Looking for physics motor

[ByB]

Hello,

I am working on a project in which I have to be able to determinate
tools collisions during an industrial process.

My client is building objects by the use of automated tools (milling
tools & so on). The software I have to developp is supposed to be able
to check if the movements of tools are not going to cause collisions
between tools, or between a tool and the object being built.

For this, I suppose I could use a free (open source) 3D physics motor,
like those used for creating games, and let the motor check for
collisions. But I need a good 3D physics motor, able to check
collisions between modelized objects, and that can be programmed in C#
(maybe with the use of XNA ?).

Is this possible ? Do you know about such tools ? Thank you for any
suggestion.