Cavity and Cut With Surface

Hi.

I have been using the mold tool functions in Solidworks 2009 andcan
make a mold on a complex part in a rather short time.
The problem is that it isn't flexible if changes appears on thecasted part during the project.
We work 100% with customer parts, so all parts in my mold designsare
imported from different cad systems.
If the customer sends a new part it's often quicker to start allover
with the inserts than to try and reimport it because of all errors.

Another approach would be to use the "older" cavity function in
Solidworks. When I try this I shut off all holes by extruding thinbosses.
Outer parting surface is created with planar, ruled, radiate and
lofted surfaces using the "split edges" on the part.

Everything works well until the cavity is made and it's time to cut
the part with my parting surface.
In 10 out of 10 cases, the "cut with surface" doesn't work and it's
failing because of "geometric condition".
The solution is often to extrude the parting surface about 0,2-0,5mm
into the cativy. Then it often works, but it takes a lot of time todo this extra step.
The problem is that the surface, created from the split line, goesall the way up to the cavity, but not into the cavity.

How do you handle this problem?
I'm running SW 2009 SP2.1 but this problem is the same also onolder
versions.

Thank you in advance for your answers


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