Ablation and Joining

Here you will find videos from the research area ablation and joining.

Photonic Process Chain for efficient ultrashort pulse surface texturing

Photonic process chain with USP structuring, cleaning and polishing.

Industrial laser texturing is currently still dominated by nanosecond lasers. New approaches show that by means of ultrafast laser sources the productivity of nanosecond lasers is exceeded by a factor of 4 while maintaining the same quality. A removal rate of up to 20 mm³/min with a surface roughness of Ra = 1.5 µm can be achieved. Even roughnesses of < 0.5 µm can be achieved with a ablation rate of up to 10 mm³/min. The photonic process chain shows that with the universal tool of an ultrafast laser, subsequent processes such as cleaning and polishing can also be carried out in the same machinery without time-consuming set-up or re-clamping of the workpiece.

 

More Information about the eVerest project

Article "Efficient production of design textures on large-format 3D mold tools"

CarboLase – Photonics meets textile engineering

Carbon fibre-reinforced (CFRP) components are normally assembled by fasteners that are glued into the cured and drilled CFRP component. The integration of the fasteners into a textile preform and an additional curing process to produce the final CFRP component can shorten production process chains. This requires high-precision cut-outs in the textile for the fasteners. In the NRW-based project CarboLase, funded by OP.EFRE, laser material processing is integrated for the first time into an automated preforming process. A novelty in the process is the use of the material-friendly ultrashort pulsed laser, which processes the textiles without damaging them thermally. By combining the technologies in a flexible robot cell, just-in-time production of CFRP components with integrated fasteners is now possible independent of component geometry and batch size.

 

Technology Demonstrator Polymer Processing

With the demonstrator the various applications of laser technology in the processing of plastics can be demonstrated:

  • Cutting of PMMA in different material thicknesses (0.3, 1 & 2 mm) with a CO2 laser
  • Removal of PMMA in the form of microfluidic structures with a CO2 laser
  • Absorber-free laser transmission welding of PMMA with diode laser radiation (λ=1660 nm)
  • Laser microstructuring of stainless steel (1.4301) with fiber laser radiation (λ=1064 nm)
  • Joining of a plastic-metal hybrid connection with diode laser radiation (λ=940 nm)

All laser-based processes are characterized by a high degree of flexibility, an energy deposition that can be precisely adjusted in terms of location and time, and a high degree of automation.

Cutting of Thermoplastic Composites

Fibre-reinforced plastics (FRP), the use of which is becoming increasingly widespread due to their great lightweight construction potential, generate high tool wear during mechanical processing by milling or drilling, which is avoided by non-contact laser cutting. The cut 1 mm thick composite material is made of polypropylene, which is also reinforced with glass fibres.

Quasi-Simultaneous Irradiation during Laser Transmission Welding of Absorber-Free Plastics

The challenge in laser transmission welding of two optically identical plastic parts lies in the selective heating of the joining area in order to avoid component distortion and burns on the irradiated surface. As a rule, a highly focusing fixed optic is used for this, which, however, can only be guided over the component with contour accuracy up to a certain speed due to inertia. Scanners offer higher dynamics, however, with which the beam cannot be focused sufficiently strongly. This restriction can be overcome by irradiating the welding contour quasi-simultaneously and thus achieving selective heating of the joining area by heat accumulation.

Strategies for Drilling with Laser Beams

Depending on the component thickness and the required quality (precision) and productivity (drilling time), holes with diameters from 1 µm up to several millimeters can be achieved by using single-pulse drilling, percussion drilling, trepanning or helical drilling. The single pulse drilling can be performed "on-the-fly", so that up to 300 holes per second with a diameter of e.g. 60 microns in 1 mm thick material can be achieved. Larger hole depths can be achieved by using percussion drilling. For hole diameters larger than 300 microns, trepanning is used where a relative movement between the workpiece and laser radiation occurs. Holes with high precision concerning geometry and high metallurgical quality are achieved by using helical drilling.

Laser-Beam Drilling of a Jet-Engine Nozzle

Approximately 74,000 holes with a diameter of 1.5 mm shall be drilled into the primary nozzle of a jet engine by using laser radiation. The drilling technique trepanning is used. The nozzle has a diameter of about 900 mm and a length of about 350 mm. The holes will be drilled distributed into 2048 rows, each with 36 holes around the circumference of the nozzle. The nozzle with a material thickness of 1.5 mm is made of titanium alloy Ti 6-2-4-2.

ultraSURFACE – first application tests for laser structuring with the developed MultiBeam optics

Funded by the European Union, the ultraSURFACE project focuses on optimizing optical systems with dynamic 3D applicability and on developing strategies for laser-based production processes with high-throughput. In the project, Scientists and industry partners are developing two new optical designs which allow users to adapt laser beam manipulation individually and to increase throughput by a factor of ten compared to conventional processes. The video shows first application tests for laser structuring with the developed MultiBeam optics, which were integrated into a machine tool at Unitechnologies.

Laser Ablation of an Arbitrary Geometry on ZERODUR®

With pulsed CO2 laser radiation (Q-Switch), ZERODUR®, a glass ceramic material, can be precisely processed. The material removal in the example shown was realized with the following parameters:

  • Repetition rate ≤ 150 kHz
  • Pulse peak power about 20 kW
  • Pulse duration about 300 ns

Laser ablation and laser polishing of glass offers flexible and cost-effective alternatives to conventional manufacturing processes. Laser-based ablation processes can be used both for shaping and for shape correction polishing (Laser Beam Figuring).

Diameter of the machined geometry: 50 mm

Laser Ablation of an Arbitrary Geometry on Fused Silica

When fused silica is processed with CO2 laser radiation, the laser radiation is absorbed in a thin surface layer of the workpiece so that the temperatures can be raised up to the material’s evaporation temperature. If the fused silica is heated locally by the interaction with the laser radiation above the evaporation temperature, material can be ablated. Pulsed CO2 laser radiation (Q-switch) with these parameters was used for the laser process shown in the video:

  • Repetition rate ≤ 150 kHz
  • Pulse peak power about 20 kW
  • Pulse duration about 300 ns
  • 0.1 to 50 µm ablation depth per layer
  • 1 to 3 mm3/s Ablation rate

Sample size: 20 mm x 20 mm x 5 mm

Laser Ablation of a Lens Array on Fused Silica

With the laser process shown in the video an arrangement of defined lens geometries on fused silica was generated. The material was ablated with pulsed CO2 laser radiation (Q-switch) and these parameters:

  • Repetition rate ≤ 150 kHz
  • Pulse peak power about 20 kW
  • Pulse duration about 300 ns
  • 0.1 to 50 µm ablation depth per layer
  • 1 to 3 mm3/s Ablation rate

Laser ablation offers the advantage of contactless processing. High costs for grinding tools are therefore avoided by an almost wear-free tool during laser ablation. Local ablation can generate not only free-form surfaces but also steep flanks for structuring the back of optics, for example to reduce weight.

Sample size: 90 mm x 90 mm x 4 mm

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