The quality feature "technical cleanliness" has developed into a performance requirement due to the development of ever smaller and more powerful parts, components and systems. Technical cleanliness (TecSa) can generally be defined as "the absence of critical contaminants", which can have a negative impact on the further production process or the function of the component or an assembly. Depending on the system, even contamination of a few 100 µm in size can lead to an increase in the susceptibility to wear and corrosion or to the failure of a complete technical system. Companies are increasingly responsible for manufacturing, assembling and distributing their parts, components and systems under increased TecSa requirements.

In addition to external customers, production processes within the value stream also define requirements for the TecSa of the component. If these requirements cannot be met by measures to avoid critical contamination and if the contamination tolerance of the customer process cannot be extended, a need arises to produce the functionally necessary cleanliness by cleaning. A wide variety of cleaning processes are available for the production of TecSa, which can be implemented in different combinations in a cleaning system. The majority of these cleaning processes can be classified as non-conventional processes, which are based on chemical and/or physical active principles and require specific plant technology and infrastructure. This raises the question of how to integrate these processes into the production layout efficiently and in line with requirements. Since the production layout usually comprises several value streams, the question arises as to when the ideal of segmenting the value streams should be abandoned in order to maximise the degree of fulfilment of corporate targets through the use of economies of scale in the cleaning sector.

However, it is not only the state of cleanliness of the component at the end of the cleaning process that is decisive, but also the state at the point of further processing or use. As soon as the components leave the cleaning system, they can be re-contaminated by various product-, process- and resource-induced factors. The TecSa of a component is thus a fragile state that must be created in a process-safe manner and maintained along the value stream.

The spatial organisation of cleaning systems contributes decisively to the generation and maintenance of the TecSa and influences the achievement of the operator's business targets in the area of conflict between costs, time, quality, flexibility and stability. As no specification and operationalisation of relevant characteristics and interactions for this planning task have been carried out so far, it is currently not possible to carry out a quantitative evaluation of cleaning concepts. In addition, it has become apparent that the strong influence of the organisation of the cleaning system on the performance of the entire production requires a cross-value stream consideration that encompasses several interdependent and influencing fields of consideration. These fields of consideration include the identification and characterisation of cleanliness gaps (cleaning cases), the selection of cleaning processes and systems, the evaluation of material flows and the spatial form of organisation, and are to be investigated and interlinked in the present research project (Figure).

The connection of these fields of consideration forms the cross-value stream component cleaning concept focused on in the project. This holistic approach and an analytical overall system make it possible to design different component cleaning concepts, evaluate them quantitatively and select them in such a way that the target values and requirements of the operator are optimally fulfilled.

Particularly in mechanical engineering and in the electronics industry, component cleaning is an essential manufacturing process to ensure product quality. Both industries differ fundamentally in the type of production and the production principle. Whereas mechanical engineering is generally organised according to the fixture principle, electronics manufacturing is predominantly carried out according to the object-oriented manufacturing principle. For both organisational forms, it is necessary to develop an approach in order to deal economically with increasing demands on TecSa, to produce them efficiently and to maintain them.

In order to make the complex planning and decision-making process manageable, the research project aims to design a holistic system that can be used to analyse cleanliness-critical value streams and to design and evaluate the integration and organisation of cleaning systems. The result of the research project consists of three main aspects:

Creation of an analysis methodology for cleanliness-critical value streams for the systematic identification of cleanliness gaps along the value stream as well as the characterisation in the form of cleaning cases.
Conception of a logic for the evaluation of component cleaning concepts, which evaluates the offered processes and their allocation to cleaning cases in different value streams with regard to factors such as total costs over runtime, throughput time, risk of back contamination along the material flows, etc.
Establishment of an eBusiness platform on which cleaning cases and offers for cleaning concepts can be exchanged and evaluated.

Based on a requirements analysis, singular procedures are first developed for the areas under consideration. These form the basis for the subsequently developed overall system for the quantitative planning and evaluation of cleaning concepts across value streams.

The IGF project (19110) of the research association Gesellschaft für Verkehrsbetriebswirtschaft und Logistik e.V. - GVB, Wiesenweg 2, 93352 Rohr is funded by the Federal Ministry of Economics and Technology via the German Federation of Industrial Research Associations within the framework of the programme for the promotion of joint industrial research and development on the basis of a resolution of the German Bundestag.

• Federal Ministry of Economics and Technology 
• Federation of Industrial Research Associations "Otto von Guericke" e.V.
• Society for Transport Economics and Logistics e.V.