Multiphase modelling of cutting fluid and its aerosols in cutting simulations using the Finite Pointset Method (FPM) for analysing the mechanisms of action (MultiCuttingFluid)

• Applicants: Dr. Jörg Kuhnert; Professor Dr.-Ing. Martin Sommerfeld; Professor Dr.-Ing. Eckart Uhlmann
• Subject Area: Metal-Cutting and Abrasive Manufacturing Engineering
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 439626733

The mechanisms of action of cooling lubricant and their aerosols in machining processes are not yet fully understood. There are various theories on these mechanisms of action for a variety of influencing factors such as lubricoolant supply, process parameters or lubricoolant material properties. For example, the rinsing out of an insulating vapour layer, which forms due to the hot chip and tool surfaces, is assumed to be the cause of an increased cooling effect from a certain lubricoolant pressure. The positive influence of finely atomised lubricoolant spray mists in the case of low quantity cooling lubrication is attributed in part to dropwise evaporation. Even the elementary processes, such as droplet transport, droplet-droplet collisions, droplet collisions with hot surfaces and droplet evaporation within a spray mist are influenced by the MWF material properties, which changes the mechanisms of action. Using the mesh-free finite pointset method (FPM), these issues, among others, are to be analysed numerically within the scope of this project on the basis of three derived research hypotheses. The advantage of the FPM is that a fluid and structural simulation as well as the fluid-structure coupling can be simulated holistically within this method, even for large deformations. As a result, it has already been possible to model chip formation for a longitudinal rotary turning process with a single-phase fluid using FPM. Within this project, the existing cooling lubricant models will be expanded to include the vapour phase and spray mist as well as their physical mechanisms of action. The vapour phase will be implemented in the FPM. Elementary processes within a spray mist are taken into account by semi-empirical models of droplet interactions. The resulting multiphase modelling of the cooling lubricant and its aerosols is used to comprehensively analyse the mechanisms of action in the machining process. In order to achieve this objective, lubricoolant models and models of the mechanisms of action in relation to a vapour phase were developed in project phase 1. In project phase 2, these models and findings were integrated into the machining application in order to analyse the possible evaporation effects of cooling lubrication. In addition, the lubricoolant models have been extended to include the functionality of the spray mist in order to map the effects of reduced quantity cooling lubrication in the machining simulation in project phase 3. In addition, the simulation will be expanded to include tool wear in project phase 3. In addition to creating a general understanding of the process, the application of the validated lubricoolant strategies of conventional flood cooling, high-pressure lubricoolant supply and reduced quantity cooling lubrication in the simulation will enable targeted process optimisation.

• DFG Programme: Priority Programmes
• Subproject of: SPP 2231: Efficient cooling, lubrication and transportation – coupled mechanical and fluid-dynamical simulation methods for efficient production processes (FLUSIMPRO)