TISSUE – Titanium Implants Surface Structuration by new gigahertz Ultrashort lasers Efficient process

Aim: To demonstrate the potentiality of this technology for the fabrication and texturization of titanium implants and other potential applications and materials.

Challenges: The current technology (EDM- electrical discharge machining) takes 15 hours to texture one part, is rather not flexible and needs a lot of consumables. Furthermore, in terms of quality, the current technology reaches a minimum feature size of 1 µm. Ultrafast lasers emitting ps- and fs-long pulses can be used to obtain such textures generating LIPSS: Laser-Induced Periodic Surface Structures but they can be limited by relatively low throughput. Repetition rates of a few tens or hundreds of kilohertz to avoid problems of thermal effect accumulation or plasma formation that degrade performance or reduce efficiency are typical process parameters for laser micromachining. GHz bursts of lower-energy ultrashort pulses, despite the very promising experimental results, are a rather poorly explored territory and opens for a great variety of parameters (fundamental frequency, burst lengths, bursts shapes, pulses overlapping…) that need to be optimized.

Benefits: This experiment targets the reduction of cycle time per one part below 10h and aims at reducing the minimum feature sizer for an increased quality down to 0.4µm. GHz bursts of lower-energy ultra-short pulses can help in reaching productivity of ns-lasers while maintaining quality of femtosecond machining. Thanks to the advantages provided by the technology developed in TISSUE, it will be possible to replace the EDM technology which is less flexible than laser and need more consumables, with a faster solution. In addition, such technology paves the way to digitalisation of the manufacturing (closed-loop control) and the complete understanding of the behavior of this process for different materials based on a broad variation of different parameters, will open the way to various application fields (photovoltaics, electronics, batteries…).

Activities & Present achievements: In TISSUE, the GHz regime will be studied on different materials like titanium and aluminum (for RESCOLL), tungsten carbide (for CERATOOL) but also glass, polymers and copper. This laser process is based on a new type of interaction called “cold ablation”. By using an adjustable burst mode, it will then be possible to optimize the process for a given material. The flexible laser from EURO-MULTITEL combined with LASEA system will permit to explore this regime.

Current Status: Both Deliverables for the technology development stage were completed on time and passed the acceptance criteria agreed. A set of laser specifications have been established and communicated to Euro-Multitel. Based on the specifications of the Gigahertz femtosecond lasers collected in the literature and the results obtained in the Laser4Surf project, Euro-Multitel, Lasea and Rescoll have defined the laser specifications that will be developed in the TISSUE project.