„Technical cleanliness is no longer an option, it is an obligation“ stated Werner Renz, Solution Manager Technical Cleanliness, ZEISS Industrial Quality Solutions. And as contamination leads to machine down-time and reduces the working life of systems, the tolerance of solid particle contamination also reduces at an increased rate - not just in the automotive industry. Checks for particulate cleanliness in accordance with VDI part 19.1 or the international standard ISO 16232, has therefore become a fixed component of quality management.
Technical cleanliness is tested indirectly. Contamination is generally extracted from the interior of cases, pumps, valves or pipes. After the extraction of particles from the sample, the complete extraction medium is filtered and the particles deposited on an analysis filter.
The filter is examined under a light microscope to quantify the particle contamination. If a critical level of particles is found, analysis under an electron microscope often follows to define the elemental composition as a way of pinpointing the root cause of the contamination.
However, before the particles can be counted and classified, they must be removed from the component. HYDAC offers a number of different extraction devices for this task. Based on the requirements of the standard VDA Volume 19.1, as well as the company‘s own specifications, regulations for the analysis of the components are stored in the devices. For example, the volume flow of the test medium as well as the diameter and type of the nozzle with which the liquid is applied to the component are specified.
HYDAC extraction machines lead the user step by step through the entire process with software support. A process with which „We achieve the greatest possible amount of particle removal without attacking the material from which the component is made“ explained Thomas Schittek, Global Coordinator Technical Cleanliness at HYDAC International GmbH. This also ensures that the results are comparable across different operators.
ZEISS offers a number of customized solutions which can be seamlessly combined depending on the requirements. Reflective and non-reflective particles up to a size of 20 micrometers can be counted and classified with the ZEISS SteREO Discovery.V8 which is also capable of identifying fibers. The solution includes a microscope with a digital color camera and image analysis software customized to suit the requirements of the cleanliness testing. If the particles measure up to five micrometers, ZEISS offers the Axio Zoom.V16. And if particle definition has to extend beyond length and width to include height, according to Renz, the rig ht choice is the ZEISS Axio Imager 2.
With the ZEISS solutions users receive reliable, reproducible results regardless of the user who performs the analysis. Correlative particle analyses are also possible and easy with ZEISS. It takes no more than the push of a button to transfer the images of the particles detected with the light microscope to an electron microscope where they are analyzed. „Only with ZEISS instruments is this so easy“ stated Renz.
The determination of the material of which the particles are composed is added to information such as number, size distribution, morphology and color gained with the light microscope. Thanks to this in-depth information, more than the cleanliness of the components can be defined. Possible contamination sources, for instance, can be identified and therefore eliminated.
„With our software we are able to transfer these extraction parameters from the HYDAC systems automatically into the record of the microscopic analysis of the filters“ explained Renz. This will save not only time for the users as they wi ll no longer have to collect information from different systems. In particular, the operating errors of the analysis process will now be apparent earlier, „thus the security for the users is significantly increased,“ according to Schittek.
The collaboration between HYDAC and ZEISS was presented to the public for the first time in October 2019 at parts2clean, the leading international trade fair for industrial parts and surface cleaning. Both Schittek and Renz remember that reactions were completely favorable. They agree that „customers can be more efficient in their work if they are able to monitor their entire workflow.“ And the two of them are also certain that at present only ZEISS and HYDAC can provide this.