Quality and technical cleanliness

According to DIN 8592, cleaning means removing unwanted substances (contaminants) from workpieces' surface to a required, agreed, or possible degree. The end-use or the subsequent process thereby determines the technical cleanliness.

To clean components, Fraunhofer IGCV uses various processes depending on the cleanliness requirements. Numerous in-house cleaning systems are used, such as an ultrasonic cleaning system, blasting system, CO2 snow blasting system, low-pressure plasma cleaning, or brush wash tables. However, if we need a system that is not available in our inventory, we can fall back on a large partner network. This enables us to design application-specific solutions.

Production-related contamination is thus efficiently minimized to be able to carry out a successful subsequent process. Examples of such contamination are oil residues that impair the subsequent welding process or oil-grease residues that affect the subsequent painting process.

The ULTRAREIN project serves as an example of general component cleaning.

In additive manufacturing, we mainly deal with the processes of laser beam melting (Laser Powder Bed Fusion, L-PBF for short) and cold gas spraying (DED process). Only metals and no plastics are used as materials. Also, we deal intensively with multi-material processing.

The big challenge here is that the material also represents the contamination. In additive manufacturing, the material particles fuse with the surface. Conceivably, not all particles have (completely) bonded with the workpiece at the end of the manufacturing process. These can become detached and thus represent contamination in the further production steps. Another challenge is the design of most components. Many are very complex in design so that the cleaning mechanisms cannot reach all surfaces within the workpiece. Current cleaning technologies already reach their limits here.

Therefore, our goal is to use our research to analyze these structures to develop optimal cleaning processes. To do this, we develop analysis methods that check whether the desired cleaning condition has been achieved. This ensures that the powder material does not later endanger its use, cause damage to the component, or even pose health risks to employees and customers. Also, resources are conserved, money is saved, and rejects are reduced.  

We also use technologies from non-destructive testing to monitor the quality of the component during the process. This makes it possible to directly detect defective components and remove them from the process at an early stage.

In battery production, we deal with various cleaning processes and the quality inspection of lithium-ion battery cells. In doing so, we examine electrode surfaces and the battery separators.

Particulate contamination on the electrode surface of lithium-ion battery cells can be detected by active thermography. Manufacturing-related contaminations must be removed from the battery separators in a targeted, efficient, and damage-free manner. Different optical test methods do the detection of the contaminations. These methods are constantly evaluated and further developed to ensure quality in battery production.

Information on Research Fab Battery Cells

Connection technology describes the constructive methods of assembling technical structures from their individual parts. Connections can be detachable, non-detachable, or conditionally detachable. Joining techniques can be classified according to physical principles: form-fit, force-fit, and material-fit.

Our work here is particularly on the preparation of various surfaces for soldering, welding, and bonding. The surfaces must be free of contamination, such as from oils and greases. Otherwise, the weld seams may not form properly, or the adhesive may not work properly. As a result, further processing may not be able to be carried out successfully.

The term surface technology generally refers to all technologies that can change surface properties. In this case, the surface of the components must be adapted according to the downstream process.

Depending on the requirements profile, the surface can also fulfill many other functions. For example, good corrosion resistance, wettability, or paintability are important.

Remanufacturing is the industrial process of refurbishing used products. Solutions are developed, for example, to supply motor vehicles and commercial vehicles with spare parts of the highest defined degree of cleanliness and original function in a cost-effective and resource-saving manner. The product performance made available in this way is intended to be equivalent to that of equivalent new production.

Despite the many established fields of application, there is potential to optimize costs and quality in remanufacturing. This is often caused by the smallest impurities, impairing product quality and even leading to system failures. An example of this is engine damage resulting from insufficient technical cleanliness of a cylinder head. Examples and analyses show that the remanufacturing of old parts can save up to 80 percent of manufacturing costs in individual cases and reduce material consumption by almost 90 percent.

Typical product segments for remanufacturing are mechanical, mechatronic, and electronic automotive and truck parts or assemblies, such as starters, alternators, engines, transmissions, and brake calipers.

Our ASPIRE project provides further information on the design of cleaning process chains in remanufacturing.