Screen print dryer belts made from PTFE coated fiberglass mesh operate in extreme temperatures and offer release characteristics that few other materials can match…but they are not inexpensive, and care should be taken to get the maximum life from these belts.
Here are a few tips to help make your belt last a little
- Take a moment to be sure when ordering a new belt that you get the dimensions right. These belts are nearly impossible to modify in the field given the extreme heat and pressure required to seal edges and reinforce the “bullnose” for the alligator lacing (or other splice type). If your mesh dryer belt is too long, it will have to come back to the factory to be shortened… if it’s too short, we will have to make a “dutchman splice” that will lengthen the belt, but you will now have 2 splices in your belt and tracking issues may result.
- Take time to install a new PTFE coated fiberglass mesh dryer belt correctly. Here’s a link on how to do it right. Be sure you get it started right and you will have better shot at a long belt life.
- Load the belt carefully. Most screen print dryer ovens do not have automatic tracking systems installed. They typically run slow and can often run for years with no adjustments if installed properly (#2 above). In order to give your belt a good chance of tracking properly be sure to load it evenly. You can load the center of the belt or alternate left and right as the dryer runs. Avoid heavier products placed only on one side of the belt, as this can pull the belt out of square and distort the weave.
- Avoid crowned pulleys. Crowned pulleys are sometimes used in belting applications, but with a Teflon coated fiberglass mesh belt, anything but the slightest of crown in the pulley can actually split the belt in two. Remember that these are made with PTFE coated fiberglass yarns and, like anything fiberglass (imagine a fishing rod) if you repeatedly bend it over a sharp radius, you will wear it down, and possibly break it at that point. A mesh dryer belt is constantly flexing as it travels over pulleys and deflects slightly under the load it is carrying. If you have your heart set on installing a crowned pulley, check with us first to see how much of a crown you can safely put in place (hint: It isn’t much!).
- Do not over-tension the belt. If slippage occurs, the first thing to do is to clean your drive pulley. There should be enough friction as delivered by the factory to drive the belt without over-tensioning it. These belts are made with a woven PTFE coated fiberglass yarn and are not intended to be tensioned like a V-belt on your car! You can easily pull the splice out of the end of the belt, tear the alligator lacing at the corners or distort the belt to the point where it does not track properly (you could also take the dryer out of square, causing tracking issues). If you need additional friction in order to keep the belt moving, contact us and we’ll let you know what we think is the best way to get it moving. It involves applying a “lagging” tape to the drive roll, but you must do it right!
- Support heavy loads with a slider bed underneath the belt. Of course, if you purchased your dryer with printing glass panels in mind, you no doubt already have a support bed of either flat panel (stainless steel) or rollers to hold all that weight. If you are retrofitting your dryer, be sure to consult the dryer manufacturer before making significant modifications but do support the load properly one way or another because these belts are not intended to support heavy loads in free-air under tension.
- Do not stop your belt under a hot lamp. If you’re using an infrared curing dryer (electric or gas fired) be sure that the belt does not stop under a lamp that is hot. High temperature heat sources can destroy the PTFE coated fiberglass substrate, effectively “burning a hole” in the belt. If this does happen, this is one of the few repairs you can make in the field. Contact us for a repair kit that will include materials needed to make basic repairs.
- Take care not to let a cart, box or other item contact your mesh dryer belt while it is running. We’ve seen a number of belts split in two when a cart or a box was allowed to rub against the belt for an extended period of time. A short tear can sometimes be patched in the field, but long tears often ruin the belt, as there is no good, cost effective way to bond it back together.
- Finally, do not cut your belt off the machine in order to measure it. Use our simple guide to measure it properly. This seems obvious, but we’ve seen that happen and it can be wasteful. In many cases, we’ve made new dryer belts for customers who then send us their old belt that is still in reasonable shape and we’ll give it a “tune-up” that allows it to be used as a spare, backup belt.
We’ve been manufacturing PTFE coated fiberglass fabrics, tapes and belts since 1991 and are ready to help in any way we can. Just “zing us a note!”.