Numerical steady state prediction of spitting effect for different internal canalization geometries used in MQL machining strategy

• Multiphase flow was discussed and simulated for different channel geometries used to MQL milling process.
• We showed that imperfection in channel decreased the average outlet oil particle velocities.
• We showed that the increasing particle size decreased the average outlet oil particle velocities.
• We showed that the increasing particle size increased spitting effect outside the channels.
• We used high viscous oil which preserved small particle sizes.

The main goal of minimum quantity lubrication was to transfer an oil mist in a cutting edge via the inner channel of a cutting tool. But machining inner channels in a tool body provided imperfections on inner channel geometries. These imperfections have an effect on oil particle size making up the oil mist and then were studied in this paper. First, numerical simulations, of the oil mist in the channel were investigated by application of the Navier–Stokes and Lagrangian standard equations by integrating the standard k–ɛ turbulence model implemented in STAR CCM+ commercial software. This analysis showed the importance of maintaining small particle sizes and limiting imperfections which otherwise influence the performance of the micro spray and the effectiveness of lubrication. Experimental study was performed for the characterization of the oil mist in channels. The characteristics of the oil mist were defined as being particle velocities and sizes using optical laser methods and of consumption using the residual static gravimetric method. Comparison between experimental and numerical simulation results in the static validation step provided very good accuracy in terms of oil particle velocities as a function of the inlet pressure. Experimental results have shown the spitting effect at specific configurations as predicted with efficiency in the numerical simulation.