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How to Run Cover Stocks Through Folding Machine Rollers

[fa icon="calendar"] Fri, Nov 07, 2014 / by Andre Palko

folding-machine-attachments250One of the frequently asked bindery questions we get here is, “Don’t I need a special attachment like a Rotocrease to crease or perforate on my folding machine?” The short, simplified answer is, “No.” Based on the experiences of thousands of our customers, the majority of print finishing departments can successfully crease and fold cover stocks on their floor-model folding machines.

Yet as you probably know from your own experience, there is never a single, clear-cut answer to any given bindery issue. Such is the case with this topic. But with a little understanding of the limitations of machine and paper, combined with good technique, you can set reasonable, increased expectations for your bindery equipment.

In this case, the reasonable expectations for creasing on your folding machine are probably higher than you originally thought. Put another way, it’s likely you can produce a lot more, with less effort than you’ve been led to believe. Here are five tips that will help you to clarify these limitations and increase your expectations. (We’ll get back to attachments that bypass the fold rollers in a minute.)

1) In this recent video on How to Prevent Curled Cover Stocks, we show you how to overcome curling problems caused by fold rollers. The bigger your fold roller diameter, the thicker the sheet you can run.

For instance, on the MBO B-23 in this video, we're easily running a 14 point cover. On this and other folders similar to this I've run as heavy as 18 point. An MBO B-20, with its smaller rollers, will start to have problems when it gets above 12 point. Tabletop folders will struggle with anything above 10 point.

It’s easy to understand, the problem. Take a sheet of paper and try to wrap it around a small cylinder such as a pipe or small jar. A sheet of copy paper will wrap easily around the cylinder. Now try a piece of 20 point SBS or something else very heavy. Depending on the diameter of the cylinder, at some point the force need to wrap the sheet around the cylinder will cause the sheet to wrinkle or burst. The same thing happens with your fold rollers. That’s why printing presses that are designed for printing heavy solid board for the packaging industry use a straight travel path for the printed sheet.

2) The good news is that even the most severe limitation still leaves you with the ability to run a wide range of cover stocks through your folder. Here is another technique that is primarily designed to help improve register when creasing cover stocks. I learned from experience that it can also help reduce curl on very heavy sheets.

Now that we’ve got the paper to remain manageably flat, we need to be able to handle the folding. Folding multiple panels on a very heavy cover stock can be a bit tricky. For instance, a 15 point sheet folded two times as a 3-panel brochure has a total thickness of 45 points (.045”). A 4-panel sheet is .060” which is pretty darn heavy.

3) This is where we’ll find out the real limitations of the folder we happen to be running. Again, bigger rollers are better when it comes to thick stock. As a general rule, you also want to use the “bottom” fold plates when running cover paper. We discuss this idea here in another short article which diagrams the concept.

4) This article shows a very simple fold plate setup tip. It eliminates a big problem, usually self-induced, caused by operators who are in a hurry. (I know…what operator isn’t in a hurry!)

5) Lastly, one of the best ways to increase folder output is to run a job two-up and trim to final size inline. In my early years in the bindery, this was simply not done. Today however, with the right tools and setup techniques, it’s easy to do. This article shows two basic layouts for creasing and folding two-up jobs on cover stocks.

As a general rule, with the five techniques above you’ll find you don’t need an accessory for the majority, if not all, of your cover stock creasing work. Yes, there are exceptions to every rule. My point is that with the Tri-Creaser and Multi Tool on your folding machine, the odds are in your favor that you can successfully eliminate the extra step and extra work of attachments that bypass the fold rollers.

So before you add a Rotocrease attachment to your folder, let’s first see what the machine can do. With a little experimentation you’ll soon discover its true capabilities. And undoubtedly you’ll be pleasantly surprised at the new level of output you’ll come to expect.

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Topics: Bindery How-To Tips, Folding Machines

Andre Palko

Written by Andre Palko

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