The washing tunnel system is the most traditionally known and common system in the industrial washing industry. The parts are placed on a conveyor and then driven through a tunnel passing under jets of water enriched with specific chemicals until they reach the drying oven after which they are conveyed to the exit. The linear layout makes this solution ideal for processing lines with an in-line linear layout. Depending on the factory logistics and type of washing, different types of conveyor can be used: conveyor belt, overhead conveyor, bound pallet chain conveyor, free roller.