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.

Fuzzy TOPSIS-Based Selection of Laser Beam Micro-marking Process Parameters

Abstract: The process parameter selection in any machining process is one of the most challenging criteria for effective machining. Selection of an optimal parametric combination always results in efficient machining. In the current work, a fuzzy TOPSIS method for selection of optimal laser beam micro-marking process parameters, such as current, pulse frequency, and scanning speed, during laser beam marking on gallium nitride is adopted. Response surface methodology (central composite design) is adopted for the experimental design. The mark width, mark depth, and mark intensity are considered as the process responses. The mark width and mark depth are measured with the help of a precision optical microscope. Microscopic images are then treated using image processing software to calculate the mark intensity. A multi-criteria decision-making model is developed considering the effect of process parameters on process response for selection of optimal process parameter in the laser beam micro-marking process. The triangular fuzzy number is used to calculate the weight of each performance criteria, and the fuzzy TOPSIS hybrid approach is used for selection of optimal parametric combination. The results indicate that a small pulse frequency and high current and scanning speed lead to increase in mark intensity.

An approach to modelling evaporation pulsed laser drilling and its energy efficiency

Abstract: Laser drilling is a thermal process with relatively low energy efficiency since the material removal mechanism is mostly based either on melting or on vaporization. Aiming at the investigation of the laser drilling efficiency, a theoretical both analytical and numerical study of evaporation pulsed laser drilling is presented. The analysis is based on a linear approximation of the temperature profile and separates the process into three phases, those of the heating, the melting and the vaporization. Based on these models, the energy efficiency and its dependence on the process parameters have been investigated and selection of relevant process variable guidelines, towards improving energy efficiency, are given. Moreover, the physical mechanisms responsible for most of the energy losses are analysed and classified according to their importance.

Injection molding quality control by integrating weight feedback into a cascade closed‐loop control system

Abstract: Quality control plays a crucial role in injection molding control to meet stringent tolerance requirements and to facilitate automation. Previous work has tackled this challenging subject mainly through consistent machine operations or process variable control. In this paper, a direct quality feedback control system has been proposed and developed. The system has a cascade structure and combines both feedback and feedforward controls. An important quality index, namely, part weight, is measured in each molding cycle. The difference between this measurement and a quality target is used to adjust the mold separation at the process level. The mold separation is controlled via both a cycle-to-cycle mass-based switchover point and a within-cycle holding pressure control. Molding experiments have been conducted using different mold geometries and resins. Compared with the cavity pressure based control system currently used in industry, the control system in this study results in a significant improvement of both long-term and short-term consistencies in part quality. In addition, this direct quality feedback control has other benefits, such as 100% quality inspection and automatic process tuning. POLYM. ENG. SCI., 47:852–862, 2007. © 2007 Society of Plastics Engineers