Washing machines with rotary drums are ideal for the bulk washing of small and medium sized parts. They are ideal for utilisation in turning, threading, stamping and deep drawing processes. The parts are loaded in bulk manually or through automatic feeder systems such as conveyors, vibrating hoppers or box tippers. The principle behind the process is very simple, the rotating drum is made of a cylinder constructed of sheets either perforated or unperforated, within which a spiral is formed, also in sheet metal. Its rotation pushes and leads the parts loaded from one side, along all the processing stages up to them being offloaded at the opposite side. The slow rotation of the rotating cylinder carrier enables the material to advance, which is slowly stirred and undergoes the intended treatment cycle. In wet treatment zones, the pumps draw the solution from the respective tanks and feed it through special sprayers collectors inside the rotating cylinder onto the parts. After having covered and soaked the pieces, the solution falls into the tank through the drainage holes in the rotating cylinder carrier. A basket filter retains the chips or other impurities detached from the parts in each section. Large areas for drip drying the parts prevent liquid from being transferred from one zone to another. The drying is performed by a current of hot air, which once heated by the electric resistors or by the heat exchanger, is recirculated continuously by an electric fan. At the offloading point, a specially designed chute directs the parts to the collection container.
Rotary tumbler machines are used for small parts (in particular screws) where it is necessary to remove phosphates, films or Bonderite, before moving on to the following phase for further processing; a typical application is tumbling of "rivet, screw not yet threaded" before rolling. They can be used to successfully remove light burrs or sharp edges and obtain a surface polishing. These machines are made up of an octagonal truncated pyramid shaped tumbler which is loaded with a defined volume of parts to be treated; the tumbler is then rotated with multiple programmed speed "adjustable by inverter"; rotating clockwise the material is continuously and vigorously stirred while a pump injects the washing solution; depending on the set time, it is possible to obtain simple washing results, or, due to the effect of parts rubbing together, a reprocessing of the burrs and a polishing of the surfaces. After the wash phase, it is possible to continue in the same way with the rinsing phase followed by the drying phase with hot air. At the end of the treatment, the rotation direction of the tumbler is reversed and a special spoon shaped device allows the emptying and therefore the offloading of the parts. If greater volume is required, the machine can have two adjacent tumblers, in this case, the first tumbler performs the washing and rinsing phases, while the second performs the drying phase. The basic models are designed for loads with a volume of 100 or 200 dm2, on average equal to 400 or 800 kg. The machines can be equipped with automatic loading systems with lift/box tipper.