Dentre as principais propriedades que devem ter os implantes ortopédicos, tem-se a resistência à corrosão. Os implantes passam por um processo de marcação antes de serem esterilizados, cuja função é prover a identificação e rastreabilidade do produto. Este trabalho teve o objetivo de avaliar o efeito de duas técnicas de marcação, mecânica e a laser, na resistência à corrosão do aço inoxidável austenítico ABNT NBR ISO 5832-1, um dos mais utilizados no Brasil na fabricação de próteses. Os ensaios eletroquímicos realizados constaram de monitoramento do potencial de corrosão em circuito aberto, espectroscopia de impedância eletroquímica, determinação das propriedades eletrônicas do filme passivo via abordagem de Mott-Schottky, medidas de polarização potenciodinâmica cíclica e a técnica eletroquímica de varredura com eletrodo vibrante (SVET), à temperatura de 37°C. O eletrólito utilizado foi uma solução salina de fosfato tamponada de pH 7,4. Foram realizadas análises por microscopia óptica, microscopia eletrônica de varredura, SEM-FEG e, microscopia eletrônica de transmissão. Constatou-se que a marcação a laser diminui a resistência à corrosão por pite ao alterar significativamente as características do filme passivo, quando comparada à marcação mecânica e ao material sem marcações. Foram observadas inclusões de óxidos que foram colocadas em relevo pela dupla incidência do feixe de laser. O ataque da matriz de aço no entorno das inclusões de óxidos promove a formação de micro-frestas entre esta e as inclusões favorecendo o crescimento e a propagação do pite. Este foi o mecanismo proposto para explicar a maior susceptibilidade à corrosão localizada nas áreas afetadas pela marcação a laser. / Among the most important properties that orthopedic implants should have, is the corrosion resistance. The implants undergo a process of marking before being sterilized, whose function is to provide identification and traceability. This study evaluated the effect of two marking techniques, mechanical and laser, on the corrosion resistance of austenitic ISO 5832-1 stainless steel, the most commonly used material in Brazil on the manufacture of implantable medical devices. The electrochemical tests performed consisted of monitoring the corrosion potential in open circuit, electrochemical impedance spectroscopy, determining the electronic properties of passive film via Mott-Schottky approach, and cyclic potentiodynamic polarization measurements and scanning vibrating electrode technique (SVET) at the temperature of 37 ° C. The electrolyte used was a naturally aerated phosphate buffered solution, pH 7,4. Analyzes were performed by optical microscopy, scanning electron microscopy, SEM-FEG, and transmission electron microscopy. The results indicated that the laser marking process increases the susceptibility to pitting corrosion by significantly altering the characteristics of the passive film, as compared to the material without marks and mechanically marked. Oxide inclusions were observed placed into relief by the double incidence of the laser beam. The attack of the steel matrix surrounding the inclusions of oxides promotes the formation of micro-crevices between this and the inclusions favoring the growth and propagation of pits. This was the mechanism proposed to explain the increased susceptibility to localized corrosion in areas affected by the laser marking process.

The “Development of an existing engraving machine by designing a protection cabin for laser marking”project consists of the achievement of a protection cabin for a marking laser by applying the theory and the experience acquired during the courses in Mechanical Engineering program. Degree project is made with the Maskinteknik i Oskharsham AB by the Mechanical Engineering student, Ahmet Azman and Sabra Meradi. This protection cabin is design for the Deckel GK 21 engraving machine that company already bought it several years ago. The safety requirements for laser protection cabin shown in IEC and ISO standard will be observed. The design process explained in the GETTING DESIGN RIGHT: A Systems Approach book will be followed to achieve this project. Six steps of this method are followed: Define the problem, Measure the needs and set targets, Explore the design space, Optimize design choices, Develop the architecture, Validate the project.

Characters on computer keyboards are typically printed using one of the two different processes, namely tampographic printing and laser marking. Tampographic printing is time consuming (app. 3-5 mins.), requires skilled workers and employs difficult-to-handle chemicals. On the other hand, the laser marking process is rapid «1 min.), relatively cheap, avoids the need for chemicals and can be carried out with fewer, less skilled operatives than required fortampographic printing. Data from a keyboard production company indicated that there has been a sudden decline in the percentage (from 60% in 2001 to less than 10% in 2003) of laser marked keyboard users over recent years due to a lack of initial contrast of white characters on a dark plastic and poor durability. Under usual office conditions, characters that are used more regularly e.g. 'e' or 's', can be erased in less than 3-6 months. Further, generating a durable high contrast laser mark on dark coloured polymers has also long been an issue. The thesis initially reports on an investigation into the reasons for lack of initial contrast and subsequent discolouration of laser marked and tampo printed characters. This is followed by the development of a range of plastics compounds based on ABS and containing a series of different additives. Criteria for selecting additives that would respond appropriately to a laser are also proposed. The compounds were laser marked under a 1064nm Nd:YAG laser at different power, frequency and speed settings. Plaques of the material were manufactured and laser marked in a grid-like pattern to study both the effect of frequency and speed of marking. The mechanisms associated with the laser-material interaction during the marking process were also investigated using light microscopy and scanning electron microscopy. Microscopy was also employed toobserve the morphology of the marks left by the laser. Finally a unique test regime was designed to characterise the durability of the laser markings under conditions that attempt to simulate those experienced in practice. Results show that aluminium trihydroxide generated superior contrast and exhibited enhanced durability characteristics when compared with nine other micro-additives. Nano-additives, such as nano titanium dioxide portrayed better contrast and durability performance when compared to their micro-size additive equivalents. Analysis of the test plaque results clearly demonstrated that for a specific material compound, it is possible to optimise the laser settings to achieve the best combination of character contrast and durability. Finally, this work is believed to have made a significant contribution to the rather sparse laser markable polymers research field. It will assist in the development of a more fundamental understanding of laser/material interactions and provide a basis for future work in optimising materials formulations for successful laser marking.

Dentre as principais propriedades que devem ter os implantes ortopédicos, tem-se a resistência à corrosão. Os implantes passam por um processo de marcação antes de serem esterilizados, cuja função é prover a identificação e rastreabilidade do produto. Este trabalho teve o objetivo de avaliar o efeito de duas técnicas de marcação, mecânica e a laser, na resistência à corrosão do aço inoxidável austenítico ABNT NBR ISO 5832-1, um dos mais utilizados no Brasil na fabricação de próteses. Os ensaios eletroquímicos realizados constaram de monitoramento do potencial de corrosão em circuito aberto, espectroscopia de impedância eletroquímica, determinação das propriedades eletrônicas do filme passivo via abordagem de Mott-Schottky, medidas de polarização potenciodinâmica cíclica e a técnica eletroquímica de varredura com eletrodo vibrante (SVET), à temperatura de 37°C. O eletrólito utilizado foi uma solução salina de fosfato tamponada de pH 7,4. Foram realizadas análises por microscopia óptica, microscopia eletrônica de varredura, SEM-FEG e, microscopia eletrônica de transmissão. Constatou-se que a marcação a laser diminui a resistência à corrosão por pite ao alterar significativamente as características do filme passivo, quando comparada à marcação mecânica e ao material sem marcações. Foram observadas inclusões de óxidos que foram colocadas em relevo pela dupla incidência do feixe de laser. O ataque da matriz de aço no entorno das inclusões de óxidos promove a formação de micro-frestas entre esta e as inclusões favorecendo o crescimento e a propagação do pite. Este foi o mecanismo proposto para explicar a maior susceptibilidade à corrosão localizada nas áreas afetadas pela marcação a laser. / Among the most important properties that orthopedic implants should have, is the corrosion resistance. The implants undergo a process of marking before being sterilized, whose function is to provide identification and traceability. This study evaluated the effect of two marking techniques, mechanical and laser, on the corrosion resistance of austenitic ISO 5832-1 stainless steel, the most commonly used material in Brazil on the manufacture of implantable medical devices. The electrochemical tests performed consisted of monitoring the corrosion potential in open circuit, electrochemical impedance spectroscopy, determining the electronic properties of passive film via Mott-Schottky approach, and cyclic potentiodynamic polarization measurements and scanning vibrating electrode technique (SVET) at the temperature of 37 ° C. The electrolyte used was a naturally aerated phosphate buffered solution, pH 7,4. Analyzes were performed by optical microscopy, scanning electron microscopy, SEM-FEG, and transmission electron microscopy. The results indicated that the laser marking process increases the susceptibility to pitting corrosion by significantly altering the characteristics of the passive film, as compared to the material without marks and mechanically marked. Oxide inclusions were observed placed into relief by the double incidence of the laser beam. The attack of the steel matrix surrounding the inclusions of oxides promotes the formation of micro-crevices between this and the inclusions favoring the growth and propagation of pits. This was the mechanism proposed to explain the increased susceptibility to localized corrosion in areas affected by the laser marking process.

Laser processing has the advantage of minimal sample contact and thus little tool wear over time compared to conventional machining. However, this leads to the difficulty of real-time depth monitoring and control. To help understand the process and achieve automation of laser micromachining, a coherent imaging technique adapted from spectral domain optical coherence tomography (SD-OCT) is applied “inline”with a machining laser to monitor the depth changing information. The axial resolution of the inline coherent imaging (ICI) system is 7–8 microns and the acquisition rate is up to 230 kHz. The capture time is as low as 1.5 microseconds. 3D laser machining usually requires ultrafast lasers and homogeneous materials. With ICI, a feedback system is developed for 3D sculpture suitable even for heterogeneous materials without any sophisticated material characterization. 3D patterns with sizes up to 1 mm × 1 mm × 0.2 mm are sculpted in bone and wood with a ps UV laser. 3D patterns with sizes up to 6 mm × 6 mm × 2 mm are sculpted in bone with a CW IR laser. Many laser applications require high scan speed facilitated by scanning optics. The versatility of ICI is also demonstrated in a galvo-telecentric beam delivery system. ICI is used in a process of trench (as long as 10 mm) etching of steel to monitor the intrapulse and interpulse morphology changes as well as the sweep-to-sweep (up to 36 sweeps) depth changes. High scan speed (up to 375 mm/s) trench etching of silicon are also monitored and the parameter space is explored without destructive post-processing. Motion during imaging capture time (>1.5 microseconds) may cause contrast degradation. To reduce the motion artifacts, preliminary experiments on stroboscopic ICI based on a kHz pulse repetition rate femtosecond laser are described. By “sampling” the motion of the machining front discretely with a “sampling time” as short as the imaging pulse duration, our results demonstrate that stroboscopic ICI is a promising way to improve the ICI contrast against motion artifacts. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2014-04-30 13:56:35.793

Le travail de thèse décrit plusieurs sources lasers originales spécifiquement développées pour deux applications particulières que sont la spectroscopie LIBS (Laser Induced Breakdown Spectroscopy) et le marquage de câbles par laser. Les travaux sur la LIBS ont eu pour principaux objectifs de proposer de nouvelles solutions pour rapprocher les performances de la LIBS portable de celles de la LIBS de laboratoire et d’évaluer leur potentiel sur des applications géologiques. De nouvelles solutions de spectromètres (technologie SWIFTS) et de lasers compacts ont ainsi été évaluées et ont conduit par exemple à la réalisation d’un nouveau pistolet d’analyse LIBS portable. Les deux sources laser disposent de performances spécifiques : une première source compacte de très bonne qualité de faisceau émettant à 532 nm permettant d'obtenir une forte résolution spatiale adaptée à de la cartographie chimique de surface et une deuxième source infrarouge d'encombrement minimum et de qualité de faisceau plus faible mais d'une grande robustesse. La source laser développée pour le marquage par balayage est donc un laser Nd:YVO4 impulsionnel, quelques watts moyens, émettant dans l’ultraviolet à 355 nm. L’architecture originale utilisée, le « Cavity-Dumped », permet d’obtenir une durée d’impulsion constante (2 ns) quelle que soit la fréquence de répétition et donc une puissance crête élevée même à cadence importante. La très bonne qualité de faisceau observée a aussi permis d’obtenir un spot laser de très faible diamètre compatible avec un marquage précis et bien contrasté. / This work describes three original laser sources developed specifically for Laser Induced Breakdown Spectroscopy (LIBS) and wire marking. The main goal of the work on the LIBS was to propose new solutions to make portable LIBS as efficient as laboratory LIBS and to evaluate their potential in geological applications. New spectrometers (based on SWIFTS technology) and compact lasers were evaluated and they led to the realization of a portable LIBS gun. The two types of analyze possible which are in situ analysis and chemical cartography of the sample surface led to design two specific lasers: a first compact source emitting at 532 nm with a high beam quality allowing a high spatial resolution and a second one with a lower beam quality but much more robust. The laser developed for marking is a Q-switched Nd:YVO4 emitting in the UV at 355 nm. The original architecture used, the “Cavity-Dumped”, make the pulse duration constant (2 ns) with any repetition rate so that the peak power is high even if the repetition rate is important. The very good beam quality observed makes the laser spot very small so that the marking is very precise and contrasted.

This diploma thesis is focused on the design of a robotic workstation for laser marking of aluminium hinges for the automotive industry. Robots remove wheel hinges from palettes at the end of a preassembly line, mark them a sort them. At first, selected marking technologies used in the automotive industry are introduced. Afterwards, a few robot and process simulation software are described. Subsequently, several layout variants are created as viable options for process handling and the chosen variant is designed in detail. Using RobotStudio software, a simulation of the robotic marking cell is made for process verification. Finally, a technical - economic evaluation is performed.

Ce mémoire présente des travaux portant sur le développement de trois sources lasers pompées longitudinalement par diodes laser et déclenchées activement par modulateur électro-optique pour deux applications spécifiques : la LIBS et le marquage par laser. Ces travaux ont été réalisés en collaboration avec deux sociétés : Bertin Technologies et SDAE.Le premier chapitre de ce manuscrit présente le développement d’une nouvelle source laser compacte, réalisée pour la société Bertin Technologies dans le cadre d’un projet de tri de matériaux plastiques par analyse spectroscopique de plasma induit par laser (LIBS). Cette technique d’analyse ponctuelle ainsi que le contexte spécifique du projet sont détaillés dans la première partie de ce chapitre. Ensuite, les différentes étapes de recherche et de développement qui ont permis d’aboutir à cette nouvelle source laser innovante, compacte et de hautes performances seront décrites en détail. Le second chapitre présente le développement de deux sources lasers pour le marquage industriel réalisées en partenariat avec la société SDAE. Après avoir présenté les principes et techniques généraux de l’application marquage ainsi que les contraintes spécifiques au projet, les deux sources lasers développées seront décrites. Des tests de LIBS et de marquage ont été réalisés grâce aux lasers développés / This thesis deals with the development of three lasers end-pumped by laser diode and actively Q-Switched by electro-optic Pockels cells for two specific applications: Laser Induced Breakdown Spectroscopy (LIBS) and marking. This work was done in collaboration with two companies: Bertin Technologies and SDAE.In the first part, we present the development of a new compact laser source, made for Bertin Technologies as part of sorting of plastics waste by LIBS. This analysis technique and the specific context of the project will be detailed in the first part of this chapter. Then, the different steps of research and development which have resulted in this innovative, compact and high performance new laser are described in detail. The second part is devoted to the development of lasers for industrial marking accomplished in partnership with SDAE. More precisely, the general principles and techniques of laser marking are described as well as the specific constraints of this project. LIBS and laser marking tests will be done with these lasers