Researchers use ultrafast lasers to optimise plug connector production

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A multi-beam module was used to increase the processing speeds of ultrafast lasers for helical cutting. (Image: Fraunhofer ILT).

A group of researchers has developed a new process for cutting thin-walled metal strips using ultrafast lasers as an alternative way to produce plug connectors for vehicles.

Plug connectors are used to transmit signal and control voltages from one part of a vehicle to another. Currently these contact parts are produced in a traditional stamping and bending process. However, the growing number of connector elements now required in vehicles – around several thousand – is increasingly pushing this mechanical method to its limits. In addition, with the continued trend towards miniaturisation, demand is also surging for significantly smaller plug connectors with contact parts that have ever more delicate and intricate structures.

The newly developed cutting process makes it possible to fabricate these contact parts in an eco-friendly, high-precision and efficient manner. By using laser cutting, the researchers have opened the door to design options that were previously impossible to realise, particularly when it comes to creating contact areas with several independently sprung contact points in tiny installation spaces.

The new process features ultrafast lasers being used to perform helical drilling. This method, developed by Fraunhofer ILT, has already shown itself to be an excellent option for producing high aspect ratio precision micro-holes in steel, glass and ceramic. With a focus diameter of 25μm and a roughness Ra at the borehole wall of less than 0.5μm, precision is one of the greatest strengths of helical drilling. This high level of quality can only be achieved at low process speeds, however.

Increasing the speed of this process was therefore the focus of the three-year ScanCut project, which was completed in February. In addition to Fraunhofer ILT, project partners included ultrafast laser manufacturer and Trumpf subsidiary Amphos, laser system and optical module manufacturer Pulsar Photonics, and Kostal Kontakt Systeme, a company that previously manufactured plug connectors using traditional stamping and bending processes.

Kerf produced by helical cutting on a metal sheet. (Image: Fraunhofer ILT)

‘In the project, we combined our helical drilling optics with a multi-beam module from Pulsar Photonics and a high-power beam source from Amphos,’ said Jan Schnabel, scientist in the Micro and Nano Structuring group at Fraunhofer ILT. ‘That allowed us to combine the precision and quality of the helical drilling process with the productivity of multi-beam processing.’

The Amphos high-power beam source is based on InnoSlab technology, and offers an output power of 300W and a pulse energy of 3mJ. The high pulse energy is necessary to divide the laser beam into as many as 20 individual beams for parallel processing, which has been shown to increase the productivity of ultrafast lasers

The project partners focused in particular on the possibility of automation. ‘We implemented electrically adjustable mirror and optics mounts to enable automatic adjustment of the beam position,’ said Schnabel. ‘Once we have programmed a suitable software routine, adjustments to the helical drilling optics can be initiated at the touch of a button without any of our staff having to travel to the site.’

A follow-up project is now planned in which Pulsar Photonics and Fraunhofer ILT will continue developing the helical cutting technology with multi-beam processing. The insights obtained from the project will also be used to develop high-power beam sources to expand the portfolio of products offered by Amphos.

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