The rapid growth in the application of lasers as a cutting tool has generated considerable interest in the quality of the cut edges produced. Consequently, the present study is conducted to assess cut edge quality, by defining the measurable variables, using international standards for thermal cutting. The measurable variables defining the cut edges may include waviness and flatness. Cutting speed, oxygen pressure, and workpiece thickness are considered as cutting parameters, therefore the Taguchi method is used to classify the relevant parameters. The study is extended to include the detection of light emission from the surface plasma. This makes it possible to monitor temporal behavior of the surface plasma, which in turn gives information about the formation of striations. Scanning electron microscope microphotography is conducted to examine the resulting cut surfaces. It is found that the cut quality is mainly affected by the oxygen gas pressure and cutting speed. However, flatness depends significantly on the thickness. Microcracks appear on the cut edge surfaces due to rapid solidification of the molten oxide layer formed on the surface.
SUMMARYIn the present study, an analytical approach governing the temperature rise in the solid pipe and #uid is presented. The entropy analysis in the #uid system due to heat transfer is introduced to obtain the integrated entropy generation in the system. Coolanol, water and mercury are selected as #uids while copper and steel are considered as pipe materials. In order to simplify the analysis, the heat transfer coe$cient at solid}liquid interface is kept constant during the calculations. It is found that the #uid temperature rise in the early heating period and the integrated entropy generation in the #uid system is lower in the case of a copper pipe.
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