Drying machines and lines for web products, parts for the aforementioned machines, particularly recirculated air driers, inert gas driers, infrared driers, tempering machines and lines for web products, parts for the aforementioned lines, particularly calendars, low-pressure presses, high-pressure presses, double-belt presses, embossing and laminating machines for the production of hot and cold laminates, floor coverings, parts for the aforementioned machines and lines composed thereof; Self-lubricating mechanical friction parts, especially of composite materials, namely, wear rings, washers, bushings, spherical bearings, bearing pads, sliding blocks and machine transmission gears all for load bearing machines, conveyors, handling trucks and machines, lifting machines, agricultural machinery, construction equipment machines and hydraulic turbines