Part VII: Working with Specialized Functionality
- Use the Cavity or Core knitted body to trim the extruded surface.
- Use the extruded surface to trim the ruled and lofted surfaces.
- Knit the surface bodies together.
FIGURE 32.27A part that requires passing shut-offs.
The hardest part of creating this passing shut-off is visualizing what the interface between the steel
from opposite sides is going to look like. It is best to keep it as simple as possible. Tool builders
request a wide range of angles for the passing shut-off (mold steel touching at steeply angled faces).
I have heard them say that the minimum draft they can possibly stand is anywhere from 5 to 15
degrees of draft. I try to give at least 8 degrees, and more if I can. The tool builder will also look for
a minimum land on the top of the shut-off boss, generally not less than 1 mm, or approx 0.050
inches, to work with round numbers.Don’t be discouraged if you don’t completely understand this the first time around. The concept
itself is difficult, and visualizing the geometry is extremely difficult.Non-planar Parting Surfaces
Frankly, the method SolidWorks uses to create the Parting Surface is insufficient for most tasks. It will
work well if you are molding a range of Frisbees or dinner plates, but it will not work well for handheld
medical devices. Figure 32.28 shows the part on the CD-ROM named Chapter 32 – frame parting
surface.sldprt. The result is entirely unacceptable for several obvious reasons.From this you can learn that the SolidWorks Mold Tools are not reliable for concave parting lines
or non-planar parting lines. Flat parting line disks and boxes work well. Beyond that, expect to
need to do some manual surface modeling.