Scaling Factor and
Draft in Mold Design
Scaling Factor
When you create a mold you must account for the scaling
factor. The scaling factor is the amount the material in the mold
shrinks or expands as it solidifies. The scaling factor depends on the
type of material used and the shape of the mold, and is expressed as a
percentage of the linear size (not volume) of the design part.
The software scales the cavity by the specified scaling factor, using
this formula:
Cavity size = part size * (1 + scaling factor/100)
For example:
Desired
adjustment |
Scaling factor in %
(enter this number) |
Resulting
cavity size |
2% material shrinkage (cavity larger than part) |
2.0 |
part size * 1.02 |
2% material expansion (cavity smaller than part) |
-2.0 |
part size * 0.98 |
Creating Drafts for Molds
You may need to add draft angles to molded
design parts to make it possible to remove the finished part from the
mold.
If you have a SolidWorks model, you can use
the Split
Line tool to split faces and the Draft tool to add
draft. You can also used the Ruled
Surface tool with either SolidWorks or imported
models to add draft, correct flawed surfaces, or create interlock
surfaces.