In the '60s everyone was using 75 and 100 gauge films for packaging their retail products. In the '80s, only the braves ones reduced film gauge down to 60. Then in 2000, 45 gauge was introduced, and now we are extruding even thinner films with even better strength, durability, and cost savings !
In the '60s there was a 10% up-charge for centerfolded films because it required an extra step in manufacturing (simply folding it in half). Given that a customer would need to buy 48” single wound film, when they really needed 24” center folded, and given that a 48” roll weighs over 100 pounds, we provided our customers with mechanical center folders. These were free standing units that were placed adjacent to the sealing machine. This would allow our customer to literally fold the film themselves before it came into the sealer, bypassing that 10% charge altogether!
In the early days, shrink films were sealed using a round nichrome wire that was impulse-heated. When the seal-head came down, it would push a button, sending current through the wire. When heated, the wire would expand, then droop.
To remedy the drooping wire, a spring loaded "compensator" was created. As the heated wire expanded, the compensator would move to absorb the expansion. Initially a timer was used to control how long the wire was heated. As residual heat stayed in the wire, less heat needed to be introduced, which the timer did not recognize. The wire temperature would increase, often getting too hot. This would cause the film to burn, create weak seals, charring, and buildup on the wire and the seal pads. This would often be cleaned up using a wire brush or a screwdriver, obviously causing damage to the sealer!
The next improvement was a compensator with a thumb-screw adjustment to stop the flow of power to the wire once the wire had reached a certain expansion point which represented the attainment of sufficient heat. Even with a properly set compensator, an impulse system, which provided peaks and valleys of temperature, still provided many sealing problems, as listed above.
Treating the symptoms :
We have come a long way since the 60's, and there are more innovations in the industry that will continue to re-shape our packaging for a better, more sustainable, (and safer!) future. Do you have any good stories from your industry history? We would love to hear them, share them in the comments below!
If you are working with packaging equipment that is not meeting the standards you require, start a conversation with our Packaging Equipment team today!