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AIM3D, based in Rostock (Germany), manufacturer of multi-material 3D printers, has developed a new generation of print heads for its proprietary CEM (composite extrusion modeling) process. The new extruder CEM-E2 is a multi-material print head for additive manufacturing that can print metals, plastics and ceramics. AIM3D is currently developing larger pellet 3D printers in order to be able to produce larger parts and achieve even higher build rates. The official market launch of these products is planned for Formnext 2021 in Frankfurt.
The new CEM-E2 extruder
The print heads of the CEM-E2 extruder are matched to different material groups. The print head of version “M” (metals) is used for metal-filled materials (MIM pellets), print head “P” (plastics) for filled and unfilled plastics and print head “C” (ceramic) for ceramic-filled materials with higher abrasion (CIM- Pellets). The new extruders / print heads are characterized by a significantly improved delivery accuracy. This enables a higher surface quality and better mechanical properties of the component. The extrusion speed has been increased by more than 200%, with production rates of up to 220 cm³ / h now being possible with a 0.4 mm nozzle. Clemens Lieberwirth, CTO at AIM3D: “The material feed as well as an optional water cooling and an improved holder for the quick change system are all new developments. The patented CEM-E2 extruder with its parameters tailored to specific materials sets new standards in CEM processes. “
The appeal of CEM technology lies in the use of an additive manufacturing system for multiple materials. In addition, filaments can often be dispensed with and conventional pellets can be used, which offers considerable cost savings. The greatest advantage, however, is the reduction in component assembly times through the direct use of pellets.
The 3D-printed PPS GF 40 manifold from Schaeffler
With the new CEM-E2 extruder, a component made of PPS GF 40 has been successfully developed for Schaeffler. A Celanese polyphenylene sulfide (PPS) was used. In addition to good basic properties such as high flame retardancy, this material offers a multitude of options for tailoring properties such as conductivity, thermal expansion or friction behavior. The development partnership between AIM3D and Schaeffler has set itself the task of developing a coolant distributor as a 3D-printed component. The extruder CEM-E2 was also able to print the identical PPS and, as with injection molding, the material PPS GF 40 was chosen for 3D printing. Normally, the alternative for 3D printing this component would have been a PA6 30 GF (polyamide), since glass fiber reinforced PPS in filament or powder form is not available for 3D printing. The PPS material enables higher temperature properties and improved mechanical properties as well as the potential for lightweight construction. The extremely high media resistance is also a decisive factor, as PPS hardly absorbs any water.
PPS GF 40 materials that are chemically identical to injection molding granulates are currently not available as filament forms for 3D printing. A cost-based comparison between the PPS filaments available on the market and the pellets already shows the great potential of pellet extrusion, even if the materials were available. Clemens Lieberwirth: “A direct comparison between PPS in filament and pellet form shows very clear cost advantages of the pellets as well as significantly higher build-up rates. The manufacturing costs for the component alone (machine hours + material) are around € 70, the printing time around 12 hours. Filament printers would need at least 50 hours with the same layer thickness (50 µm). ”According to Lieberwirth, PPS is an interesting material for many demanding environments in the automotive and chemical industries. For example in coolant distribution systems.
Versatile, stable, conductive and media-resistant
PPS offers a number of properties that other plastics, but also metals, cannot achieve. The lightweight construction material reduces weight and thus fuel consumption and CO2 emissions, and in many areas the customer can individually adapt material properties such as conductivity, tribology or stability to his needs. Combinations of these properties that other materials cannot offer are also possible. Compared to cheaper polymers, PPS has higher strength and lower thermal expansion. At the same time, PPS is more resistant to water, hydrolysis and solvents and offers clear advantages in terms of electrical and thermal insulation.
Another relevant advantage of PPS is its “built-in” flame retardancy. PPS is inherently flame retardant while other polymers require additives. However, some of these additives change the mechanical properties considerably and have the undesirable property that they can be washed out by steam or aggressive cleaning agents. In addition to flame retardancy, PPS has other advantageous properties without the need for further optimization. These include a high melting point of approx. 280 ° C, very low moisture absorption and very high chemical resistance – at room temperature PPS is insensitive to all solvents. Another advantage is its thermal and electrical conductivity. The use of additives and their dosage can increase the electrical conductivity, so that any specific volume resistance between 1 and 1015 ohms is possible. The functional properties thus range from antistatic, conductive properties and electromagnetic shielding to protection against electrical discharges. This makes the material suitable for industrial instruments in environments that require explosion protection or for electronics housings that have to meet electromagnetic compatibility requirements.