Effect of MQL conditions on tool life in milling of AISI 316L stainless steel
Tunç, Lütfi Taner (2019) Effect of MQL conditions on tool life in milling of AISI 316L stainless steel. Journal of the Faculty of Engineering and Architecture of Gazi University, 34 (4). pp. 1665-1677. ISSN 1300-1884 (Print) 1304-4915 (Online)
Official URL: http://dx.doi.org/10.17341/gazimmfd.571466
In large-scale part manufacturing industries such as nuclear, aerospace and power generation, robotic milling is potentially a promising portable manufacturing technology to decrease the overall costs. The lack of enclosures around the robotic milling units blocks the use of flood coolant contrary to CNC machining centres. In such cases, the minimal quantity lubrication (MQL) technique is suitable, which on the other hand, agrees with the green manufacturing theme of the industry in the 21st century. However, the effect of MQL parameters such as the air pressure, oil flow rate, oil type, and pulse rate on tool life and surface integrity in end milling have not been well studied and understood yet. In this paper, the MQL technology is studied to understand its effects on tool life and surface integrity in end milling of nuclear manufacturing grade stainless steels such as AISI316L. The milling experiments are performed using a robotic milling cell. The tool life is assessed by measuring the wear land using optical microscopy techniques, whereas the surface integrity is assessed in terms of surface residual stress (XRD) and surface roughness (optical metallography). The results show that MQL conditions and the oil type significantly affects the tool wear, tool life and surface integrity. Improve surface roughness was observed at 15 strokes/min at 75 ml/h of fluid flow rate. It was observed that high stroke rate with increased oil flow leads to decrease in the surface residual stress. It was found that use of synthetic MQL oils do not help to increase tool life compared to dry cutting. When water-based synthetic oils were used, the stable wear progress duration was found to be very short.
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