Are your glue sets changed on a schedule or do you wait for production to complain about warped boards? Put another way: when was the last time you had your glue roll and metering rolls inspected? If you answered less than once a year, you may be wasting resources. The reasoning is straightforward: rolls today last longer than they did in the past, so upkeep takes on a new level of importance. Stick around for the next few paragraphs and I’ll explain why things have changed, what this means for your rolls, and why auditing can save you both time and money.
In the past, we have used mechanically engraved chrome for glue rolls and smooth chrome for metering rolls. We now know that chrome is very soft and not the best choice for a corrugator, so we have opted instead for sturdier materials. To that end, OEM corrugator manufacturers have recently been using mechanically engraved fused stainless steel for the glue roll, and either ceramic or sprayed stainless for metering rolls. Because stainless is significantly harder than chrome, these rolls will last much longer than the previous chrome rolls. This increase in longevity means that having them regularly inspected has become a very important task for maintaining print quality.
The upshot is that you don’t have to worry about downtime while your rolls are audited because Pamarco can now inspect your glue sets while the corrugator is down on preventative maintenance or on the weekend when the corrugator is not running. The process takes less than fifteen minutes per single facer and double backer by utilizing a powerful microscope camera. This service includes a detailed report showing the wear of your mechanical glue roll – all within a day or so of the audit!
The process of auditing the glue rolls is performed by an experienced Pamarco technical representative using the microscope we mentioned, and it provides detailed photographs that can be viewed on a laptop or even a smartphone. During the inspection, the representative will make marks at 10” intervals across the face of the metering roll. Once this is done, they will take a microscope photo at each of the marks; this will be performed on each single facer and double backer on your corrugator.
The representative will also visually inspect and provide feedback regarding any noticeable deformities on the metering roll, such as lines or gouges, that will eventually harm the metering roll or cause the use of a larger gap for the glue. After the inspection is over, you will receive your detailed report – in the form of a PowerPoint presentation – showing the results of the glue set audit with photos of each section and suggestions for any abnormalities based on what was discovered.
To give you a good example of what you can expect to see, take a look at photos below. Notice how each photograph shows different amounts of wear. As you can see in photos 1 & 9, the size of the cell wall is reduced to a point where the roll must be replaced as soon as possible. Photos 2 & 8 are showing signs of wear and a plan to change this roll within the next six months or so should be put into place. The photos taken from the middle of the roll are still in good shape and with preventative maintenance, should last for quite a while longer – barring any unusual circumstances, of course.
Many times, in the photos we take, the ends of the rolls show wear much faster than the middle. This is usually caused by the TIR of the rolls being out of spec. Just to clarify: rolls should always be 0.001 or less total indicated runout or TIR.
In this second example, 1 & 9 turned out not to be very good pictures, but overall, the rest of these are what a good roll should look like! Preventative maintenance would be the recommendation for these to last a good while longer.
Should you have any questions about auditing your glue sets or anything else related to corrugated, or if you would like to schedule an inspection, please reach out to your local Pamarco representative – let us save you time and money!