According to VDA 19.2, the cleanliness specification of a component, an assembly or of the assembled system is the starting point for assembly cleanliness during production. The goal is long-term avoidance of the entry of particles during assembly and its adjacent processes, which according to the cleanliness specification must not occur in the component.
However, from a technical and economical perspective, it is rarely possible to completely prevent the emergence and spread of these function-critical particles during complete assembly, its environment and in all logistics processes. Rather, it must be ensured that these cannot reach the cleanliness-critical functional surfaces of the components or assemblies. To meet the large range of cleanliness requirements - especially considering the environmental factor - the VDA 19.2 classifies the spatial environment into "clean areas" with different levels of cleanliness for the design and organization of the assembly area.
In addition to the influencing factor from the environment, the influences of personnel, logistics and packaging, as well as the influences from the processes themselves and of the assembly facilities must be taken into account.