Optimizing drilling cooling

Drilling process is one of the widest spread material removal process in the world. However, dealing with drilling coolant behavior can remain a challenging multiphysics issue.

The application

From the about 23,000 rivet holes of the Airbus A380 to the bone pin insertion orthopedic surgery, drilling is one of the most widespread machining processes. The thermal loading knowledge is a key point to ensure the workpiece integrity and the cutting tool durability. Indeed, one could check whether the coolant will not lose its lube feature or even change phase when drilling a metal part, while another would ensure the temperature of a drilled bone does not exceeded 47°C for more than one-minute to avoid necrosis.

Milling process simulation is very challenging since it requires multiphysics capabilities. Computational Fluid Dynamics (CFD) can help to simulate coolant behavior.

Our solution

 

Numerical simulation of machining process cooling may be challenging. Indeed, not only the machining tool complex geometry and fast shift must be accounted for, but also the coolant atomized free surface and thermal variation. A Lagrangian approach, as with the SPH-flow solver, can deal with such delicate case. 

The software has already proved it relevancy on through-spindle coolant. With such configuration, coolant, also called cutting fluid, is injected through the drill shank into internal channels down to the bottom of the drilled hole.

For simulating such case numerically, coolant has been injected through moving inlets, the heat production due to plastic deformation was modeled and transferred to the lubricant, and the fluid temperature signal have been scrutinized to lever up the process design. At this point, the material removal and the production of metallic chips are not simulated by themselves, but a coupling with a dedicated structural analysis solver could be undertaken. Under such assumption, the simulation has demonstrated the ability of the SPH method and the SPH-flow solver to deal with the drill coolant behavior.

Solvers