Process variable

About: Process variable is a research topic. Over the lifetime, 3983 publications have been published within this topic receiving 43130 citations. The topic is also known as: process parameter.

Pulsed Nd:YAG laser turning of micro-groove on aluminum oxide ceramic (Al2O3)

Abstract: The present study investigates the relationship of processes parameters of pulsed Nd:YAG laser-turning operation for production of micro-groove on cylindrical workpiece of ceramic material. A microprocessor-based work holding device has been developed to provide the rotational motion of cylindrical work pieces for micro-turning operation. Laser turning of micro-grooves on ceramics is highly demanded in the present industry because of its wide and potential uses in various fields such as automobile, aerospace and bio-medical engineering applications, etc. Experiments have been conducted on laser micro-grooving of aluminum oxide (Al2O3). The central composite second-order rotatable design (CCD) had been utilized to plan the experiments and response surface methodology was employed for developing empirical models. Analysis on machining characteristics of pulsed Nd:YAG laser micro-grooving operation was made based on the developed models. In this study, lamp current, pulse frequency, pulse width, assist air pressure and cutting speed of work piece are considered as laser machining process parameters. The process performances such as upper deviation (Yuw), lower deviation (Ylw) and depth (Yd) characteristics of laser-turned micro-grooves produced on cylindrical work piece made of Al2O3 were evaluated. Analysis of variance (ANOVA) test had also been carried out to check the adequacy of the developed regression empirical models. The observed optimal process parameter settings are lamp current of 22.517 A, pulse frequency of 1.477 kHz, pulse width of 2.394% of duty cycle, cutting speed of 10.4283 rpm and assist air pressure of 1.3 kgf/cm2 for achieving minimum upper deviation, lower deviation and depth of laser-turned micro-grooves, and finally the results were experimentally verified. From the analysis, it was found that proper control of the process parameters lead to achieve minimum upper deviation, lower deviation and depth of laser-turned micro-grooves produced on cylindrical workpiece of Al2O3.

Method to determine the value of process parameters based on scatterometry data

Abstract: A method according to an embodiment includes obtaining calibration measurement data, with an optical detection apparatus, from a plurality of marker structure sets provided on a calibration substrate. Each marker structure set includes at least one calibration marker structure created using different known values of the process parameter. The method includes obtaining measurement data, with the optical detection apparatus, from at least one marker structure provided on a substrate and exposed using an unknown value of the process parameter; and determining the unknown value of the process parameter from the obtained measurement data by employing regression coefficients in a model based on the known values of the process parameter and the calibration measurement data.

On Process Temperature in Powder-Bed Electron Beam Additive Manufacturing: Process Parameter Effects

Abstract: Build part certification has been one of the primary roadblocks for effective usage and broader applications of metal additive manufacturing (AM) technologies including powder-bed electron beam additive manufacturing (EBAM). Process sensitivity to operating parameters, among others such as powder stock variations, is one major source of property scattering in EBAM parts. Thus, it is important to establish quantitative relations between the process parameters and process thermal characteristics that are closely correlated with the AM part properties. In this study, the experimental techniques, fabrications, and temperature measurements, developed in recent work (Cheng et al., 2014, "On Process Temperature in Powder-Bed Electron Beam Additive Manufacturing: Model Development and Experimental Validation," ASME J. Manuf. Sci. Eng., (in press)) were applied to investigate the process parameter effects on the thermal characteristics in EBAM with Ti-6Al-4 V powder, using the system-specific setting called “speed function (SF)” index that controls the beam speed and the beam current during a build. EBAM parts were fabricated using different levels of SF index (20–65) and examined in the part surface morphology and microstructures. In addition, process temperatures were measured by near infrared (NIR) thermography with further analysis of the temperature profiles and the melt pool size. The thermal model, also developed in recent work, was further employed for EBAM temperature predictions, and then compared with the experimental results. The major results are summarized as follows. SF index noticeably affects the thermal characteristics in EBAM, e.g., a melt pool length of 1.72 mm and 1.26 mm for SF20 and SF65, respectively, at 24.43 mm build height. SF setting also strongly affects the EBAM part quality including the surface morphology, surface roughness and part microstructures. In general, a higher SF index tends to produce parts of rougher surfaces with more pore features and large β grain columnar widths. Increasing the beam speed will reduce the peak temperatures, also reduce the melt pool sizes. Simulations conducted to evaluate the beam speed effects are in reasonable agreement compared to the experimental measurements in temperatures and melt pools sizes. However, the results of a lower SF case, SF20, show larger differences between the simulations and the experiments, about 58% for the melt pool size. Moreover, the higher the beam current, the higher the peak process temperatures, also the larger the melt pool. On the other hand, increasing the beam diameter monotonically decreases the peak temperature and the melt pool length.

Process parameter optimization during EDM of AISI 316 LN stainless steel by using fuzzy based multi-objective PSO

Abstract: The present contribution describes an application of a hybrid approach using fuzzy logic and particle swarm optimization (PSO) for optimizing the process parameters in the electric discharge machining (EDM) of AISI 316LN Stainless Steel. In this study, each experimentation was performed under different machining conditions of pulse current, pulse on-time, and pulse off-time. Machining performances such as MRR and EWR were evaluated. A Taguchi L9 orthogonal array was produced to plan the experimentation and the regression method was applied to model the relationship between the input factors and responses. A fuzzy model was employed to provide a fitness function to PSO by unifying the multiple responses. Finally, PSO was used to predict the optimal process parametric settings for the multi-performance optimization of the EDM operation. The experimental results confirm the feasibility of the strategy and are in good agreement with the predicted results over a wide range of machining conditions employed in the process.

A study to estimate the tensile strength of friction stir welded AA 5059 aluminium alloy joints

Abstract: Friction stir welding (FSW) is an important welding technique where in, and optimizing the process parameters will improve the joint strength of the welds. The FSW process and tool parameters play a major role in determining the joint strength. In this paper, an attempt has been made to establish an empirical relationship between the FSW process parameters (rotational speed, welding speed, and axial force) and predicting the maximum tensile strength of the joint. Statistical tools such as design of experiments, analysis of variance, and regression analysis are used to develop the relationships. A non-heat treatable aluminum alloy Aluminium Association 5059 of 4 mm thickness was used as the base material. Response surface methodology is employed to develop the mathematical model. Analysis of variance technique is used to check the adequacy of the developed mathematical model. The developed mathematical model can be used effectively at 95 % confidence level. The effect of FSW process parameter on mechanical property of Aluminium Association 5059 aluminum alloy has also been analyzed in detail.