Ceramic ink codes automotive parts at high temperatures
A heat-resistant, ceramic-based ink could mean metal automotive components that are manufactured at temperatures over 1,000°C can finally be marked with a code carrying detailed information about process parameters.
The code can be scanned and linked to a database. According to the developers at the Fraunhofer Institute for Ceramic Technologies and Systems (IKTS), in Dresden, Germany, this allows detection of production glitches and defective components at an early stage, but also offers wide-ranging possibilities for designing process chains more efficiently and preventing component forgeries. Previously, imprinted codes were destroyed when heated.
Senodis Technologies, who is responsible for the software and ccommercialisation of the research, explains how the work is the result of a 2013-14 R&D contract between Volkswagen and Fraunhofer IKTS for the development of a heat-resistant ink.
The new Ceracode ink consists of heat-resistant ceramic particles and a glass component, but the developers cannot divulge further proprietary materials information. In the oven, the melting glass ensures that the marking is fixed to the metal and yet is still easy to read.
'Inks used in the metal sector…are based on ceramic pigments for both adhesion to the components and contrast generation,' shares Professor Thomas Härtling, whose team led the work at Fraunhofer.
To make Ceracode, Senodis says, 'These particles are first prepared so that they can be printed as inks in common industrial printing processes. Important processes [include] grinding to achieve the correct particle sizes and the production of an ink dispersion in which particles are stabilised with dispersants.
'This ink dispersion forms the basis for the actual ink production, to which, in addition to solvents and binders, other additives are added to stabilise the particles in the solution and prevent settling. Further additives are used to produce a good print image even on contaminated surfaces or oily materials, [and] each ink has a different composition of ingredients. Particles, additives or solvents may be adapted for other materials.'
To achieve heat resistance, Senodis says, 'The Ceracode ink for hot forming consists of a core of ceramic particles that remain stable up to approximately 1,200°C. The combination of adhesion promoter and contrasting pigment then ensures a robust and permanent marking even after high-temperature steps'.
Furthermore, 'for other materials, such as ceramics, other particles can be used...In this way, temperature strengths can also be generated well above 1,600°C'.
The key features of the ink are reported as resistance to oiling, the aforementioned high-temperature resistance reaching over 1,600°C, material-locking connection with component surface – light, dark and UV contrasts – precise print images and robust printing technology for industrial use.
For protection against forgeries, they can 'add special pigments to the formula of the ceramic-based inks so that they are illuminated in a defined colour under UV light', explains Härtling.
The combination of Ceracode ink and a standardised data matrix code means, 'the quality of every component or workpiece can be recorded along the value chain at any time, and defects can be identified right at the start of production and rectified in a targeted manner. This doesn’t just save companies energy – it also means they aren’t wasting raw materials and are able to reduce their carbon emissions', says Härtling.
The developers also believe the process data stored in the database makes it easier to set up adaptive process chains.
Senodis says, 'The hardware costs are about 25-30% of a commercial laser marking.
'The installation of the Ceracode marking system can take place within one maintenance shift. Use of standardised integration components, both on hardware and software side, and a modular design enable an easy implementation.'
The Fraunhofer researchers are now working on how to imprint curved or shaped metal components.