Over the years, I have read many articles about how to reduce screen blinding on vibratory screeners. These solutions range from polyurethane balls to brushes. One of the most frequent questions I get asked is how to clean screens once they are blinded for fine mesh applications. Some customers simply throw out the blinded screens or send them back to our rescreening department for a fresh, new screen to be applied.
A screen does not necessarily have to be a very fine mesh in order to blind. We have seen screens with a mesh as coarse as a 2 or 3 mesh can easily blind due to product lodging in the openings while conveying across a screen deck. Of course, the larger the mesh opening the easier the screen is to clean. A fairly larger opening can simply be cleaned from the “bottom-side” of the screen surface with a simple soft wire or hard nylon brush. We have touched on this type of screen deblinding in previous blogs, you can click here to read more about solutions we suggest for these types of screening applications.
On finer wire mesh screens, let’s say 200 mesh and finer, a soft bristle brush may work but you risk tearing the screen surface, or worse yet, cutting a couple of very fine wire mesh thus turning the 200 mesh opening into a much larger sized opening! If your screen frames are small (3”, 8”, 10”, 12”), like the one pictured to the left, there are very nice and reasonably priced ultrasonic baths that are very effective in cleaning the hardest material from the mesh apertures. Another, more cost-effective method is pressure washing the screen surface. This is done by pressure washing from the bottom side of the screen surface. Essentially forcing the dislodged material back out of the screen apertures. From our experience, don’t place the pressure washer tip too close to the screen surface. Trust me, you will easily blow a hole through your screen!
It’s important to state, some material may melt to your screen surface if the surface gets too hot or there is too much material build-up on the screen surface. If this is the case, such as with powder coatings or some nylon materials, we will use solvents to easily clean this type of material from the screen surface. Simply submerge the screen in a bath of solvent and give the solvent some time to dissolve or soften the material. Then there are some of the extremely stubborn or impossible-to-remove materials like ones that tend to be jagged type materials such as hammer milled materials. Unfortunately, for some materials, there is no hope of cleaning the screen.
Once a screen has been cleaned numerous times, inspect the screen for sagging or any small holes or tears. If any of these are observed we suggest either purchasing a new screen frame or getting them rescreened. In some cases, a new screen may be necessary but if the frame is in good condition, rescreening your old frame will save you 30-40% of an entirely new screen frame.