Double-laser treatment structures metal surfaces better

22 Mar 2017

Fraunhofer ILT’s eVerest project to develop automotive metal surface processing machine using pico- and nanosecond pulses.

In the automotive manufacturing industry, more and more surfaces are nowadays given a microstructure treatment. Whether these are applied to cylinders or dashboards, functional surfaces are "all the rage", according to the Fraunhofer Institute for Laser Technology (F-ILT), the German laser-materials processing research organisation.

The F-ILT is now leading a project – called eVerest – to develop a laser machine that will be able to efficiently deliver microstructure surface treatments even across large surfaces thanks to a combination of two different pulse types; ultrashort picosecond and nanosecond. The intention is to offer “virtually unlimited” precision. The F-ILT commented, “lasers are the right tool for this job, to ensure that productivity matches precision.”

Technical structures, created by picosecond laser radiation, are finding increasing application in automotive interiors. The F-ILT commented, “Ultrashort pulse lasers have for many years been the tool of choice for processing micromaterials. No matter what the material, ultrashort pulse lasers can ablate even in the micrometer range with high precision. The only catch is that it takes plenty of time concerning the industrial application.”

Up to now, the solution has either been more laser power, faster scanning or splitting the laser beams into multiple beams. A new research and industry consortium involving the F-ILT, is taking a different approach, with partners developing a laser materials processing machine that uses a strict ultrashort pulse laser only for the finest details. The rest of the work is previously done using a productive nanosecond laser.

Automotive sector

A glance into a vehicle’s interior is enough to see that detailed structures convey an impression of exclusivity, says the F-ILT. “For a long time, leather was the dominant look. Now the preference is for fine, more technical structures and most of these 3D parts are manufactured using plastic injection molding,” it stated in the project announcement.

Injection molding tools featuring the required detail in the micrometer range are often produced using photochemical etching processes. The individual stages are repeated over and over, requiring processors with a sensitivity for finesse since they are not reproducible.

This work can also be done using lasers – in particular, nanosecond lasers are able to achieve similar throughput rates to conventional etching processes. But they tend to reach their limits when it comes to precision; they can begin to melt the material leading to rough contours, especially for intricate structures.

Pico and nano combination

Although ultrashort pulse lasers emitting picosecond pulses might not achieve the required throughput rates, they can perform ultra-precise ablation. Finding a way to combine picosecond and nanosecond pulses is the goal of the eVerest research project.

Funded by the German Federal Ministry of Education & Research, the project is aiming to develop a complete machine and system technology for the efficient manufacture of large-format, 3D mold tools for designer surfaces.

The eVerest project, which began in 2016 and is scheduled to run until the end of 2018, involves researchers from two universities working with industry partners. Laser manufacturers, system integrators and an automotive OEM are among those collaborating to develop a complete solution including software, lasers and a machine concept that will support 8-axis simultaneous processing.

Non-expert operation

A key project objective is that it must be possible to operate the machine without having to be an expert in the underlying technology. This would mean a significant advantage over the abovementioned finesse required for etching processes. Ultimately, precision-controlled laser technology paves the way for full automation.

Although the process itself is being developed with partners at Volkswagen, its areas of application extend far beyond the automotive industry. No matter whether they are for embossing rollers for the printing industry or large bearings for the rotor shafts of wind turbines, functional surfaces are in demand in any number of sectors.

Aachen workshop in April

The core topics governing the development of the new systems are an in-depth understanding of the process and how to adapt the process technology. These issues are also the focus of this year’s UKP-Workshop: Ultrafast Laser Technology, which will be held on April 26 and 27, 2017 in Aachen, Germany. This will be the fourth year for the event that brings together specialists in laser development, process technology and the industry at large to discuss their experiences in ultrashort pulse laser research, development and applications.