MACHINABILITY ENHANCEMENT OF STAINLESS STEELS THROUGH CONTROL OF BUILT-UP EDGE FORMATION / Demand for parts made from stainless steel is rapidly increasing, especially in the oil and gas industries. Stainless steel provides a number of key advantages, such as high tensile strength, toughness, and excellent corrosion resistance. However, stainless steel cutting faces some serious difficulties. At low cutting speeds, workpiece material and the chips formed during machining tend to adhere to the cutting tool surface, forming a built-up edge (BUE). The BUE is an extremely deformed piece of material which intermittently sticks to the tool at the tool-chip interface throughout the cutting test, affecting tool life and surface integrity. Unstable BUE can cause tool failure and deterioration of the workpiece. However, stable BUE formation can protect the cutting tool from further wear, improving the productivity of stainless steel machining.
This thesis presents an in-depth study of machining performance using different coated tools and various coolant conditions to examine the nature of the different tool wear mechanisms present during the turning of stainless steels. Then, different textures are generated on the tool rake face to control the stability of BUE and reduce friction during the machining process.
Results show that the BUE can significantly improve the frictional conditions and workpiece surface integrity at low cutting speeds. Finally, square textures on tool rake face were found to control the stability of BUE and minimize the friction at the tool-chip interface. This reduces the average coefficient of friction by 20-24% and flank wear by 41-78% and increases surface finish by 54-68% in comparison to an untextured tool. / Thesis / Doctor of Philosophy (PhD) / Three main objectives are presented in this thesis. The first is a detailed investigation of the performance of stainless steel machining obtained by the use of different coated cutting tools and various cooling conditions. The goal of this research is to assess the reduction of tool service life, productivity, and part quality. The thesis also examines the causes of workpiece material adhesion to the cutting tool during the cutting test and to better explain its effects on tool wear and workpiece surface finish. This phenomenon is known as the "built-up edge" (BUE). Finally, different textures are applied on the cutting tool via a laser to stabilize the BUE formation on the cutting tool, thereby improving the quality of the part.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/25393 |
| Date | January 2020 |
| Creators | Seid Ahmed, Yassmin |
| Contributors | Veldhuis, Stephen, Mechanical Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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