Ultrashort laser pulses for industrial mass production - manufacturing with laser flashes

(f.l.t.r.) Dr. rer. nat. Jens König, Prof. Dr. rer. nat. Stefan Nolte, Dr. sc. nat. Dirk Sutter

Dr. rer. nat. Jens König (Spokesperson)
Prof. Dr. rer. nat. Stefan Nolte
Dr. sc. nat. Dirk Sutter

Robert Bosch GmbH, Schwieberdingen
Friedrich-Schiller-Universität Jena, Fraunhofer IOF, Jena
TRUMPF Laser GmbH + Co. KG, Schramberg

Light is a versatile tool. In manufacturing applications, laser beams can replace conventional mechanical machine tools for boring, cutting or even welding. They make the machining of materials fast, cost efficient and, above all, precise. But how can the highest precision with maximum productivity be achieved with ultrashort laser pulses?

Dr. Jens König, Dr. Dirk Sutter and Prof. Dr. Stefan Nolte have mastered this challenge: they developed ultrashort laser pulses for industrial applications. These lasers emit light in the form of high-energy laser pulses no more than a billionth of a second in duration. They have thus paved the way for the very precise manufacture of minute structures – and for the industrial production of innovative products. Jens König is group leader for laser material processing and joining technology in the Research and Preliminary Development division of Robert Bosch GmbH in Schwieberdingen. Dirk Sutter heads Research and Development of ultrashort laser pulses at TRUMPF Laser GmbH + Co. KG in Schramberg. Stefan Nolte is a professor at the Institute of Applied Physics at the Friedrich Schiller University of Jena as well as at the Fraunhofer Institute of Applied Optics and Precision Mechanics in Jena.

Lasers are excellent for applications involving the cutting and joining of different materials, such as metal, glass or plastic. The intense focus of the laser beam has its advantages over conventional tools: there is no point of contact between the ‘tool’ and workpiece, the laser is not susceptible to wear, work pieces are not subjected to as much heat or mechanical strain. Laser processing always maintains the same level of quality, even for the smallest structures. Multi kilowatt lasers are used in the machining of sheet metal no more than several millimetres thick. They can no longer be used where higher level of precision is required, for example, for bores with a diameter of 50 micrometers or less. The amount of energy required to remove the material would always lead to the material’s melting. Since melting is difficult to control technically, inaccuracies can result: burr, sagging or bulging. The surrounding material is also subjected to greater strain due to heat, and reworking is frequently required.

These difficulties can be avoided by using ultrashort laser pulsess. Since their light pulses are only a few piko or femto seconds long (a billionth or trillionth of seconds), but of extremely high energy, the impact of the laser beam on the material is highly concentrated. The result: the material subjected to this kind of laser pulse evaporates without melting. Material is removed precisely and only where desired - micrometer for micrometer. This “cold” machining prevents unwanted effects and means extremely precise machining in very small spaces is possible. Complicated and expensive reworking of products is unnecessary.

Stefan Nolte with his research into the fundamental physical effects has laid the scientific basis for use of the ultrashort laser pulses in material processing. Dirk Sutter and his team developed the world’s first and to date most powerful ultrashort laser pulse for industrial applications. Jens König and his colleagues at Bosch have researched the specific requirements and together with TRUMPF have defined the laser’s specifications to cover every aspect of material processing. Bosch also designed the system technology for reliable industrial manufacturing of numerous products – for example fuel injectors for engines with extremely fine nozzle injection holes. Ultrashort laser pulses from Trumpf are also used in vast numbers in the production of today’s smart phones, and in the manufacture of stents – medical implants used to keep arteries the body open – made of easy to tolerate and bio-absorbable polymers. Many other applications are already in use or are soon to be used in industrial applications.