge while maintaining a good surface finish and a gloss required by the customers. However, these polishing operations release significant quantities of fine and ultrafine particles that can penetrate by inhalation and deposited in the respiratory system of the workers when they are exposed to these particles for long periods. The accumulation of these particles containing crystalline silica (SiO2) in workers’ respiratory system can cause serious respiratory and lung diseases such as chronic bronchitis and pneumoconiosis called silicosis. The main objective of this work is to optimize this process by reducing the concentrations of dust generated while ensuring a surface finish that meets customer requirements.
Experimental tests on granite samples were carried out using a full factorial design in which polishing parameters were varied, in order to study their effects on dust emissions and on the surface finishes of produced edges. Two edge shapes were studied (chamfer and concave) using G150 (roughing phase) and G600 (finishing phase) grit size tools. The experimental design was applied on each configuration (Edge shape/Grit size) varying the following factors: spindle speed (1500, 2500, 3500 rpm), feed rate (500, 1000, 1500 mm/min) and lubrication flow rate (20, 40, 60 ml/min).
It has been shown that the effect of polishing parameters on particle emissions as well as on surface finish depends on the tool shape used and its grit size. An optimization of the process was able to bring out the best combination of cutting parameters depending on the desired shape and polishing phase, ensuring a good surface finish while minimizing dust emissions. Regarding lubrication, it has been found to be essential. The higher the MQL flow rate, the better the finished surface quality and the lower the concentration of fine particles, therefore wet lubrication is recommended.
| Date | 20 Jul 2022 |
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| Original language | French |
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| Awarding Institution | - École de technologie supérieure
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| Supervisor | Victor Songmene (Supervisor) |
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Bahri, H. (Author),
Songmene (Supervisor),
20 Jul 2022Student thesis: Master's thesis › Master in Engineering: Mechanical Engineering