CONSIDERATIONS WHEN SELECTING CORROSION RESISTANT AND WASHDOWN CONVEYORS
Conveyors intended for food processing, pharmaceutical, wet product, or clean room applications should be given careful consideration. Conveyors utilizing bearings, which are re-lubricated, can cause purged lubricant contamination of both the belt and product. Bearings, which are sealed for life, can eliminate lubricant contamination. These bearings should be of stainless steel construction when moisture is present. Bearings should also incorporate a shield or slinger plate, which covers the seal. This is also helpful in keeping water from impinging on the seal in wash down applications. Belting using a woven carcass can release fibers from exposed raw edges or from a worn belt bottom. Conveyors utilizing knurled pulleys should be avoided, knurling can cause accelerated fragmentation of belt fibers. Moisture in belt carcass can also breed bacteria. Belting comprised of a suitable solid structure such as urethane, can avoid most belt problems. If a woven carcass type belt is to be used, it is recommended that edges be capped with a thin layer of urethane to cover exposed edge fibers. Underside of belting should have a urethane impregnation to retard absorption, and release of worn belt fibers.
Wet products or periodic wet cleaning can cause rusting and corrosion to any unprotected surfaces. In general stainless steel is preferred for most structural components. Suitable plating such as electroless nickel can be used on non-wearing surfaces but should be avoided on pulleys, bearing plates subject to belt contact, or on bearing wear surfaces. Belting can rapidly abrade plating exposing base metal to corrosion. Areas, which tend to collect moisture or contamination, should be eliminated where possible. Ease of cleaning should be given major consideration to avoid excessive down time and permit complete cleaning. Direct coupled drives are preferred to those using chain, or belting to avoid lubrication and fine dust caused by high-speed belt wear. Motors and reducers should be compatible with environmental conditions.