Chapter 32: Using Plastic Features and Mold Tools
Using the Scale feature
The Scale feature is used to make the plastic part slightly larger to compensate for plastic shrinkage
during molding. Scale is driven by a multiplier value, so a part that is twice as big gets a scale fac-
tor of 2, and one half as big gets a scale factor of .5. Plastic materials have a shrink rate that is usu-
ally measured in thousandths of an inch per inch of part. Five thousands inch per inch is equal to
a 0.5 percent rate. If the part is four inches long, the mold cavity to produce it must be 4.020
inches with that material. The 0.5 percent rate is equal to a scale factor of 1.005.
Some materials have anisotropic shrink rates, meaning they shrink different amounts in different
directions. SolidWorks has a means to compensate for this, although it may not always be practi-
cal. Usually the shrink directions are identified as “in the direction of flow” and “across the direc-
tion of flow,” and the direction of flow of molten plastic inside a mold cavity is not always a
straight line. Any anisotropic shrink applied to a part in SolidWorks is an approximation at best. If
you deselect the Uniform scaling option in the Scale feature, SolidWorks enables you to set differ-
ent scale factors for X, Y, and Z directions. The Scale PropertyManager is shown in Figure 32.21.FIGURE 32.21The Scale PropertyManager
Insert Mold Folders
Mold Folders are folders that the Mold Tools add underneath the Surface body folders. You can
add these folders manually using the Insert Mold Folders button on the Mold Tools toolbar. They
are used to organize the different groups of faces used in separating the cavity and core solid bod-
ies. The folders that are added are
l Cavity surface folderl (^) Core surface folder
l Parting surface folder