I am trying to export a rather complex geometry (a wire coil) to use in FEA, see image attached.
The coil is approximately 80mm in length of diameter 2mm with around 200 coils along the 80mm length.
When I export, however, the quality of the .step generated is too poor to be of much use. The coil appears as jagged edges instead of a smooth curve.
I can export as an stl in very good quality, however I am then required to convert it to a solid in order to import it into the FEA software which is time consuming and messy.
Can anyone suggest where/why I am losing the quality between the model and the solid part?
There are a couple of considerations:
Primarily, graphics quality may be lacking and therefore so is your perceived definition quality.
Other than that, I have seen a problem in early Creo 2.0 in how Creo dealt with seams.
On every helical sweep, at one full turn, it would not maintain proper trangency to the next segment.
This was fixed at some point (SPR retired) but I never followed up in Creo 3 and above.
In general, when you work with splines or resulting surface edges, you enter a world where precision becomes compromised significantly depending on the accuracy settings.
For your current work, I would suggest setting accuracy to absolute and in the range of .0005" or less.
Since you didn't specify why it needs to be solid, I'd suggest exporting a spline for the coil centerline and use it as a basis for a beam element in the FEA.
Also, what it looks like in a shaded image is not representative of the underlying precision. Try changing the shade_quality to a larger number in the config options. Also look at changing edge_display_quality to high or very_high.