Large-scale printing
Assembly Line
BMW goes bionic: A closer look at BMW's 3D printed robot grippers
Laura Griffiths speaks to Jens Ertel (JE), Head of BMW Additive Manufacturing, and Markus Lehmann (ML), Head of Installations Technique, Robotics, about BMW’s design and deployment of customised 3D printed robot grippers.
For the topology optimisation we first needed a so-called design space. This is the region or volume within which the optimisation algorithm is allowed to distribute material in order to find the optimal structural design. The design space represents the available physical space or domain where the structure can be placed. Additionally, the non- design spaces are defined. These are mostly mounting plates that are needed to later fasten add-on parts and to attach the gripper to the robot and that will be integrated in the bionic structure during the optimisation. After that, the forces and torsional moments acting on the gripper are estimated and the allowed deformation is defined. Also, the material properties and a minimum strut thickness are set. With all these values and some additional details the topology optimisation can be started. Through the clever combination of two different optimisation approaches, the resulting geometry of the optimisation is already of such high quality, that only minor manual editing of the design is necessary. The usually time intensive redesign of a topology optimisation result is replaced by an automised workflow, that accelerates the design process enormously. The optimisations of the bionic grippers were done in the software Synera.
The gripper for the CFRP roof production at the Landshut plant utilises a mix of different 3D printing processes to take advantage of the unique benefits that each technology offers. The selection of these processes was driven by the technical and economic considerations for the specific components of the gripper. The approach is not to simply ‘print everything’, but rather to use the 3D printing technology that provides the most benefits for each individual component. This strategic approach ensures that the overall gripper design is optimised for both technical performance and cost- effectiveness. For the vacuum grippers and the clamps of the needle gripper used to lift the CFRP raw material, the selective laser sintering (SLS) process was selected. SLS allows for the production of these intricate and complex parts with the required precision and durability.
On the other hand, the large roof shell and bearing structure of the gripper are manufactured using large-scale printing (LSP) technology. LSP is well-suited for producing large, stiff components in an economical and sustainable manner. Furthermore, in a subsequent optimisation step, the weight of the bearing structure was reduced even further. This was achieved by employing aluminium sand casting technology, where 3D printed shapes and cores were utilised. This approach allowed the full potential of topology optimisation to be exploited, leading to a significant reduction in the overall weight of the gripper.
3D printing ‘World’s Largest’ carbon composite rocket on Rocket Lab’s 90-ton 3D printer
Californian space launch company Rocket Lab is using a 90-ton 3D printer to build what are said to be the ‘largest carbon composite rocket structures in history.’ The company’s 3D printer, a custom-built automated fiber placement (AFP) machine, is reportedly the biggest system of its kind in the world. Made in the United States by Electroimpact, the robotic 3D printer is 39 ft (12 meters) tall, and can lay down 328 ft (100 meters) of continuous carbon fiber composite per minute.
Rocket Lab has implemented the large-scale AFP machine at its Space Structures Complex in Middle River, Maryland. It is designed to automate the production of all major composite structures for the company’s reusable Neutron launch vehicle. These include panels for the 91-foot (28-meter) interstage and fairing, the 22.9-foot (7-meter) diameter first stage, and the 16.4-foot (5-meter) diameter second stage tanks.
According to Rocket Lab, while it takes several weeks to build a stage 2 dome using conventional, manual methods, the AFP machine can produce one in just 24 hours. The company anticipates it will save over 150,000 hours when constructing rocket structures with AFP technology.