Air convection during machining

[Vxxxxx]

Hi, I am conducting orthogonal cutting simulation of a temperature-sensitive material.
I am trying to lower the temperature of first deformation zone of my workpiece as the temperature from simulation is way higher than that of experimental results.
The machining experiment is conducted under room temperature.
I would like to ask if I should apply surface film condition on my workpiece. And what values i should use for film coefficient of air?
I can only apply on surfaces of my workpiece, so if chips form, there is no way to allow my machined surface/chips to interact with air?

Thank you.

 

[FEA way]

Yes, if you include heat transfer in your analysis then you should apply all necesssary thermal boundary conditions and interactions to your model. Especially convection that accounts for cooling of surfaces exposed to air. It’s difficult to determine accurate value of film coefficient but you can find some approximate values in various tables in literature. Usually a value from the range of 2-25 W/m^2*K is used for free convection with air.

 

[Vxxxxx]

Thank you FEA way.
How about the internal nodes that will be exposed to air only after being machined? (lower surface of the chip)

and if its still not enough to lower the temperature, is it okay if I just lower the value of inelastic heat fraction of my workpiece material? (currently 0.9)

Thank you.

 

[FEA way]

There is an option for that but only in Abaqus/Standard (check the documentation chapter "Thermal loads", paragraph "Specifying element-based film conditions on evolving faces of an element in Abaqus/Standard"). This feature is meant for additive manufacturing process simulations.

You can adjust the value of inelastic heat fraction if you need better match with experimental results.

 

[Vxxxxx]

Noted. Thank you so much FEA way!