Precision Label Placement for the Impossible Application?
Imagine a label of approximately 50 x 75mm in size. Now imagine that the label includes four small holes, one near each corner of the label. The small holes are less than 2mm in diameter. Now factor in that the label manufacturer only ‘guarantees’ that those hole positions will be maintained with a tolerance of +/- 0.2mm through the die-cut process. Got it? Finally, realize that the customer requires the label to be applied to their substrate such that those 2mm holes line up to 2mm holes on the substrate with a tolerance of 0.1mm concentricity! Impossible, right? Our PL Series of applicators are proven to provide very tight tolerance and very tight placement repeatability (as good as +/- 0.05mm) but if the customer requires a 6 sigma process with alignment of all four holes how can our system possibly provide a success?
The answer: through creativity and a focus on delivering a successful result. Yes, we did have an application exactly as described and yes we did deliver a successful system implementation using our PL Applicator with the EP package for Extreme Precision. But we also used ‘outside of the box’ thinking to bring it all together.
In this case we used precision locate pins to fixture the substrate at the four critical locations. The pins were a slip fit to the substrate and incorporated a lead-in feature to allow easy loading of the substrate. The PL Applicator, by its standard process, was used to feed and peel the label from the liner. We added the ‘twist’ as we describe next. The PL Tamp extends the label down to a position less than 1mm above the substrate. Since the PL Applicator always feeds the label very precisely we can be certain that the fixture locate pins, which incorporate a slight lead-in and extend more than 1mm above the surface of the substrate, will enter the corresponding holes on the label. We included clearance holes on the vacuum chuck so that there would be no interference with the pins. We then turn off the vacuum, allowing the label to ‘fall’ onto the pins so that it is automatically aligned perfectly concentric to those pins. We then allow the Tamp to extend the additional 1mm so that it presses the label down onto the substrate. A slight amount of flexibility in the label allows it to conform to the locations that we have physically dictated by use of the pins. Not only that, but the substrate and label are easily removed from the fixture even with the tight tolerances.