The user guided IM cost model uses four undercut depth values in order to estimate costs associated with slides. (The GCD-driven injection molding model, in contrast, analyzes the geometry of each undercut and determines how many slides are required and which undercuts each slide handles.)

You must enter this information by using the PSOs described below, which are associated with the routing node Injection Molding.

Each of the four inputs corresponds to one of the four walls of your part’s bounding box. These four walls are the sides of the bounding box that enclose the part about parting line, in other words, the sides on which an undercut might open. Each side has an associated direction, the direction from which an undercut on that side would be accessible, that is, the direction from which a slide for the undercut would approach. The directions are named for a coordinate system whose axes run along the part’s length and width (see Part Length, Width, and Height):

There is an undercut depth PSO for each of these directions:

Undercut depth for a particular side is the distance from the deepest point of the deepest undercut on that side. The depth is measured to the first point that is accessible from the draw direction, in other words, the edge of the shadow that would be cast by a light projected from the draw direction.

Mold size increases as undercut depth increases. Note that the increase in mold size is significantly greater than the undercut depth, since a slide mechanism is considerably larger than the largest undercut it handles—see Mold Dimensions for more information.