Surface cleaning is an essential step within the manufacturing process that ensures and enhances the integrity of the final component. Conventional surface cleaning methods have various shortfalls leading to the need for a more controllable surface cleaning methods such as laser cleaning. By utilising the principle behind laser induced breakdown spectroscopy (LIBS), an economical inline monitoring system is implemented in a laser cleaning cell, to achieve a closed-loop laser coating removal from tungsten carbide substrate. Cutting tests were performed on the re-coated laser coating removed inserts showing similar performance as compared to the as-received coated inserts.
Laser drilling of monolithic materials like metals and alloys is a well-established process and used extensively in a wide range of applications in many sectors including aerospace, medical and automotive. However, conventional laser drilling of materials like metal matrix composites is challenging due to the differences in the chemical and physical properties of the hard ceramic reinforcement particles and the soft-metal matrix. The water-jet guided laser process has the potential to machine advanced materials such as an aluminium metal matrix composite reinforced with silicon carbide particles (Al MMC), with exceptional quality. The main objective of this research is to understand the material removal mechanism associated with water-jet guided laser drilling of Al MMCs and compare this with conventional laser drilling of Al MMC. Experimental results showed that the water-jet guided laser process is an excellent technique for drilling holes in composite materials like metal matrix composites. During water-jet guided laser drilling of Al MMC, the material has been removed by cold ablation, without leaving any residual melt layer within the bulk material. Both soft-matrix and hard-particles are removed by the same process of cold ablation, which is completely different to the conventional laser drilling process in which the solid SiC are ejected without melting, along with the molten aluminium.
EDM and laser processing are extensively used for drilling cooling holes in various aero and land based turbine components, including combustion casing, vanes and blades. However, as it is envisaged that future generation of aero engines will typically have in excess of 150,000 cooling holes, which will result in enormous pressure on technology providers to meet some very challenging targets in relations to productivity and hole quality. This represents a significant R&D opportunity to improve the performance of current hole drilling process to keep up with the ever increasing customer demands. This paper investigates high speed hole drilling (0.8 mm diameter) of nickel based aerospace alloy (5-10 mm thick) with the state-of-the-art EDM and laser drilling machines. EDM trials were performed using GF Agie Charmilles, 7-axis Drill 300 unit and laser trials were performed using a DMG LT50 PowerDrill unit equipped with an IPG 20 kW QCW fibre laser sources. A 2-level 3-factor full factorial design was used to identify the preferred operating parameters for each process. The main investigation concentrates on identifying suitable hole drilling regimes for EDM and laser drilling process on basis of drilling speed, recast layer thickness and hole taper. Results showed a step change in drilling speed (4-5 folds) compared to previous generations of EDM and laser machines (ND:YAG laser and standard EDM drill), with significant enhancement in hole quality and integrity. EDM showed significantly better results with regards to recast layer (10-15 μm compared to ∼80 μm for laser) and geometric accuracy / taper particularly for thicker samples. Laser drilling, however, was far superior in terms of speed with <3s drilling time for 10 mm thick samples compared to 48s best recorded EDM drilling time.
Laser drilling of metals and alloys is extensively used in modern manufacturing industries to produce holes of various sizes and shapes. Currently, most aerospace laser drilling is performed using Nd:YAG laser and over the years many attempts have been made to increase the productivity of Nd:YAG lasers drilling process, but with little success. This paper investigates the use of recently developed millisecond-pulsed-Quasi-CW- fibre-laser for trepanning drilling of aerospace grade nickel super-alloy. The main investigation concentrates on understanding the effects of Quasi-CW-fibre-laser parameters on trepanning laser drilled hole quality. The principal findings are based on reducing the recast and oxide layer. Results show that the high average power of the Quasi-CW-fibre-lasers can be effectively used to achieve increased trepanning drilling speed without undermining the drilling quality, which is not feasible with a free-space Nd:YAG laser. Low peak power and high average power can be effectively used to produce better laser drilled hole than the high peak power and low frequency, which is observed with the traditional millisecond Nd:YAG drilling process.
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