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Recover, Don't Regrind Your Folder Rollers

Recovering and reknurling your rollers adds life to your valuable folder rollers.

So, your folder is running slower and slower these days, and you can't get a tight fold with slow speed. You've put tape on three of six rollers to add some friction, but you still can't get the rollers to run up to speed. You know you need new rollers before you can run that big job, but after calling around for quotes you don't think you can afford it. The big job won't even pay for the rollers -- you bid it on the low side just to get the work. What options do you have that will enable you to produce a quality print and fold job and still make a profit?

Whatever you decide, please don't regrind your rollers.

Some bindery supply companies promote regrinding as an alternative to purchasing new rollers, or a less expensive way to "recondition" a used roller. They even go as far as to describe this technique as extending the life of your rollers and returning them to OEM specifications. Don't believe it. It may appear less expensive in the short term, but regrinding shortens the life of your roller and the end product fails to match OEM standards.

We have been asked hundreds of times over the years if we "regrind" rollers. The answer is no, definitely not. At FolderRollers.com, we recover rollers, we don't regrind. Likewise, when you purchase our exchange rollers, you are receiving recovered rollers that are guaranteed to match your machine. We proudly post our prices on our website www.folderrollers.com for you to compare our services with other bindery suppliers. But don't compare recovery with regrinding; they are not the same. Suppliers who offer a regrinding service -- who, by the way won't publish their prices but require you to call them and ask for pricing -- might be able to save you $20-30 at the most. But this is a short term gain and a longer-term loss.

As you probably know, your roller cores, with appropriate care and maintenance to keep the metal knurls from receiving excessive wear, will provide many years of service in your folding machine. When new rollers are not an absolute requirement, recovered rollers, in which the urethane is completely replaced, are the best alternative. Here's why recovery is better than regrinding:

When rollers are reground, a portion of the total diameter of the roller is removed, including both metal and urethane. The roller is ground to the point where the top of the knurl teeth across the roller been touched. When your rollers are returned to you after regrinding, they will look great, but they will be on the low side of the OEM spec or below. At the middle of the roller, the knurl tips have been only touched by the grinding operation, while at the ends of the roller the knurls have been erased. Rejuvenation of the urethane has not taken place at all. You may be back up and running again on the cheap, but not at OEM specs, and not at fast speeds that can be maintained. We will explain further.

Don't forget, the reason you need to recondition your rollers is because there is minimal grip of the paper. Loss of grip is caused by two things: first, roller urethane is worn down in the center of the roller and won't grip the paper evenly from end to end; and second, the urethane has lost its "come-back" quality (it doesn't come back after being pressed) and has become hardened, deteriorated, cracked, or even missing. The hard shell or glaze on the urethane is caused by age and abrasion (one customer described his old urethane as looking like "bakelite"). In most of the rollers we see at FolderRollers.com, the urethane is well below the diameter of the steel knurls (teeth on the steel).

Bindery suppliers who regrind rollers with hardened urethane try to figure out how much more urethane can be removed from the roller while still allowing it to run paper, without regard to specs. Urethane is removed to eliminate high and low spots, as well as to remove the outer glaze and rejuvenate the urethane. With the outer glaze being as much as .010" deep, regrinding will remove at least .015" urethane to create "fresh" grip. As you can imagine, this process causes the rollers to become undersize, as much as .010 to .012" less per side than the original diameter when the roller was new. But with most used rollers that have lost their grip, the knurls have also rolled over. So, the roller re-grinder will remove more steel from the knurl teeth to make sure the rollers look good. A roller with re-ground knurls may be as much as .015 to .020" undersize relative to its original (new) size and at best .010" less than the other rollers in the set.

In addition to grinding your rollers to less than OEM diameter, regrinding fails to take into account the differing amount of wear among the roller set. When you are ready to replace or recondition your rollers, take them out and lay all six or eight next to each other on a flat surface. You'll notice that three (or four) of the rollers are more worn than the other three (or four). This discrepancy in wear may not be given any thought in the regrinding process in which each roller is ground enough to remove any high or low spots. When the reground rollers are re-installed, you are likely to experience "gathering" when running, because the rollers are of different sizes. This is similar to running different size tires on one car, and results in reduced running speeds. A discrepancy of .010" between roller diameters among the set may not sound like much, but it amounts to a .03" difference in paper mis-feeding per revolution, or a real gathering problem resulting in lower run speeds.

The grinding of knurl steel also results in the eventual erasing of the teeth and loss of traction for driving the paper. In many cases there will be only a slight trace of knurl teeth in the center of the roller and the ends of the roller will show only smooth steel.

Let's summarize the situation.

  1. You've had your rollers reground and re-installed. They look good.
  2. But the rollers were ground to different sizes (the better rollers weren't ground as much as others) and this has caused a gathering problem.
  3. Some rollers were ground to the point where the knurl is practically gone. The ends of the rollers were ground more than in the middle.
  4. The glaze and hardness has been removed but the urethane diameter is less than it should be, the urethane has not been rejuvenated, and grip is not what it should be among all the rollers.
  5. Your rollers seemed to run faster at first, but before long they are actually running slower and slower, due to the lost traction of ground knurls.
  6. Before long, its time to get brand new rollers.

Regrinding has shortened the life of your rollers. Your sales rep knew that you would soon need new rollers and will be happy to sell them to you at 10-15% less than the OEM's prices. If for some reason you are still thinking of re-grinding your rollers to save money, ask your bindery supplier how long he will warranty the reground rollers.

Then consider asking us about our recovery and reknurling services. All MBO and Stahl rollers can be reknurled and recovered with new urethane, increasing grip and traction, and adding the maximum life possible, and saving you money in the long-term. FolderRollers.com/Wear Ever Mfg provides a one-year warranty on all recovered rollers.


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Folder Rollers | 2283 Camel Rd | Benicia, CA 94510
TEL: (707) 745-9199 | FAX: (707) 745-9166 | EMAIL: sales@folderrollers.com