Dear Engineering Colleagues
I'm stuck with an eerie problem, with no solution whatsoever: As a start: I'm in front of a conveyor with a white belt (glossy white, Polyester fiber core with Polyurethane coating). The belt is moved with a drum motor and redirected several times around return shafts (1.4301 stainless steel) that are held with sealed ball bearings. The belt runs atop a sheet metal on the upper side of the system. That's it. The problem: After only days of use, the under side of the white belt turns black. The upper side that has seemingly no contact with anything but the drum motor: It's black. The return shafts have large areas that are covered with a substance that seems like molten plastic/resin, however, inspection with a thermal camera yields no higher temperatures than room temperature anywhere. Additionally it looks almost tempered black. The sheet metal: It's black and has those stains looking like molten plastic/resin as well. Everything is accompanied with a powdery pitch black substance in inexplicable quantities (mass conservation does not seem to exist here haha). This thing is proven to to run over years (motor is sealed and has no leakage) , but becomes dirty in almost sterile environments very fast. Suppliers of the belt and motor have confirmed a correct construction of the set-up, forces are well below what would be allowed for all parts. Everyone is baffled. I'm suspecting the belt to have a problem, but I have no idea how a white PU belt would become stained pitch black under contact with only steel parts?!
I hope anyone that one of you has encountered a similar problem over the years, as I'm really perplexed from what I'm witnessing here.
Kind regards, harry