Primary Forming for Transfer Die

Primary forming operations create a part’s important forms, including:

• The primary form, that is, the largest EMBOSS form that is adjacent to the main surface

• Other EMBOSS forms (with no associated Lance GCD) that intersect the primary form or are adjacent to the main surface

• Other EMBOSS forms (with no associated Lance GCD) that are on the main surface and are shallow (in relation to part thickness)

• CURVED_BEND forms that intersect the primary form or are adjacent to the main surface

Following are the operations that perform primary forming:

• Drawing is only performed on a part if either its forms are not too shallow (compared to the aggregated form width) or it has a long flange. For such parts, Drawing is assigned to all the following kinds of forms:

o The primary form

o EMBOSS forms that intersect the primary form or are adjacent to the main surface

o CURVED_BEND forms that are adjacent to the main surface

For deep primary forms or curved bends, the number of required draws is calculated based on the form width reduction produced by each draw. The lookup table drawReductionPrecentage lists the percentage of the pre-draw width that remains after a given draw (that is, after the initial draw, first subsequent draw, second subsequent draw, and third subsequent draw) for a given material thickness. See also High Strength Material Derate Percentage.

• Crash Forming is assigned to all the following kinds of forms:

o Primary forms that are shallow (compared to the aggregated form width)

o CURVED_BEND forms that are adjacent to the main surface of a part that has a crash-formed primary form

o EMBOSS forms that are shallow (compared to the aggregated form width), provided the primary form is crashed formed

o EMBOSS forms on the main surface that are shallow (in relation to part thickness), provided the primary form is crash formed

• Pad and Wipe is assigned to a form only if the part’s primary form is not assigned to Drawing or Crash Forming (or the form has no primary form). For such a part, Pad and Wipe is assigned to the following kinds of forms:

o Downward CURVED_BEND forms that are adjacent to the main surface

o EMBOSS forms on the main surface that are either up features or are shallow (in relation to part thickness)

The following provides the cost model’s interpretation of some of the terms used in the explanations above:

• Adjacent: A form is considered to be adjacent to the main surface if the form bears a LIES_NEAR relation to the main surface, where the relation’s distance attribute is 0.

• Intersects: One GCD intersects another if one bears an INTERSECTS relation to the other.

• Associated lance: A form has an associated lance if the form is the smallest form that bears an INTERSECTS relation to the lance.

• On: A form is on the main surface if the form bears a LIES_ON relation to the main surface

• Long flange: A part is considered to have a long flange if its length is greater than a certain fraction of the part length. The fraction is given by the cost model variable flangeLengthPercentage (0.5 in starting point VPEs).

• Shallow (in relation to part thickness): A form is considered shallow in relation to part thickness if its depth is less than a certain fraction of the part thickness. The fraction is looked up by material type in the lookup table tblMaterialTicknessFactor.

• Shallow (compared to aggregated form width): To determine whether a form is shallow compared to aggregated form width, aPriori considers those EMBOSS or downward CURVED_BEND forms that intersect the primary form or are adjacent to the main surface. A form is considered shallow if its depth is less than a certain fraction of the aggregated width of those forms. (A part’s forms are considered too shallow for Drawing to be performed on the part if the largest such form is less than that fraction of the aggregated form width.) The fraction is specified by the cost model variable formDepthPercentage (0.15 in starting point VPEs). The post-forming width is estimated as the flattened forms’ SER widths minus the forms’ depths (the sum of the up and down depths).