Thomas Himmer

A comparative study on fusion cutting with disk and CO2 lasers

In recent years, several studies on laser beam fusion cutting demonstrated significant differences in the characteristics of the well-established CO2 laser cutting and cutting with solid-state disk and fiber lasers. The reasons for the observed differences in cutting efficiency and cut edge quality are still the subject of the current research and not finally clarified. In order to further the understanding of the involved phenomena, a series of cutting experiments with CO2 and disk lasers was carried out using a Design of Experiment (DoE) approach. The particular feature of the applied experimental setup was the similar geometry of both the CO2 and the disk laser beam with comparable values of the focus diameter and the Rayleigh length. Cutting trials on cold work steel test specimens with different sheet thicknesses were performed. The extensions of the generated cut kerf and of the heat-affected zone as well as the recast layer were analyzed in order to reach a better understanding of the physical mechanisms which take part in the cutting process. The experimental evaluation of transmitted and reflected energy losses throughout the kerf was realized by means of PMMA (Polymethylmethacrylate) blocks placed under the sheet during the cutting process.In recent years, several studies on laser beam fusion cutting demonstrated significant differences in the characteristics of the well-established CO2 laser cutting and cutting with solid-state disk and fiber lasers. The reasons for the observed differences in cutting efficiency and cut edge quality are still the subject of the current research and not finally clarified. In order to further the understanding of the involved phenomena, a series of cutting experiments with CO2 and disk lasers was carried out using a Design of Experiment (DoE) approach. The particular feature of the applied experimental setup was the similar geometry of both the CO2 and the disk laser beam with comparable values of the focus diameter and the Rayleigh length. Cutting trials on cold work steel test specimens with different sheet thicknesses were performed. The extensions of the generated cut kerf and of the heat-affected zone as well as the recast layer were analyzed in order to reach a better understanding of the physical mech...

High brightness lasers in cutting applications

Laser cutting machines with linear motor drives provide high contour accuracy and high cutting rates. Thus laser beam cutting has become increasingly competitive compared to mechanical precision cutting [1]. Since the several years, new laser beam sources are available for cutting. One of the promising solutions is cutting with fiber lasers. The fiber laser has several advantages such as absorption rate, power efficiency, fiber delivery, better focusing if compared to the CO2 laser.During the recent years, the system technology for laser beam cutting was upgraded at Fraunhofer IWS Dresden [2]. In particular, a precision 3D-laser cutting system with linear drives, robotic systems and several fiber lasers have been installed.Within the frame of several research projects laser beam cutting with CO2-and fiber lasers has been investigated in order to compare the cutting quality and cutting performance of two beam sources. Objective of these studies was to find out if the cutting quality is sufficient and if the requested cutting rate can be obtained.It could be learned that the cutting quality for both lasers is good. The edge quality is sufficient for most of the materials and thicknesses. However, using single and multimode fiber lasers in the kilowatt range can increase the cutting speed and can thus reduce the cutting time [3][4].This paper describes the gained user experience of Fraunhofer IWS. Various beam sources are compared and evaluated with respect to specific applications. Moreover, the advantages and disadvantages for material processing applications will be explained.Laser cutting machines with linear motor drives provide high contour accuracy and high cutting rates. Thus laser beam cutting has become increasingly competitive compared to mechanical precision cutting [1]. Since the several years, new laser beam sources are available for cutting. One of the promising solutions is cutting with fiber lasers. The fiber laser has several advantages such as absorption rate, power efficiency, fiber delivery, better focusing if compared to the CO2 laser.During the recent years, the system technology for laser beam cutting was upgraded at Fraunhofer IWS Dresden [2]. In particular, a precision 3D-laser cutting system with linear drives, robotic systems and several fiber lasers have been installed.Within the frame of several research projects laser beam cutting with CO2-and fiber lasers has been investigated in order to compare the cutting quality and cutting performance of two beam sources. Objective of these studies was to find out if the cutting quality is sufficient and if th...

Opportunities to enlarge the application area of remote-cutting

Remote-Cutting is an alternative method to conventional laser cutting processes when working on thin sheets. Working without any cutting gas the inertia can be reduced significantly. Deflected by two mirrors the laser beam becomes more flexible in the working envelope of the scanner. Depending on the sheet thickness cutting speeds of about 100 m/min in contours are possible [1], [2], [3].The target of this paper is to give some opportunities to enlarge the application area of remote-cutting. It will be shown how the maximum separable thickness can be increased. Furthermore, possibilities to widen the working area are shown. Investigations were done to determine the parameters, which have effect on the cutting quality. Obtained qualities and quantities are compared with those of conventional technologies.Moreover, investigations were done in order to determine the possibility to cut various materials. For example, the selective cutting of material compounds is described. This technology is also known as “Kiss-Cutting”. Using “Kiss-Cutting” improves the handling of thin metal foils and thus the productivity.Remote-Cutting is an alternative method to conventional laser cutting processes when working on thin sheets. Working without any cutting gas the inertia can be reduced significantly. Deflected by two mirrors the laser beam becomes more flexible in the working envelope of the scanner. Depending on the sheet thickness cutting speeds of about 100 m/min in contours are possible [1], [2], [3].The target of this paper is to give some opportunities to enlarge the application area of remote-cutting. It will be shown how the maximum separable thickness can be increased. Furthermore, possibilities to widen the working area are shown. Investigations were done to determine the parameters, which have effect on the cutting quality. Obtained qualities and quantities are compared with those of conventional technologies.Moreover, investigations were done in order to determine the possibility to cut various materials. For example, the selective cutting of material compounds is described. This technology is also known as “K...