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During laser cleaving of brittle materials, with the controlled fracture technique, thermal stresses are generated which induce the crack and extend it along the cutting path, subsequently causing material separation. One of the problems in laser cutting of glass with this technique is the cut path deviation at the leading and the trailing edges of the glass sheet. Previous work with a continuous beam diode laser has shown the deviation to be partly due the high magnitudes of thermal stresses generated near the edges of the sheet. This paper reports on the effects of using a pulsed diode laser to cut soda lime glass. The effect of pulse parameters and cutting speed on the quality output variables such as cut deviation angle and surface finish are studied. Finite element modelling is also used to simulate the effects of the moving beam on stress generations to facilitate the understanding of the process mechanisms, and the results are compared with the experimental data. This work shows how to minimise the cut path deviation at the edges by reducing thermal stresses using optimum pulsed diode laser parameters and providing additional flexibility to the process. [ABSTRACT FROM AUTHOR]

This paper presents single and dual assist gas jet effects in the single-pass laser cutting of dry pine wood. The laser wood cutting process is influenced by the assisting gas jet(s) applied. Therefore, it is important to understand their roles in the removal of fumes and combusted materials from the cutting kerf. A computational fluid dynamic model is developed to investigate the effect of single and dual gas jets in the laser wood cutting process. In order to obtain a close approximation of the actual process, a three-dimensional model was considered. Results obtained in the simulations were compared with experimental data collected from a multifactor experiment analysing the laser cutting process of dry pine wood. A high brightness, 1 kW IPG single-mode, continuous-wave Ytterbium fibre laser was employed to cut cubic wood samples parallel to the wood fibre direction. It has been found that shear stresses produced by the gas jet(s) on the kerf walls have an important correlation with the yield and cut quality. [ABSTRACT FROM AUTHOR]

This paper presents a statistical analysis of the performance of an Ytterbium fibre laser utilising single and dual gas jets in a single pass to blind cut dry pine wood. Cutting wood with lasers is a multi-factor process and a proper combination of the parameters involved is needed to achieve high quality and optimum process efficiency. This study employs design of experiments and statistical modelling approach to investigate the significant process parameters along with their interactions. A high brightness, 1 kW IPG single mode Ytterbium-doped fibre laser was employed to produce blind cuts on samples of dry pine wood. The experiments were performed parallel to the direction of the wood fibre. The parameters investigated include laser power, focal plane position, traverse speed, gas pressure and single and dual gas jets. Results were compared using a number of process responses which define the efficiency of the cut in terms of kerf depth, mass removal and energy consumption as well as quality of the cut section considering the heat-affected zone, kerf width and roughness of the edge of the surface. It has been found that application of an additional gas jet produced a surface finish superior to the single jet. [ABSTRACT FROM AUTHOR]