What is a parting line in mold design in SW?
This is a theoretical line on the part that is used to create the parting surfaces. See previous answer. These are usually edges of the part.
I think someone has put up a tutorial? If not if I get a chance I will. However if you go to SolidWorks Tutorials they already have a tutorial on Mold which will lead you through the steps.
It helps to have an understanding of how molds are made in the first place.
Parting line is the witness line formed on the component at the intersection of the core & cavity parts of the component. When the component includes undercuts then the witness line around the split is also called parting line.