Many CNC cutting machines can only take arcs and linear segments. My method is to use DraftSight, the free software affiliated with Dassault and Solidworks. With DarftSight, it is a question of transforming the curves of spline or even Bezier type into polylines then of converting them into tangent arcs. Solidworks does not get the dxf with tangency relationships but the arcs are tangent. It might be wise to create blocks to make sure they are fixed.