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Ultra Dynamic Optical Systems for High Throughput Laser Surface Processing

Periodic Reporting for period 2 - ultraSURFACE (Ultra Dynamic Optical Systems for High Throughput Laser Surface Processing)

Reporting period: 2017-07-01 to 2019-06-30

In nearly every sector of industrial manufacturing a broad spectrum of surface processing techniques is used, e.g. for structuring, coating or polishing of aesthetical or functional surfaces. In the last years laser based surface processing techniques have made tremendous technical progress and are now entering industrial manufacturing on a broad scale.
But for many applications the low throughput is still limiting these techniques.
The idea of ultraSURFACE is to increase the throughput for laser surface processing by at least a factor of 10 without any drawbacks in the quality of the processing results. Therefore two different optics concepts have been realized and combined with a fast and synchronized machine, scanner and optics control.
Optics Concept 1 (Beam-Shaping optics) refers to a dynamic and flexible beam-shaping approach with piezo-deformable mirror which should enable the realization and the fast adaption of application specific intensity distributions for laser polishing and laser thin film processing.
Optics Concept 2 (Multi-Beam optics) is a beam splitting approach which allows simultaneous processing with multiple laser beams for laser structuring.
Finally the utilisation of the ultraSURFACE optics for surface processing of end-users 3D parts for demonstration of throughput increase was tested.
Overview of achieved results within the project:
- Concepts for both mentioned optical systems were developed:
- The concept for the beam-shaping optics is based on a shaping of the raw Gaussian beam via a DOE (diffractive optical element) and the adaption to the work piece geometry using a deformable mirror. By this an individually shaped intensity distribution should be achieved with keeping the process conditions constant also on freeform surfaces.
- In case of the multi-beam optics a DOE is used for splitting a Gaussian beam into four equal beams. Each of the four beams is individually controllable in all three Cartesian directions via using a spot position control unit. For the lateral position this is achieved by using two rotating glass plates. For the vertical shift (parallel to the optical axis) this is done by using a movable lens.

- A 5-axis laser machine tool with an integrated measuring probe for defining the work piece coordinate system was designed and build up. The CAM-NC data chain was enhanced and provides the tool path data for laser processing of 3D-parts for all three laser processes and both optics.

- For both optics a prototype has been developed and characterized. After some improvements the Multi-Beam optics could be integrated into the 5-axis machine and parts of the end-users could be laser structured successfully. With the Beam-Shaping optics, it was not yet possible to process 3D parts of the end-users, as different problems arose, which could only partially be solved within the scope of the project. The following problems could not be solved within the framework of the project and currently prevent the use of Beam-Shaping optics:
- Originally not planned realization of the intensity distribution via a DOE, which must be rotatable, so that the intensity distribution can be aligned to the scan direction, represents a clearly more complex approach (both for the adjustment and for the control of the system). One problem is that the intensity distribution did not rotate around its center, so that a meander-shaped laser polishing was not possible. Design and manufacturing of additional components for beam guidance in order to optimize/correct the alignment of the laser beam into the hollow shaft motor was done, but no longer integrated and adjusted into the Beam-Shaping optics within the scope of the project.
- Hysteresis effect of the deformable mirror (inherent to the piezo-materials) makes a feedforward control challenging and will require modification of the mirror controller.
- Intensity distribution does not meet the requirements, especially for thin-film applications.
Thus the Beam-Shaping optics needs further improvements
In order to give the end-users at least the opportunity to evaluate the quality of laser-processed components, other laboratory set-ups (state of the art) were used to process 3D parts.

- Different application tests on the laser structured parts were performed at the end-users and showed promising results. For both applications of the end-users a reduction of the processing time by a factor of 3 was achieved using the Multi-Beam optics. Although the goal of a 10-fold higher throughput is not achieved with this example product, the cost savings are nevertheless considerable. For the consideration of a concrete case a cost reduction of 58 % results.

In sum three prototypes were built within ultraSurface (Beam-Shaping optics, Multi-Beam optics, 5-axis laser machine tool). The commercial exploitation of the Beam-Shaping optics is not possible with the current prototype result, as the basic goals could not be demonstrated. However, the market potential for a high average laser power beam shaping system is still very attractive for a lot of different applications (polishing, additive manufacturing, welding, surface treatment). Thus further research especially on the deformable mirror is planned in order to increase the TRL-level of this technology.
In nearly every sector of industrial manufacturing, surfaces of parts are processed e.g. polished, coated, or structured. ultraSURFACE addresses the entire market of laser industrial manufacturing and enhance throughput as well as flexibility significantly.
The impact of ultraSURFACE will have strong influence on the following branches of industries: automotive industry, mechanical engineering, consumer products.
It provokes a significant reduction of manufacturing costs and time and strongly enhances throughput. The processing costs for laser structuring have been reduced by at least 50 % in comparison with conventional techniques.
Furthermore ultraSURFACE will improve working conditions in the sector of surface processing by
- reducing noise disturbance and dispersible dust – especially heavy metal dust
- no usage of chemicals solutions
- reducing CO2 emission up to 80 %.
Thus the project will have a significant contribution to promote green manufacturing in Europe.
laser structured hydrophobic surface,laser polished blow mould,laser functionalised thin-films
Overall concept of ultraSURFACE
Optics concepts of ultraSURFACE
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