INVESTIGATION ON THE PRODUCTIVITY OF MILLING TI6AL4V WITH CRYOGENIC MINIMUM QUANTITY LUBRICATION

Abstract

Because of its unique material properties, Ti6Al4V is used for components in the aerospace industry which are subject to high mechanical and thermal loads. Due to that, this material is considered as difficult to cut from a machining point of view. In order to improve productivity in machining Ti6Al4V the use of an effective cooling and lubrication strategy is necessary. This challenge can be managed with the innovative hybrid technology (CMQL) combining liquid carbon dioxide (CO2) and minimum quantity lubrication (MQL) being under investigation in this article. At first, investigations on the liquid CO2 release behaviour and the application of oil by the CMQL were conducted. Secondly, CNC milling experiments were carried out using carbide end mills. The CMQL technique was compared to MQL and flood cooling in respect to tool wear, cutting moment and surface integrity. For the milling operations the cooling parameters of the CMQL as well as the cutting parameters were modified, in order to reduce tool wear or increase productivity. The analysis revealed that the development of an appropriate CO2 free jet and a continuous application of oil by the CMQL is achievable without changing the state of aggregation of CO2 from liquid to supercritical. The analysis of the milling experiments indicated that CMQL is more advantageous compared to flood cooling and MQL for higher cutting parameters.