Laser systems are known for their ability to process virtually all types of materials; however, hard, brittle, and transparent materials such as glass, sapphire, acrylic fiber, or ceramics present special requirements. "When cutting glass and ceramics, it is essential to consider clean cutting edges, high precision, long-term stability, and, at the same time, the absence of wear on the machining tools," says Georg Hofner, spokesperson for the board of directors of the Scanlab exhibitor at the LASYS trade fair. The unique properties of glass pose a particular challenge for laser systems, as glass is brittle, transparent to visible light, has low thermal conductivity, and, in the case of uneven heating, accumulates stresses that can lead to cracking. "For example, the tempered glass backs of smartphones cannot be cut using conventional methods. In this case, only lasers offer the opportunity to perform efficient and cost-effective cutting processes," says Christof Siebert, head of the micromachining division at Trumpf Laser- und Systemtechnik. According to Trumpf experts, diamond blade cutting has proven to be inflexible. They believe that variable contours are difficult to achieve. Furthermore, they claim that cracks would occur during milling, requiring extensive post-processing and consequently increasing costs. In recent years, it has been demonstrated that ultrashort pulse laser systems are ideal for machining brittle and transparent materials. "Ultrashort pulses in the picosecond and femtosecond range generate no heat, and an efficient process allows for high cutting speeds. Our multi-regulation lasers perform cuts while ensuring high process reliability," Siebert continues.
To ensure high-quality cutting edges and flexible, cost-effective operation, scanning systems such as those from Scanlab are also used. "The combination of ultrashort pulse lasers with scanning systems enables virtually simultaneous machining. Thanks to 'cold' ablation using a scanner, the material to be cut—for example, sapphire crystal—is not melted but directly vaporized. The process takes place by precisely tracing the contour with the scanner and places high demands on the scanning system for accuracy and repeatability," explains Hofner. In his opinion, for fragile and transparent materials, scanning heads with particularly high dynamics and innovative control technology are ideal.
"The scanning system accelerates based on a pre-calculated nominal path, always at the maximum possible acceleration, thus avoiding tracking errors and machining inaccuracies," adds Hofner.
Rofin, a participant in LASYS, is offering a new technology. Dr. Roland Mayerhofer, head of the main research, development, and manufacturing department at Rofin Baasel Lasertech, explains: "Our SmartCleave laser system uses ultrashort laser pulses with specially optimized properties. A laser filamentation process ensures the separation of fragile and transparent materials in a high-speed, residue-free, and gap-free process." It also allows for cutting irregular contours, even with small radii, in a single pass. "This new process is the smart way to reduce mechanical correction work, which is costly in terms of time, money, and labor, to just a few steps," Dr. Mayerhofer comments. These new technologies open the door to a vast array of applications: the field includes, among others, smartphone displays made of tempered and non-tempered glass or sapphire crystal, TV, computer, and tablet screens, LED and OLED products, and other microelectronic components, glass substrates for integrated circuits, optical components, watches, medical devices, architectural and household glass, as well as semiconductors and ceramics.
Another participant at LASYS, Wallburg, is well-suited to the printing industry and many other sectors. "Our system solutions for cutting glass and acrylic fiber, among other materials, enable precise and cost-effective work, as they are flexible and perfectly suited to both individual production and large-scale series manufacturing," says Jürgen Wallburg, managing director of the eponymous company.
For cutting acrylic fiber, it is especially important to use the correct material to avoid stress cracking. "Furthermore, the laser system must allow for precise control and operate with a fast pulse," adds Wallburg, "so that the cutting edge is clean and compact."
The laser sector is highly innovative, a fact that will be evident at LASYS 2016. The refinement of laser systems has enabled the increasingly cost-effective machining of brittle materials. But this is just a small part of the extensive range of laser machining solutions that will be presented at LASYS 2016. At the same time, a comprehensive program will perfectly complement the exhibition. A special feature of the trade fair is the "Stuttgarter Lasertage SLT" event, which bridges the gap between research and industry.
