The 3D printing process is becoming increasingly important for glass and ceramics and now complements conventional, mould-based casting processes or even milling. Since 2021, FGK (Forschungsinstitut für Glas/Keramik) in Hoehr-Grenzhausen has been using a 3D CEM system ExAM 255 from AIM3D for research purposes. The 3D process offers major advantages with respect to time and costs when it comes to evaluating ceramic test specimens. It also enables more material combinations than standard manufacturing strategies. The focus lies on technical ceramics, but also on medical applications.
Accelerating research by using 3D rapid prototyping
The CEM process, as an approach to 3D printing, is the addition to the conventional CIM process (ceramic injection moulding). The tool-free construction of components saves a considerable amount of time and significantly reduces costs. Having already proven this for prototyping, it is also particularly important in the production of test specimens for material testing – new ceramic materials can thus be evaluated more quickly. New compositions of ceramic granulates can also be developed faster. Furthermore, the CEM technology allows FGK to be independent of the industry as no moulds and capacities for test specimens need to be acquired. FGK is thus self-sufficient through 3D printing.
Hybrid components: Ceramic multi-component technology
Project engineer Murat Demirtas: “The real charm of this CEM process from AIM3D is its flexibility. The ExAM 255 multi-material printer allows combinations of ceramic/ceramic, ceramic/polymers or ceramic/metal. Hybrid components massively expand the component properties, enabling a functional design.” Specifically, this means that a combination of different ceramics, or a combination of other material classes, can be used in a single component in order to reproduce certain properties in a component. It is also possible to create parts by starting with a voluminous base produced via the CIM process and then adding a smaller printed component using the CEM process. The combination of ceramics for electrical insulation and metal for conductivity is also interesting. This allows for MID (Multi Integrated Devices) approaches. Obviously, the performance characteristics of a component can also be increased. Possible parameters are variable grain sizes, certain surface characteristics, but also certain chemical (media resistance), electrical (conductivity factor) or thermal (temperature resistance) properties. 3D printing using the CEM process opens up a variety of possibilities thanks to hybrid material and hybrid manufacturing solutions.
3D design of a ceramic component via FEA
The design of a 3D component is already part of the digital process chain. The original geometry of a 3D component is optimised in an iterative process using finite element analysis (FEA) and successively simulating the stress zones within the component. Furthermore, taking into account the shrinkage of the ceramic due to thermal process control results in additional adaptations of the 3D component. The topology is particularly important, as it is possible to use lattice structures that save weight while still ensuring the required strength. Murat Demirtas: “The tools of finite element analysis make it possible to design a component in such a manner that it specifically fits to the desired application. For this, aspects of bionics, topology, material savings and performance characteristics are combined.”
Advantages of 3D printing for technical ceramics
AIM3D’s CEM process uses conventional granulates or powders which are highly cost-efficient compared to filaments. For the feedstock, the total costs can be reduced by up to a factor of 10. In addition, bionic structures with different densities are possible and the reduction of stresses in the component also opens up advantages compared to a conventional CIM process. The parts can now be lighter and require the use of less material. The reduced resource consumption, compared to milling or casting, is a clear advantage of a 3D printing strategy. Furthermore, 3D printing makes geometries possible that cannot be realised with conventional manufacturing processes, such as special undercuts or bionic designs. Another significant advantage is the “one-shot technology”: a component is built up successively without any need for assembly, even when certain functionalities are integrated. A conventional component can thus be constructively and functionally optimised with 3D printing through reengineering. The research conducted at FGK naturally covers a wide range of topics: from materials research, over topology optimisation with the aim of reducing stresses in the component to functional enhancement and integration, as well as the tailoring of surface quality (porosity).
Users of ceramic components
Ceramic components play a major role in medical implants due to their biocompatibility in combination with strength. In this regard, open-porous structures are particularly suitable for absorption in the tissue. Selective densities save material and weight and produce the desired Young’s moduli. The core application field, however, is technical ceramics. Depending on the application, a ceramic solution can have the following characteristics: heat resistance to well over 1000 °C, electrical insulation, high dielectric constants, high abrasion and wear resistance, variable degrees of hardness, variable thermal conductivity, low density or even low thermal expansion, to name just a few keywords of this versatile material. Areas of application are, for example, heating elements, spark plugs, high-voltage elements, electronic circuits, ceramic capacitors with high volume capacity, sliding surfaces, nozzles for laser and water jet cutting (cutting nozzles), sliding bearings in pumps, pistons and cylinders, powder-coated metal surfaces, ball bearings, use as cutting material (cutting ceramics), in machining, coating of pumps in the chemical industry, as well as the implants mentioned in medical technology. Besides this, non-technical ceramics are obviously also important, for example, in the areas of utility ceramics (including porcelain), tiles or sanitary objects, but these are of little importance in the area of 3D printing due to the large size of the components or large batch sizes.
Research at FGK
The FGK institute conducts material analyses using various process technologies, including the CEM process, but also deals with granulate developments, such as new “formulations”. The aim is to further develop the performance of ceramics. This is complemented by the search for new areas of application for ceramic and hybrid 3D component solutions. The institute also offers material services on behalf of industrial companies, and consulting services along the process chain. FGK is thus a facilitator between the producers of raw materials, machine manufacturers and the processing industry.
The article originally appeared on the website of FGK Research
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