Tutorials > Workflow Tutorials > Part Processing and Importing a Solid STEP File

These options apply to a solid STEP file. They appear on the import bar only when the file being imported is a STEP file, so they are not offered for NC1 or any other format.

Unfold

A STEP file of a folded sheet metal part describes the part as it will be when it is finished - already bent. Before it can be cut it has to be flat. Tick Unfold and PrimeCut finds the bends, works out how much material each one consumes, and imports the flat pattern that will be cut to produce the folded part.

The fold lines are drawn on the flat pattern as marking geometry, so the operator can see where the part is to be bent. Each fold is labelled with the angle it turns through and the inside radius of the bend. The tick is remembered, so it stays as you left it for the next import.

Unfold setup

Unfold setup... opens the Unfold sheet metal window, which lists the material, its K factor, the thickness and the bends found in the part.

How much material a bend consumes depends on the K factor of the material. PrimeCut holds a K factor against each material, and there is a default for materials that do not have one set. If the flat pattern comes out slightly long or short, the K factor for that material is the thing to check.

Check the flat pattern before you cut it. Each bend is replaced by a rhombus when the part is unfolded. A bend that is a plain cylinder with flat or angled ends unfolds faithfully, but anything more than that - a hole or cutout running through the bend, a radius that changes along its length, a bend that is not a simple cylinder - is simplified to that rhombus, and detail in the bend region may be lost. The flat pattern is what will be cut, so it is worth looking at it against the solid before the part goes to the machine.

A part that is already flat, or that folds about more than one axis, is imported unchanged. Nothing is lost - you simply get the part as it was in the STEP file.