Fraunhofer Institute for Material and Beam Technology IWS
Fraunhofer Institute for Material and Beam Technology IWS

Processes

Laser Fusion Cutting of Metals

Video: Melt exit of a laser fusion cutting process. © Fraunhofer IWS

Laser fusion cutting is suitable for almost all metals and is based on local heating above melting temperature and expulsion of the liquid material with a directed gas jet. The cutability and resulting performance is determined by the absorptivity of the laser wavelength used thermal conductivity, melting temperature and enthalpy of fusion. Due to a high gas pressure the cut edge has a characteristic groove pattern and a small heat-affected zone. The inert gas minimizes oxide formation in the area of the cut edge. Material thicknesses of up to 60 mm can be cut using this process variant, depending on the material and laser power.
 

Our Research Activity on Optimizing Laser Fusion Cutting Focuses on, e.g: 

  • Increase of the effective cutting speed in the thin sheet area by process optimization and system technical developments
  • Increase of the quality while maintaining the cutting quality in the thick sheet range among other things by the use of dynamic beam oscillation (dynamic beam shaping)
  • Further development of process sensor technology
  • New gas concepts for cutting speeds above 150 m/min (longitudinal cutting)

Laser Flame Cutting of Metals

Laser flame cutting is suitable for all metals that do not form oxygen-tight oxide layers due to oxygen supply. These include, for example, low-alloy structural steels. The process is based on local heating to ignition temperature, which is followed by an exothermic reaction into low-viscosity metal oxide caused by the addition of oxygen. The expulsion of the molten metal is supported by the coaxial gas jet. The cuttability and resulting process performance are determined by matching the temperature of the cutting front and the oxygen supply.

The current object of research is the sensor-based optimization of the process zone temperature and reaction area by means of dynamic beam oscillation to increase quality, speed and cuttable material thickness.

Laser Remote Cutting of Metallic Materials

Laser remote cut gasket.
© Frank Hoehler
Laser remote cut gasket.
Cutting edge of a remote laser cut copper foam.
© Fraunhofer IWS
Cutting edge of a remote laser cut copper foam.

Laser remote cutting of metals is a form of sublimation cutting in which a high proportion of melt is also expelled from the cutting zone. By using high-brilliance cw solid-state lasers, the material is melted. A small proportion of the melt is also vaporized. The expanding vapor provides the expulsion of the melt. The process can be usefully employed for metallic materials in the thickness range between 0.01 and 0.5 mm. Cutting speeds of up to 1200 m/min can be achieved. A characteristic feature of laser remote cutting is the cyclic removal of material from a thickness of approx. 0.1 mm.
 

Our Research Activities Focus on:

  • Process development for customer specific applications
  • Software and hardware development for true-to-path high-speed machining
  • Design of adapted machining systems
     

Applications and Advantages

Typical applications are prototypes and small batches in advance of stamping processes, cutting jobs with high geometric variance and geometries that cannot be stamped.

The advantages of the process are also evident in the cutting of open-pore metal foams for medical implants, heat exchangers or battery systems. The very fast, highly focused heat input and force-free operation enable high-precision and virtually burr-free cuts, without thermal or mechanical deformation. The very short interaction between the soft magnetic material and the laser beam, which is due to the high cutting speeds, enables contour cutting with very little influence on the magnetic properties.

Laser Cutting of Non-Metallic Materials

Laser cutting of three-dimensional glass fiber reinforced plastic component with C02 laser.
© Fraunhofer IWS
Laser cutting of three-dimensional glass fiber reinforced plastic component with C02 laser.
Cutting of cardboard and creation of folded edges by using CO2 laser.
© Fraunhofer IWS
Cutting of cardboard and creation of folded edges by using CO2 laser.

Laser cutting of non-metals is characterized by a very high proportion of sublimated material. For most materials the melting temperature is quickly exceeded and vaporization is reached. The specifics of the cutting process are as varied as the range of materials. The process can be supported by a coaxial gas jet or carried out as cyclical ablation. In addition to solid-state lasers, CO2 lasers are frequently used. One focus of our developments is the application of cw lasers in combination with fast beam deflection via scanners. The process technology developments, which are strongly driven by the control of the introduced heat, are supported by the development of system technology components and control solutions.

The cutting of highly heterogeneous materials, such as carbon fiber-reinforced plastics, is achieved by cyclic ablation with very short interaction times due to high moving speeds of the cw laser beam with minimal heat-affected zones. Depending on the material thickness, processing speeds of several meters per minute can be achieved.
 

Our Research Activities Focus on:

  • Process development for customer-specific applications,
  • Software and hardware development for high-speed web processing and
  • Design of adapted machining systems

The Range of Processable Materials Spectrum Includes:

  • Glass materials
  • Natural fiber materials (wood, paper, cellulose)
  • Polymers (reinforced, non-reinforced, thermoplastic, thermosetting, ...)
  • Ceramics and natural stone
  • Textile materials