Laser Machining Technology Research Articles

New laser machining technology of Al2O3 ceramic with complex shape

A new method was developed for the fabrication of complex-shaped Al2O3 ceramic parts by combining laser machining and gelcasting technique. The unwanted ceramic powders parts were selectively removed by laser machining specified by a computer program, and the gelcast Al2O3 green bodies were machined to a designed shape by a CO2 laser at a wavelength of 10.6μm. The influences of solid loading, laser output power, scanning speed and nitrogen purge on the machining of green Al2O3 ceramic bodies were studied. The experimental parameters were optimized, the green Al2O3 bodies with solid loading of 40vol% or below were easier to be machined, while the green bodies with solid loading of 45vol% or above were hard to be further machined due to the surface sintering. Better machining quality and deeper machining depth could be obtained when the laser power is 30W. The green Al2O3 bodies with complex shape were obtained by the laser machining.

FEM Simulation Technologies of Laser Cutting Wood Board Based on ANSYS

Laser cutting is an important application field of laser machining technology. It can improve machining quality and save time by using a computer to simulate the machining process to obtain the optimal process parameters. In the paper, the FEM simulation techniques for laser cutting are discussed by taking wood as an example and using the FEM software ANSYS as a simulation tool. The technologies include solid modeling, finite element meshing, loading of the moving laser source and secondary developing of APDL language. laser cutting; finite element method; simulation

R2R Technology for Organic Electronics and Photovoltaics

The development of the new material group of conductive polymers has lead to the coverage of whole new areas of applications. For some years cheap mass fabricated printed electronics have been researched. 3D-Micromac AG develops processes for micromachining of thin films of conductive polymers in roll-to-roll-technique by laser. As already low pulse energies in the range of ∼10μJ at a spot diameter of 50μm are sufficient, high repeating ultra-short pulse lasers (pico- and femtoseconds) can be applied. With this kind of lasers excellent results at high machining speeds can be achieved.An example for the laser structuring of thin films on flexible substrates is the generation of all necessary insulation cuts (P1, P2, P3) in flexible solar cells. Such cuts are done with highest precision and without damage to the underlying layers. Currently used mechanic structuring technologies which provide unsatisfying quality and processing speeds can thereby be replaced with a superior laser machining technology that provides higher quality and machining speeds. By using roll-to-roll systems, high repeating lasers and the socalled “on-the-fly” technology for compensation of reel movement through-put can be significantly increased and as a result the costs for the end-costumer will be more attractive. The lecture presents the results of the process and machine development which will be demonstrated by the example of micromachining of thin films on flexible substrates e.g. flexible solar cells.

A novel laser micro/nano-machining system for FPD process

Laser machining technology has potential to be adopted as micro- and nano-fabrication equipments in the field of flat panel display (FPD) industry. The equipments repair short, open or protrusion defects by cutting and welding using high-power laser. The equipments should be able to carry large sized mother glass and have high productivity and accuracy. To meet the requirements, the equipment should travel long range with higher speed and higher precision than the conventional. In this paper, a high precision decoupled dual-stage is proposed to transfer and position FPD mother glass. The dual-stage system consists of coarse stage actuated by linear motor and fine stage by moving magnet type voice coil motor. The control and design of the two stages are required to be considered independently if possible in order to take advantage of modular approach. In order to suppress disturbance from the coarse to fine stage, they are designed without mechanical connections. Dual-servo tracking controller is applied by adding fine controller to conventional coarse controller. Reaction force between fine and coarse stages is compensated by a force compensator (FC) because it is detrimental to positioning and scanning. By simulation and experiment, the performance of dual-stage is evaluated and compared.

Laser Machining for Fabrication of Hohlraums and Capsules

Laser machining technology has been used to demonstrate the ability to rapidly perform jobs on all aspects of ICF targets. Lasers are able to rapidly perform modifications and repairs to the gold metal parts on hohlraums, make cuts in the delicate polymer parts of the hohlraum, and drill holes in the capsules to enable them to be filled with fuel. Lasers investigated in this work include 193 nm ArF and 248 nm KrF excimers and 810 nm chirped-pulse amplification Ti:Sapphire lasers. The excimer lasers showed a definite advantage in drilling and machining of polymeric materials and the ultrashort infrared pulses of the Ti:Sapphire laser were far better for the gold structures.

Metallic micro displacement capacitive sensor fabricated by laser micromachining technology

This paper presents design, fabrication and performance testing results of the micro displacement capacitive microsensor fabricated by femtosecond laser machining technology. The microsensor having overall dimensions of 1,275 (W)×1,153 (L) μm consisted of 20 pairs of comb fingers of 24 (W)×300 (L) μm with a gap between the fingers of 6 μm, suspension springs, inertial mass and support anchors. The sensor structure was fabricated from a 25 μm thick tungsten foil. The fabricated microsensor was able to deliver 230 fF capacitance variations for measured displacements up to 25 μm. The results on the performance testing and geometry evaluation under pins the laser micromachining technology as an effective tool to fabricate miniature functional components and mechanisms. The developed microsensor can be used for micro/nano scale displacement measurements in MEMS applications.

A cost-effective solution for packaging the arrayed waveguide grating (AWG) photonic components

Precision laser machining technology was used to cut arrayed waveguide grating (AWG) devices from 6-in wafers by following their complex profiles in a fully automatic way. A substantial cost saving in components manufacturing was achieved by an obtained device-cutting yield of 100%. The profile-cut AWG devices have smooth cutting edges and their optical performances were found unaffected by the cutting. These devices were processed in the subsequent packaging process easily without adding cost. They were proven mechanically stable in their packaging in meeting the telecommunication standards even though they have irregular geometry.

Geometrical modeling of surface profile formation during laser ablation of materials

Recent advances in laser machining technology have made it possible to fabricate parts and features with high accuracy and precision, using high-powered, short-pulsed, Q-switched lasers. To determine the machining parameters to obtain the desired geometrical quality, an understanding of the relationship between the process parameters and the resulting surface profile is necessary. In the present study, we adopt a geometrical approach which, coupled with the material properties and machining process parameters, yields a method to determine the surface profile of the material ablated by a laser pulse. It is reasoned that the energy incident upon an infinitesimal area of the surface at a given time is transferred in the outward normal direction to the surface, and the volume of ablation, centered about the normal, is determined by the laser–material interaction and the process parameters. The direction and depth of ablation determine the modified surface profile an infinitesimal time later, yielding a nonlinear partial differential equation, which is then integrated starting with the initial known surface to determine the profile at an arbitrary time. Theoretical predictions and the experimental results are compared for a test case of metals. The agreement between the two is satisfactory indicating the adequacy of the approach.

Comparative study of jetting machining technologies over laser machining technology for cutting composite materials

There has been a great interest for improving the machining of composite materials in the aerospace and other industries. This paper focuses on the comparative study of jetting techniques and laser machining technics. This paper concentrates on the machining of composite materials like epoxy pre-impregnated graphite woven fabric and fibre reinforced plastic materials that are used in aerospace industries. While considering machining these materials with the traditional machining there are many disadvantages projected. One of these advantages is that all the traditional machining processes involve the dissipation of heat into the workpiece. This serious shortcoming has been dealt by the jetting technologies, which, contrary to the traditional machining, operate under cold conditions. The two methods in the jetting technologies used for processing materials are water jet machining and abrasive water jet machining. The first of these, water jet machining, has been around for the past 20 years and has paved the way for abrasive water jet technology. Water jet machining and abrasive water jet machining have been used for processing composite materials because of the advantages offered by this technologies as compared to traditional techniques of processing. The high surface and structural integrity required of any technique used for processing composite materials has created an opportunity for abrasive water jet machining. Cutting of composites using laser is also an option, and experiments were also conducted to reveal the extent of using laser technique.

The development of a laser machining curriculum: An interdisciplinary approach (the MAST program)

The development of an industry‐driven interdisciplinary curriculum in laser machining is presented. The Machine tool Advance Skills Technology (MAST) program is a US Department of Education grant to develop and demonstrate a national training model for new technologies and manufacturing processes in precision manufacturing. Springfield Technical Community College (STCC) in partnership with six other community colleges nationwide, developed, tested, and disseminated industry‐specific skills standards and model curricula in laser machining and related technologies for the United States machine tool industry. STCC, with its strengths in laser and manufacturing engineering technologies, was selected to develop a true interdisciplinary program in laser machining by integrating key components from its laser electro‐optics technology (LEOT) and mechanical engineering technology (MET) programs.

Model of a laser heated plasma interacting with walls arising in laser keyhole welding.

In laser welding with laser intensities of approximately ${10}^{11}$ W/${\mathrm{m}}^{2}$, a hole, called a keyhole, is formed in the material. In this keyhole a plasma is detected, which is characterized by high pressure as well as being influenced by the boundary of the keyhole. Experimental data on plasma parameters are rare and difficult to obtain [W. Sokolowski, G. Herziger, and E. Beyer, in High Power Lasers and Laser Machining Technology, edited by A. Quenzer, SPIE Proc. Vol. 1132 (SPIE, Bellingham, WA, 1989), pp. 288--295]. In a previous paper [C. Tix and G. Simon, J. Phys. D 26, 2066 (1993)] we considered just a simple plasma model without excited states and with constant ion--neutral-atom temperature. Therefore we neglected radiative transport of excitations and underestimated the ion--neutral-atom temperature and the ionization rate. Here we extend our previous model for a continuous ${\mathrm{CO}}_{2}$ laser and iron and take into account radiative transfer of excitations and a variable ion--neutral-atom temperature. We consider singly charged ions, electrons, and three excitation states of neutral atoms. The plasma is divided in plasma bulk, presheath, and sheath. The transport equations are solved with boundary conditions mainly determined through the appearance of walls. Some effort is made to clarify the energy transport mechanism from the laser beam into the material. Dependent on the incident laser power, the mean electron temperature and density are obtained to be 1.0--1.3 eV and 2.5\ifmmode\times\else\texttimes\fi{}${10}^{23}$--3\ifmmode\times\else\texttimes\fi{}${10}^{23}$ ${\mathrm{m}}^{\mathrm{\ensuremath{-}}3}$. Radiative transport of excitations does not contribute significantly to the energy transport.

Screen-printed ultramicroelectrode arrays for on-site stripping measurements of trace metals

The properties and advantages of mercury-coated screen-printed electrode arrays for on-site stripping analysis of trace metals are described. These disposable composite electrodes are fabricated by a combination of thick-film printing and laser machining technologies, and offer a stripping performance comparable with that of traditional stripping electrodes. Scanning electron microscopy illustrates the attractive microdisk and interelectrode dimensions, which offer a non-linear diffusional flux during long stripping experiments. The stripping performance is not compromised by placing non-deaerated/quiescent sample drops on the strip, as desired for field monitoring of trace metals. Various experimental variables have been optimized to yield low detection limits (e.g. 0.1 μg/l lead for 4 min deposition) and good precision (e.g. relative standard deviation of 4.7% for ten repetitive measurements). The applicability to assays of drinking water and wine is illustrated.

High power industrial laser and present status of development of laser technology in automated branches of industry abroad (survey)

Modern laser machining technology possesses truly unique capabilities. The high reliability of robotized laser facilities with computer control, the possibility of practical continuous around-the-clock work, precision accuracy, and very high speed of performance of various technological operations (cutting, welding, hole drilling, etc.) frequently ensure them noticeably superiority over other similar facilities in automated branches of industry. A survey of the present status of laser technology in developed industrial countries is compiled from the latest foreign periodicals and reflects the level of laser automated industry in 1987–1989. The tendencies of global development of industrial lasers and of laser technology in the nearest future are presented.