Papers by Keyword: Nd:YAG Laser

Abstract: Micro milling of super alloy materials such as nickel based alloys such as Inconel 718 is challenging due to the excellent of its mechanical properties. Therefore, new techniques have been suggested to enhance the machinability of nickel based alloys by pre-heating the workpiece’s surface to reduce its strength and ductility. The prediction of fluctuated temperature distribution generated by pulsed wave laser in laser assisted micro milling (LAMM) is crucial. The selection of processing parameter by minimize the effect on the processing characteristic is decisive to ensure the machining quality is high. Determining the effect of heat generated in underneath surface is important to make sure that the cutting tools are able to cut the material with maximum depth of cut and minimum defects in terms of tool wear and tool life. In this study the simulation was carried by using Ansys APDL. In order to confirm the actual and distribution irradiation of temperature from simulation, an experimental was done to validate the results. The experiment was conducted by using Nd:YAG laser with wavelength 1064 nm.

Abstract: Shape memory alloy (SMA) is an intermetallic compound able to recover, in a predetermined shape during a thermal cycle while generating mechanical work. The primary objective of this research is to develop a shape memory alloy based micro-positioning stage. This paper reports about the training, actuation method of NiTi shape Memory alloy thin sheets and its displacement measurement through Michelson Interferometer. The SMA based Tripod was fabricated the actuation was done using an electrical biasing with 5 A(1.2 Volt) where a displacement of around 6.10 mm was achieved. The actuation studies were also performed using a laser with a optimum fluence of 100 mJ/cm² that is of upto7.25 mm achieved.

Abstract: This paper presents laser surface modification of gray cast iron for enhanced surface hardness properties. A 300 W high power Nd:YAG laser system with pulse mode was used to modify gray cast iron samples surface. Laser processing was conducted using a 3³ full factorial design. Three controlled parameters were laser power, pulse duration and overlap percentage. The modified surface was characterised for metallographic study, roughness and hardness. Metallographic study and surface morphology were conducted using optical microscope while hardness properties were measured using Vickers scale. Surface roughness was measured using a 2D stylus profilometer. The results show that hardness of laser modified surface increased due to grain refinement. The overlapping rates increased significantly with decreasing laser scanning speed which affected sample surface integrity. Low surface roughness obtained at the highest scanning speed of 1400 mm/min, and low power of 830 W with pulse repetition frequency of 50 Hz. Process optimization was carried out for maximum surface hardness and laser modified depth, and minimum surface roughness. These findings indicate potential application of cast iron for high wear resistant applications through laser surface modification.

Abstract: Laser direct-part marking is finding increasing use in the tracking of products as they pass through a manufacturing process. But too high heat input of the laser may cause deformation of the product beyond the limit of the drawing. In order to investigate the effect of laser marked Data Matrix symbol on titanium alloy, a Q-switched lamp pumped Nd:YAG laser was used in this research. Two Data Matrix symbols using 16A and 28A of electric current were marked respectively in the center of two titanium alloy sheets with 50mm length and 50mm width and 2mm thickness. To analyze the quality of the laser marking, environmental scanning electron microscope (ESEM) and X-ray diffractometer (XRD) were used. Experimental results showed the HAN’S Q-switched lamp pumped Nd:YAG laser marking system did not cause damage to the titanium alloy.

Abstract: To establish a mathematical relationship between Nd:YAG laser parameters and the qualities of laser direct marked Data Matrix symbols on titanium alloys, multiple linear regression analyses were performed based on orthogonal experiment results. According to the analysis results, the paper developed a prediction model to estimate the contrasts of laser direct marked Data Matrix symbols (i.e. Symbol Contrast). The prediction model was statistically analyzed by regression analysis and multi-factor analysis of variance (ANOVA). The predicted symbol contrasts were compared with the experimental values and they were close. The multiple linear regression analyses results showed that the developed prediction model was extremely significant and could be used to estimate the symbol contrast in laser direct part marking.

Abstract: Threshold fluence (F_T), absorption coefficient (α) and thermal loading (γ) were estimated on three types of car coated substrate by applying Beer-Lambert law. Cynosure Cynergy Pulse Nd:YAG was using to irradiate 54 substrate samples and the depth of coating removed (d) was obtained by using Alicona IFM G4. Depth of coating removed (d) versus laser fluence (F) graphs was plotted for each pulse width (PW), repetition rate (RR) and beam size (BS) considered by measuring the average of coating removal efficiency (ε). The best interceptions of certains ε with their X-axis were selected for each sample A, B and C, representing their general F_T, α and γ respectively.

Abstract: To determine the impact of laser parameters on the contrasts of laser direct marked Data Matrix symbols on titanium alloys, a Q-switched Nd:YAG laser was used in the marking process. For this purpose, four laser marking parameters (i.e. electric current, effective vector step, Q-switch frequency, and laser line spacing) were correlated with the symbol contrast (SC). The L25 orthogonal array based on the Taguchi experimental method was adopted to determine the optimal combination levels of laser parameters for the SC, and the experimental data were statistically analyzed by multi-factor analysis of variance (ANOVA). Experimental results showed that the electric current, effectie vector step, laser line spacing have a statistically significant impact on the contrasts of laser marked Data Matrix symbols. Q-switch frequency is statistically insignificant at a 5% level. The optimal combination levels of laser parameters for the SC is where the electric current is at 26A, the effective vector step is at 0.001mm, the laser line spacing is at 0.01mm, and Q-switch frequency is at 5kHz.

Abstract: To identify critical laser marking parameters which have a statistically significant effect on the contrasts of laser marked Data Matrix symbols on titanium alloy substrates, a Q-switched Nd:YAG laser was used in the laser marking process. The influence of six laser marking parameters (i.e. electric current, effective vector step, delay between the effective vector step, Q-switch frequency, Q release time, and laser line spacing) on the contrasts of laser marked Data Matrix symbols were studied. Single-factor analysis of variance(ANOVA) tests with a 95% confidence level were employed to determine whether a laser parameter had a statistically significant impact on the contrasts of laser marked Data Matrix symbols. Experimental results showed that four laser marking parameters (i.e. electric current, effective vector step, Q-switch frequency, and laser line spacing) have a statistically significant effect on the contrasts of laser marked Data Matrix symbols.

Abstract: The prediction of fluctuated temperature distribution generated by pulsed wave laser in laser assisted micro milling (LAMM) is crucial. The selection of processing parameter by minimize the effect on the processing characteristic is decisive to ensure the machining quality is high. Determining the effect of heat generated in underneath surface is important to make sure that the cutting tools are able to cut the material with maximum depth of cut and minimum defects in term of tool wear and tool life. In this study the simulation was carried by using Ansys APDL. In order to confirm the actual and distribution irradiation of temperature from simulation, an experimental was done to validate the results. The experiment was conducted by using Nd:YAG laser with wavelength 1064 nm.

Abstract: Welding parameters are directly influenced by the work material properties. Thermal properties such as thermal conductivity and melting point are very important to estimate the range of power required and the allowable scanning speed. However, when two or more different materials are involved, modifying lasing parameters are not enough to counter the problems such as imbalance melting region and weak adhesion of contact surface. To counter this problem, the characteristics of welding beads formation for both materials need to be clarified. In this study, comparison of welding beads constructed using the same scanning parameters were done to understand the different and similarity of melted region for the both materials. Actual welding of the both materials were done under different offset distance to obtain a balanced melting area and well mixed melting region.