These washing systems are designed for spray cleaning with aqueous detergents at a temperature of 60° C. Tunnel type washers may be single-stage and multistage with or without final drying according to the specific treatment requirements of the part. The moving system for the pieces can be made with different methods, usually it is made with a conveyor belt or mechanical auger. These machines are mainly identified according to the size of the conveyor belt or the auger and according to the washing treatment required. The machines can have one or more washing cycles, and different treatment stages are possible, for example, rinsing and drying.