The cost model assumes that after forming has been performed, direct or cam trimming is required for blank edges that have tight tolerance—see Edge Trimming. In addition, holes that are accessible from the ram direction are direct pierced—see Direct Piercing. Holes not accessible from the ram direction must be cam pierced—see Cam Piercing.

Post-form trimming is triggered for edge segments whose positional tolerance is tighter than the threshold specified by the cost model variable edgeTrimmingPositionToleranceThreshold (2mm in starting point VPEs). If you haven’t specified the positional tolerance of an edge, the cost model assumes the tolerance specified by the cost model variable defaultPositionToleranceEdgeSegment (1.5mm in starting point VPEs). Note that all tolerances are bilateral; positional tolerance specifies the diameter of the tolerance zone.

In this example, the tolerance isn’t specified, and so is assumed to be 1.5mm. This is less than the 2mm threshold, so trimming is performed.

An edge segment can be direct trimmed if both the following hold:

Other edge segments must be cam trimmed. See Cam Bundling for Transfer Die.

You can customize what counts as sufficiently close to the ram direction with the cost model variable maxRamDirectionTangentAngle (30 degrees in starting point VPEs).

You can customize what counts as too close to vertical with the cost model variable minOpenAngleEdgeTrimming (3 degrees in starting point VPEs). And you can customize what counts as short enough with the cost model variable verticalTrimLengthThreshold (25.4mm in starting point VPEs.)

All edge segments in this example can be direct trimmed.

In this example, the holes on the top of the part are accessible from a direction that is sufficiently close to the ram direction, and so are direct pierced. The cost model variable maxRamDirectionTangentAngle (30 degrees in starting point VPEs) controls the threshold for both edge trimming and hole piercing.

Other holes must be cam pierced—see Cam Piercing.

The hole on the vertical side of the part is not accessible from a direction that is sufficiently close to the ram direction, so it is cam pierced. You can customize what counts as sufficiently close for these purposes with the cost model variable maxRamDirectionTangentAngle (30 degrees in starting point VPEs).

The same cam can do both trimming and piercing, and can generally handle both multiple edges and multiple holes, as long as all the features are accessible from the same direction. Cams are represented by CamBundle GCDs, and the Geometric Cost Drivers pane allows you to see which features each cam handles. See Cam Bundling for Transfer Die.

By default, aPriori assumes that the presence of cams does not require an IDLE station to accommodate extra space for the cam units. But you can override the default by enabling auto-inclusion of IDLE stations—see Enable Auto-Inclusion of IDLE Stations.