Magytec supplies both belt presses and filter belts for belt presses. As a machine supplier, we have an intimate knowledge of the stresses and strains, as well as the wear loads, imposed on filter belts. We are also able to select the best combination of mechanical and process performance for your application. The belts we supply are sourced world wide by leading manufacturers.
A well designed and selected belt press such as the Magytec/SernaGiotto units, applies the minimum stresses on a filter belt, however we still believe in providing the highest quality belt in order to ensure maximum availability and reliability.
Lower cost belt presses as sometimes supplied by our opposition, can have compromise drive, tracking and tensioning systems, as well as excessive deflection rolls and frames. This results in much higher loads on the filter belts, but a high quality belt can sometimes partially compensate for a poor machine design.
FACTORS IN CHOOSING A BELT
The open area and weave required to support the cake, and at the same time provide sufficient water drainage and ease of washing.
Cloth material to suit the chemical and abrasion conditions.
Sufficient strength to handle the belt tension.
Sufficient cross machine (CMD) strength to prevent creasing.
A seam to match the operating criteria.
Price is a misleading factor- a low cost filter belt can compromise the operation of the press, leading to higher operating costs and poor process performance!
A good belt life depends on many factors, but in general, a well selected belt on a light duty application can last from 1500 to 4000 operating hours. Life can also be influenced by operator attention and the state of the press. Beyond the 2000 hour mark, the risk of accidents also becomes significant. For more arduous applications, typical life is 1000 to 3000 hours.
The lowest cost seam is a metal clipper type. This kind of seam is deceptive in appearance. It may look strong, being made from stainless steel, however it suffers from two weaknesses-inflexibility and the fact that it is hooked into the parent cloth rather than woven. The joining pin can also be critical- a flexible belt needs a flexible pin, but too much flexing will lead to seam failure.
Metal clipper seams are suitable for low stress applications in soft, non-abrasive materials and on well designed belt presses. A strong belt can also help protect a metal clipper from excessive distortion.
When operating in conditions where high stresses are applied to the belt for whatever reason, a plastic seam will provide the longer life. The advantage of the plastic seam is that it can move with the parent belt material, and that the loops forming the joint are woven by hand into the ends of the belt, providing a spliced type joint. This skilled and time consuming process is obviously more expensive than a simple clipper seam.
A variety of different plastic seams are available, including a simple pin type (the V. Seam) and the easier to close woven-in spiral, the U. Seam.
The most popular weave type in our range is the 2/1 twill type such as the R013, which has many applications. This belt provides good cake support, but also high drainage through the diagonal apertures in the weave. In addition, the large plastic wires provide good strength in both directions, making it resistant to creasing, and providing a long abrasion life.
Many other weave patterns and wire sizes are available to suit different applications.
Weave selection is always a compromise- a tight weave will support the cake well and provide good cake release. An open weave will provide higher drainage rate and will be easier to wash. More open weave belts are also usually made from heavier wires, and hence are stronger.
A typical 2/1Twill weave
The two main materials used for belt press filter cloths are polyester and Polyamide (nylon). Polyester is a good all-round material, and is the stiffest and most stable dimensionally. Polyamide is more flexible, has a higher abrasion resistance, and is suitable for high pH applications. Special belts are made from combinations of both materials.