E-Mobility Engineering 016 l Aurora Powertrains eSled dossier l In Conversation: Thomas de Lange l Automated manufacturing focus l Torque sensing insight l Battery Show Europe 2022 report l Sodium batteries insight l User interfaces focus

and Mechatronics at the Karlsruhe University of Applied Sciences, in Germany, has developed a process that uses industrial robotic arms flexibly and economically to manufacture the harnesses. To reduce the size and weight of harnesses, the cables, connections and plugs are becoming ever- smaller, making manual construction increasingly difficult. So far, the individual cables have been laid on a cable board and bent in certain directions or plugged together. Automating that process is difficult, because previous gripping systems could not grip cables that were not precisely placed or to connect plugs. The German researchers have patented a process that freezes the cables into a rigid state and heats small areas to construct the harness. The cables are shaped by robots that place them on a jig built from controllable, movable and temperature-controlled pins. Cooling can take place in a cooling area or by heating and cooling elements contained in the gripper of the robot. The cables are heated locally at the bending point so that the insulation is not irreversibly damaged during the deformation, after which they are immediately cooled down again to stabilise the bend. The robotic arms can then align the next section of cable with a predefined force. The cables can also be inserted into connectors during assembly without kinking them. This allows the wiring harness to be produced shortly before required and to the latest specification, avoiding delivery times that can be several weeks and shortening the supply chain. If the wire harness can be manufactured within the production run through automation, the so-called one-piece flow also becomes possible, which in turn increases flexibility. Additive manufacturing Another approach to manufacturing wiring harnesses automatically is to use AM. The resulting harness can be lighter, easier to maintain and include the benefits of optimised structural design from design tools. The harness will be integrated into existing surfaces or built around structures that can be assembled by the robots on the automated line. One system being developed uses a 2.5 m 3 temperature-controlled manufacturing cube with high-speed linear motors for five-axis positioning and a range of AM heads. The heads can be 3D-printed lines that are sintered. The motors are controlled to operate at any angle with an accuracy of 10- 20 µm. The calibration software is also automated to eliminate inaccuracies in the frame of the cube, so it is relatively cheap to build, and has large apertures for easy access for the robots to move sub-assemblies in and out. An initial calibration creates a matrix of transformations to provide accurate positioning for the print heads. One prototype of the system with a build volume of 1000 mm 2 has an x-y stage at the top, with a z stage that drops down. At the end of a gantry in the cube is a rotation stage that can pick up any effector, for example a 3D print head for high-temperature fused deposition modelling polymers. This can be used to create grooves for any gauge of wire for a harness 3-4 m in length, with insulation displacement connectors pushing the wire into a block. Depositing a plastic layer on top secures the wire in place and protects against humidity and corrosion from the atmosphere. Flexing on the terminations leads to corrosion, but this approach allows complete control of that. Finite element analysis on the component with the wire means the design can accommodate the flexing and vibration on the termination to reduce damage and corrosion significantly. The next stage is to support printed electronics, using a deposition head to lay down conductive paste for the interconnections, for example on the casing of a battery pack, with another laser head for sintering the paste to create the wires, avoiding the need for an oven to cure the paste. This automates both the manufacture and assembly at speeds of up to 10 m/s, allowing components to be handled by the robots. The software for that is crucial. The slicer software used for most AM equipment does not work in a five-axis system, so a full CAM system such as CNC is necessary, which is not trivial to use. It needs software such as Siemens NX to carve race tracks for printed electronics or wire traps. The software allows the creation of a subset of standard features such as laying down an 8 AWG wire from A to B. However doing that can be more complex for a wiring harness company, so the assembly tool developer can provide the code for it. Automation is only half the story. One EV maker has a general assembly Focus | Automated manufacturing Two-component adhesives are a key technology for the automated production of battery packs (Courtesy of Durr) 40 Winter 2022 | E-Mobility Engineering