The main application of additive manufacturing with plastics and metals are individualized components in small quantities. Here, the size of individual components are often technologically limited by machine size and economically limited by manufacturing times. 3D printing with pellets using screw extruders, known as SEAM (Screw Extrusion Additive Manufacturing) or FGF (Fused Granulate Fabrication) enables orders of magnitude higher material throughputs compared to other processes such as Fused Filament Fabrication (FFF). In addition, the output is scalable over a wide range due to the extruder size. With weight-optimized extruders that can be flexibly used with the help of industrial robots, material throughputs of up to 5 kg/h can be achieved. With larger extruders that are used in gantry systems, for example, throughputs can easily be increased tenfold. High discharge rates and large installation spaces through the use of robotics and linear systems thus make the production of large-format components possible.
The BMW Group is making impressive use of the possibilities of direct extrusion of pellets in additive manufacturing for the production of production tools. One application field with particular potential are handling systems. An additive manufactured gripper system is used, for example, in the series production of CFRP roofs. The bifunctional gripper handles both the depositing and positioning of the dry preform and the removal of the component from the RTM (resin transfer molding) process, in which the carbon fibers are impregnated with resin in a molding tool and cured to form a component. The printed load-bearing components consisting of a shell structure, an A-shaped beam and two cross beams have a total weight of approx. 80 kg.
The construction times of the individual parts are between 3 and 9 hours for wall thicknesses of up to 5 mm. The plastic multi-gripper replaces the conventional gripper solution, which is divided into two effectors depending on the function, and thus reduces the total weight of the production aids used. The efficiency of production is additionally increased by a reduced cycle time and the elimination of deposit stations. A key advantage of the process is flexibility. 3D printing from granules makes it possible to break completely new ground in fixture construction. The fixtures can be quickly modified and adapted on site to meet changing requirements in a timely manner. This saves engineering costs and slims down the production process enormously.
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Plant technology for direct extrusion of granules for additive manufacturing of large-format gripper systems, consisting of a shell structure and a support structure with two additional cross beams
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Multigripper with additively manufactured load-bearing components made of carbon fiber-reinforced polyamide in series production of CFRP roof shells.
With the appropriate materials, the technology makes it possible to implement applications in plastic that were previously manufactured in metal. Carbon fibre reinforced thermoplastics are very well suited for lightweight construction of structural applications in additive manufacturing due to their high stiffness and strength combined with low density. Dimensional stability during processing is crucial here, especially when the size of the molded part increases. Highly reinforced materials offer a clear advantage here due to low shrinkage.
A build room temperature control is not required for the processing of these materials, for example AKROMID® B3 ICF 40 AM black (8236), so that large-format structures can be produced without complex plant engineering. Direct extrusion of large-format, load-bearing components in combination with other plastic-based additive manufacturing processes has reduced the weight of the component gripper by more than 25 % compared to a conventional solution, and even cut provisioning times by more than half. BMW has recognized the potential of the process and sees great potential for further areas of application.
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In additive manufacturing, the BMW Group uses compounds from AKRO-PLASTIC, which are reinforced with processed post-industrial carbon fibers (PIR). Together with the weight reduction of the gripper system, the reduction of the energy input and the use of sustainable material solutions, this process is another small building block towards even more resource efficiency in the production of the Munich car manufacturer.
AKRO-PLASTIC develops application-specific plastic compounds. We support our customers in application development for 3D printing.
Disclaimer: All specifications and information given on this website are based on our current knowledge and experience. A legally binding promise of certain characteristics or suitability for a concrete individual case cannot be derived from this information. The information supplied here is not intended to release processors and users from the responsibility of carrying out their own tests and inspections in each concrete individual case. AKRO®, AKROMID®, AKROLEN®, AKROLOY®, AKROTEK®, ICX® and PRECITE® are registered trademarks of the Feddersen Group.