Process monitoring for laser material processing

© Fraunhofer IPT
Waterjet-guided in-line laser process control for depth-controlled manufacturing of mi-crostructures with high aspect ratios.

Laser processing systems are becoming increasingly important in the industrial production of micro and macro components for various industries and applications and are thus establishing themselves as an important tool for production. Their technical characteristics such as high precision, reliability, material diversity and the low thermal load on the components contribute to this development, as does the good automation capability of the laser process.

The required low component tolerances and short cycle times, however, present laser processing with ever new challenges. The stability of the process plays a major role here: since laser processes are influenced by various machine-, workpiece- and environment-related factors, even small parameter changes can mean that the components produced are no longer within the intended tolerances. Especially in the production of precision components, the process window, i.e. the range of permissible parameter deviations, is extremely narrow. Therefore, thorough monitoring and precise control of the process is essential in laser micromachining.

Our solution

Here Fraunhofer IPT relies on measurement systems based on short-coherent interferometry, camera- and diode-based measurement of process emission, laser triangulation and chromatic confocal distance measurement. Integrated into the laser processing units, they provide direct process monitoring. The measurement systems can use the same beam path of the laser beam or be introduced with an offset or angle. In this way, the modular inline measurement systems can analyze the component before, during and after processing, depending on the measurement principle. These solutions allow accurate, robust monitoring and control of laser processes that can handle even complex tasks.

Our services

  • Development of measurement systems and demand-oriented measurement software
  • Project management, requirements analysis, design and implementation
  • Integration into manufacturing
  • Validation and characterization

Our measuring principles

Chromatic confocal distance measurement

Chromatic-confocal sensors are integrated into machines where workpieces are to be precisely positioned relative to the laser or where the focus is on quality assurance.

Short coherent interferometry

Coaxially integrated sensor technology makes it possible to maintain even low tolerances in production through adaptive process control.

Laser induced plasma analysis

The measurement principle detects the variation of the plasma emission at the interfaces of the layers in multilayer systems and thus makes it possible to control the laser process between the individual laser pulses.

Technical possibilities

Before machining

  • Acquisition of the component position and topography for aligning the workpiece as well as adaptation of the machining strategy and the CNC code
  • Automatic process initialization (laser parameter setting)

During machining

  • In-line detection of the ablation depth
  • Detection of process deviations and control
  • In-line monitoring of the focus position
  • Early identification and correction of manufacturing defects

After machining

  • Quality assurance directly in the machine