Tabbing for Punch Nesting

Tabbing – the processing of creating a material “bridge” between a part and its parent sheet of material – is important in both contour and punch nesting processes.  However, it takes on a special dimension in the punch process because of the means by which the tabs are created.

Punch tabs are often created as the result of space left between two punch hits.  Imagine two rectangular tool hits adjoining each other would create a continuous punched entity on the side of a fabricated part.  If two tool hits were spaced 0.012” to 0.030” apart, they would create a metal tab holding the part to the sheet.

Because tabs hold the parts in place while the remainder of the sheet is being punched, the turret can proceed without interruption from tip ups or loose parts.     By tabbing parts, the entire sheet can be removed at the end of the nest which avoids stopping the machine as each part is separated.

In some nesting software packages, the programmer needs to manually insert the tabs.  With hundreds of parts and possibly thousands of tabs, this can become a very time-consuming and error prone process.  One missed tab and you have the possibility of a loose part and a tip up (floating scrap).

By automating the tabbing process each part can be automatically tabbed and placed in a part library.   Complex tabbing rules make sure that there are not too many or too few tabs on each part.   These rules can also identify small parts that are dropped down a trap door and avoid all tabs on those parts   This process saves valuable programming time and effort and ensures that the quality of each part is consistent each time it is produced.

Special Circumstances

Sometimes parts require tabs in very specific locations.  There are often parts which have an edge that cannot have any burrs or indications of a remaining tab edge. A common reason not to tab on a particular side of a part is so residual burrs do not end up against a brake press backstop.  This could cock the part at a slight angle, putting the bend in the wrong place.  In these special circumstances, tabs can be assigned in a specific area on the part and locked in during programming.  In this case, a dynamically assigned tab would not be placed based on the shape of the part and its location on the nest.  The pre-assigned tab would override the automatic tabbing logic.

Tabbing of all parts also allow the sheet to be automatically unloaded using an edge grabber of suction cups to remove the sheet as a single piece from the machine.

For more information, contact Optimation.

Contact Optimation

Contact Optimation

Notice: This work is licensed under a BY-NC-SA. Permalink: Tabbing for Punch Nesting

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