SCANLAB Galvo with digital se-Encoder

Controlled dynamics for additive processes

High-speed scanning systems are key components for higher productivity and quality in industrial additive manufacturing (AM).

Among other things, efficient electric drive systems will be needed to provide green electricity for future mobility and industrial processes. Additive manufacturing (AM) will help manufacture these systems: for example, an EU-funded research consortium, with the participation of Scansonic MI, plans to apply magnetic structures additively on to the rotor surfaces of electric motors rather than attaching pre-fabricated permanent magnets. The design freedom of AM allows better utilization of installation space as well as higher power densities and endurance strength. The new approach will also reduce assembly times, which will, in turn, mean that the drives can be produced less expensively.

The project is in vogue: laser-based additive metal printing processes are being used in an increasing range of industries. After the initial prototypes, the aim is now to begin mass-producing components. To speed up development, AM plant construction companies are working together with suppliers and research institutes to increase the productivity and reliability of the new technology. Key components are scanning systems, which in state-of-the-art AM plants shape the beams of up to twelve 1000-watt lasers working in parallel and guide these towards the components with the help of galvanometer mirrors. This is a high-speed process: the laser beams flash on a bed of micrometer-sized (µm) metal powder while tracing the contours of the component that is being shaped. In this selective process, lasers weld the powder layer by layer to create the complex components.

More speed, precision and increasing process monitoring

Digitally controlled two and three-axis scanning systems based on highly accurate galvano drives ensure speed, precision and productivity. Their dynamic beam forming and guidance allows the size of laser spots to be varied during the process. RAYLASE offers a system with which the spot diameter can be varied between 40 and 150 µm with precise track pitches in the low single-digit µm range. The company has also developed a camera-supported process monitoring system: 38,000 images per second keep the selective laser melting material on the powder bed. In addition to the high-speed camera, a pyrometer provides temperature data from the melt pool. Based on the sensor data it will be possible to continuously regulate the laser power and mirror position in the scanner head – for example, to ensure a more homogeneous structure of the µm-thin metal layers with the help of controlled spot size and temperatures.

SCANLAB – a pioneer in metal printing for 30 years – also produces quality-assured AM processes. The key to this are scanning systems that the company continuously develops. In addition to pyrometers and camera systems, the developers also use OCT (optical coherence tomography) sensors for topological measurement of the powder bed and components. Via smart interfaces, they integrate their data into the scanning system controls to optimize process control. Because the systems also measure the exact position data of the laser beams and all field and lens corrections of the scanning optics, it is possible to ensure almost complete quality monitoring.

Vision: sensor-supported real-time control in additive processes

Quality inspectors still use this possibility to look for documented inconsistencies, for instance, after faults have been discovered in the metal structures of components; time axes and topological data guide them immediately to the suspicious area. But process monitoring also opens up further possibilities: for example, sensor data could provide a basis for adjusting the process parameters after a layer has been completed to rectify faults in the ongoing process. In the future, the digitally networked, smart scanning systems will pave the way for real-time control of additive processes and, with the help of sensor data, will enable automated, fault-free additive manufacturing. Exhibitors at LASER World of PHOTONICS, such as Cambridge Technology, RAYLASE, SCANLAB, and Scansonic MI are the driving forces behind this rapidly approaching production technology of the future.