ISMR March 2021 | Page 17

FOCUS ON INNOVATION

Additive manufacturing of multi-functional parts

Additive manufacturing is currently one of the most significant trends in industry . Now , a team from the Fraunhofer Institute for Ceramic Technologies and Systems IKTS has developed a Multi Material Jetting ( MMJ ) system that allows different materials to be combined into a single additively manufactured part . This makes it possible to create products with combined properties or functions . The new system can be used with particularly high-performance materials such as ceramics and metal .
“ Right now , we can process up to four different materials at a time ,” said Uwe Scheithauer , a researcher at Fraunhofer IKTS . This opens the door to a diverse range of applications , allowing companies to produce highly integrated multi-functional components with individually defined properties .
The new system fabricates parts in a continuous process . In the first step , the ceramic or metal powder from which the part will be made is distributed homogenously in a thermoplastic binder substance . The slurries produced in this way are loaded into micro-dosing systems ( MDS ) to commence the actual manufacturing process . These slurries are melted in the MDS at a temperature of around 100 degrees Celsius , creating a substance that can be released in very small droplets .
The IKTS researchers also developed a corresponding software program to ensure precise positioning of the droplets during manufacturing . The micro-dosing systems operate in a high-precision , computer-controlled process , depositing the droplets one by one in exactly the right spot . This gradually builds up the part drop by drop at rates of up to 60mm and 1,000 drops per second . The system works with droplet sizes of between 300 and 1000μm , creating deposited layers with heights of between 100 and 200μm . The maximum size of parts that can currently be
manufactured is 20 × 20 × 18cm .
The new IKTS system can be used to make highly complex parts such as the ignition system in a satellite propulsion engine made of ceramics . MMJ also has plenty of conceivable applications in the consumer products market . It is also suitable for more than just manufacturing multifunctional components , such as making blanks for carbide parts ( requiring very little subsequent grinding ).
Left : Material deposition at a rate of up to 1,000 drops per second .
Schematic illustration of the micro-dosing systems .

Smooth human-robot collaboration

Robots are being deployed in more and more situations , many of which involve collaboration between humans and robots – for example , relieving humans of onerous tasks in the workplace . The challenges are how to integrate the robot into the working environment and how to operate it . In a joint project with Volkswagen AG , the Fraunhofer Institute for Telecommunications , Heinrich Hertz Institute , HHI , will demonstrate the advantages that the use of humanrobot collaboration ( HRC ) can bring to the inspection of welding seams in the automotive industry .
Flawless welding seams are a critical quality criterion in automotive engineering . In the future , welds will be inspected by a human-robot team , with each contributing its specific skills and expertise . Controlled by gesture and voice commands , the robot will hold and manoeuvre the specific components into position , while the employee marks and records any defects in weld quality .
The joint research project EASY COHMO ( Ergonomics Assistance Systems for Contactless Human-Machine-Operation ) draws on many years of experience that Fraunhofer HHI has accumulated in 3D capture , 3D information processing and 3D visualisation . This system for the visual inspection of welding seams on key components in automobile production offers a good example of how HRC can function in the industry . In the coming years , this technology will be providing concrete assistance with inspection procedures at Volkswagen .
The robot presents the workpiece ergonomically to enable easy inspection . © Fraunhofer HHI .
The middleware developed by Fraunhofer HHI coordinates the various sensors that serve to capture the overall work situation . Based on the employee ’ s position and gestures , the software calculates the required movement of the robotic arm . This also ensures user safety . For example , whenever the employee ceases to look directly at the component , the software halts the robotic arm as a precaution .
“ The robot can also be set to respond to personalised instructions ,” explained Paul Chojecki , project manager at Fraunhofer
HHI . “ Our new perceptual interface can process a user ’ s individual gestures and voice commands . This means that the system can be quickly customised to a workstation ’ s specific requirements .”
Gestures are used to mark , categorise and confirm defects on the component . By means of precise object tracking and projector-based augmentation , employees are provided with an interface directly on the component , in their working space area . This offers an efficient and intuitive way of generating a digital 3D record of any defects in the welding seams .
“ With the new procedure , any defects can be immediately entered into the system and then statistically evaluated . This means that systematic defects are more rapidly identified and can thereby be eliminated at the welding stage ,” said the specialists at Fraunhofer .
The system features a large number of sensors , combined with multimodal controls based on an enhanced middleware along with customised operating instructions and machine learning . It is an approach that could well bring the breakthrough for further HRC applications – and also expand the scope for collaboration and interaction between humans and robots . Further areas of use include milling machines , for instance , or interactive robotic assistants in nonindustrial settings e . g ., in the healthcare or services sectors .
ISMR March 2021 | sheetmetalplus . com | 17