Polyurethane (PUR) glues for book binding applications have increased in popularity over the past twenty years. They provide superior page pull strengths and desirable layflat opening characteristics.
Applicator nozzles and specially designed pots are used to apply the glue to the book. Both have advantages and disadvantages. Nozzles are closed systems, meaning the adhesive is not exposed to the air except when the nozzle is actively applying glue to the book. This simplifies startup and shutdown procedures and reduces overall glue waste. However, the sophisticated systems can be harder for operators to master and trouble shoot.
PUR pots work very similarly to EVA (hot melt) pots, and fundamental operating principles are easily grasped by novice binder operators. Specially designed coatings and components are required to prevent PUR glue from bonding to the application wheels and tank surfaces. Since pots are open to the air, they must remain in continuous operation, with only brief stops before the glue starts to bond and lose its effectiveness. Over time, the aggressive PUR glue takes its toll on the coated surfaces, and a cycle of scraping and sticking ensues until the pot cannot apply a consistent glue film. This can be remedied by taking the pot out of service and sending it to be resurfaced.
Every bad thing that can happen to a hot melt pot can happen to a PUR pot—but worse. That’s because the glue is so tough to remove and clean up. The pot can be accidentally overfilled, sending PUR into bearings and electronics where it doesn’t belong. Proper shutdown and cleanup procedures may not be followed. The cycle of heating and cooling can accelerate the normal wear and tear of regular operation. Fortunately, Muller Martini offers a convenient solution to all of these problems at our Certified Rebuilt facility in Allentown, Pennsylvania.
Experienced technicians in Allentown, using genuine Muller Martini parts and electronics, can restore even the most neglected and worn out pots to reliable operation.
For example, we recently received this PUR pot that had been, as we say in the trade, “ridden hard and hung up wet” a few too many times. Yes, that is a fire extinguisher in the lower left-hand corner of the photo. I don’t think its proximity to this pot is accidental.
After a few weeks at the Spa in Allentown, we returned this unit to the customer in like-new condition ready to produce a high-quality book for far less than the cost of replacing the gluepot, trolley and controls.
Contact us about our Certified Rebuilt program for gluepots. Your books and your customers will be glad you did.