Investigation of surface textured cutting tools for machining of medium carbon steel

Abstract

In the metal cutting process, the material is removed in the form of the chip by the sharp-edged cutting tool by the action of shearing. During this process, a significant amount of heat is generated, and intense friction is observed at the tool-chip interface. To reduce the severity of friction condition and heat generation, cutting fluids are generally directed at the tool-chip interface. However, cutting fluids often have an adverse effect on human health, and it is hazardous to the environment; moreover, the end user has to carry economic burden during usage and disposal of cutting fluid. Surface textured cutting tool is one of emerging techniques gaining attention recently for improving overall machining process which can enhance dry machining and minimum quantity lubrication (MQL) machining by eliminating or reducing the use of cutting fluids. Seizure conditions existed over the tool-chip interface contact where rake surface of cutting tool and chip are welded together followed by a sliding zone. At this seizure zone, gas or cutting fluid does not have access, however, at the sliding zone, gas or cutting fluid have limited access. It is the hypothesis that microcapillaries presented at the sliding zone help in providing access to the sliding zone. Thus, altering the tribological condition via exploiting capillary network can significantly affect the machining process. Therefore, the aim of the research is to enhance the microcapillary networks on cutting tool surfaces to ease the access of air and/or lubricants in environmentally friendly dry and near dry/MQL machining with the aim of eliminating or reducing the use of cutting fluids in metal cutting operations while maintaining or improving machined surface quality. The initial study confirms that surface textured cutting tools have the potential to be used in a machining operation. A more fundamental study involving orthogonal (two-dimensional) machining of AISI 1045 steel using uncoated carbide tools was conducted where the rake surface of the cutting tool is textured with a wide range of surface texture parameters. The study shows that a particular texture pattern is suitable for improvement in overall machining performance. The study further reveals that along with absolute surface roughness parameter, other surface parameters such as spacing, waviness and hybrid parameters of the textured surface of tools are also important playing a role in determining friction condition at the tool-chip and the tool-workpiece interface during machining and overall machining performance. The dry machining process is performed in a natural atmospheric condition. It was the hypothesis that various gases present in the atmosphere has an individual influence on friction condition at tool-chip and tool-workpiece interface. The study reveals that along with mechanical interaction, the chemical reaction also may take place at these interfaces and may have an influence on friction condition. Further, the study reveals that various surface texture parameters have control on access to air at the tool-chip interface, thus on friction condition. In the present study, a machining operation is performed in various gases, and its effect on machining performance is analyzed. Results suggest that various gases have differing influences on friction condition at the tool-chip interface and hence on machining performance. Workpiece surface quality is one of the critical parameters of machining performance. Orthogonal (two-dimensional) machining of AISI 1045 steel using uncoated carbide tools was conducted where the flank surface cutting tool is textured. The result shows that texturing flank surface affect surface roughness of machined workpiece. Further textured flank surface influence hardness along subsurface depth thus workpiece surface integrity. Finally, Challen’s wave model is analyzed to validate the one of the hypotheses that along with mechanical interaction, the chemical reaction also plays a role in determining machining forces. To make the first attempt, an empirical model is developed. Result suggests that with available data, cutting force and thrust force can be predicted, and further it confirms that various surface texture parameters play an important role in determining cutting and thrust force. In summary, information regarding the overall effects of surface textured cutting tools on machining performance of plan medium carbon steel is presented. Further, several avenues of future research are highlighted.