Cryogenic cooling for machining cast iron materials using PCD tools

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The current and still rising trend for the application of high-strength materials like compacted graphite iron (CGI) leads to increased requirements concerning the design of effective future cutting tool systems and machining strategies. Referring to state of the art a high potential for the use of the cryogenic cooling media CO2 in combination with a polycrystalline diamond tool (PCD) could be figured out as high effective to machine CGI under continuous cutting conditions.However, basic effects and holistic interdependencies of the CO2 cooling parameters (e.g. CO2 mass flow rate, nozzle distance, angle of attack, number of nozzles, combination of CO2 and MQL) onto the operational behavior of the PCD tool and the material properties of the work piece have not yet been studied in detail. It could be assumed that especially the CO2 flow rate can be reduced significantly to machine more economically friendly.The aim of this project is to analyze the impact of the CO2 cooling parameters onto the thermo-mechanical load spectrum of PCD tools for continuous cutting processes of CGI materials. Previous findings in this area can be completed.To clarify the influence of the CO2 cooling parameters onto the collective of load the following approach is intended. In particular the cutting forces and temperature as well as the chip formation and the specific wear mechanisms will be analyzed to quantify the influence of the CO2 cooling parameters onto the thermo-mechanical load spectrum. The focus of the analysis is to determine a customized cryogenic cooling strategy setting a minimal amount of CO2. Besides basic machining experiments fundamental material science tests will be performed. The effect of the CO2 cooling parameters onto the load spectrum and finally the operational behavior can be identified in detail. The relevant mechanisms can now be understood in detail. The findings will be transferred to a systematic mathematical evaluation of the machining process in order to derive recommendations for practical applications.At the end of the first part of the project a customized CO2 cooling system concerning the specific load collective of the PCD tool will be developed to suppress the temperature induced wear mechanisms during machining of CGI. Within the second part of the project the transfer of the findings will be focused. Therefore, further ferrous materials will be machined using different PCD tools. Finally environmental and economic studies will be accomplished to get a holistic view onto the cryogenic cooling system. The interdisciplinary goals of this project allow to bridge an important gap regarding the impact of the CO2 cooling strategies onto machining applications using PCD tools.