Fluid dispensing is a process used to deliver fluid materials to targets such as substrates, boards, or work-pieces in a controlled manner. This process has been widely used in electronic packaging industry for such processes as integrated circuit encapsulation (ICE) and surface mount technology (SMT). The most important parameters needed to be controlled in this process are the flow rate of fluid dispensed and the profile of fluid formed on a target. The modeling and control of such a process involves different engineering disciplines including mechanical, control, software/hardware, and material sciences. <p>The present research is aimed to carry out a comprehensive study on the modeling of the rotary-screw dispensing system, in which a motor-driven screw is used to deliver fluid materials. At first, characterization of the flow behavior of fluids used in the electronic packaging industry is addressed. Under the assumption that the pressure applied to feed the fluid material has reached its steady state value, a steady state model is then developed to represent the flow rate of fluid dispensed in the rotary-screw dispensing process. On this basis, by taking into account the fluid compressibility and the fluid inertia, a dynamic model is developed to represent the dynamics of the flow rate, which is critical if the amount of fluid required to dispense is very small. <p> Experiments conducted on a typical commercial dispensing system of DS-500 (provided by Assembly Automation Limited, Hong Kong) were used to characterize the flow behavior of the fluid dispensed based on the model developed. The method of identifying the flow behavior from dispensing experiments, rather than a rheometer, allowed us to eliminate the massive measurements needed in the use of rheometer. <p>To validate the steady state model, simulations were carried out in Matlab and the results were then compared with the experimental results obtained. It is shown that the simulation results are in close agreement with the experimental results. Based on the dynamic model developed in this study, simulations were carried out to investigate the effects of operational parameters, such as temperature and fluid properties, on the flow rate of the fluid dispensed. In addition, the inconsistency in the fluid amount dispensed was also investigated by using the dynamical model. It has been shown that for dispensing small amounts of fluid, the dynamics of the flow rate dominates the process and that in this situation, the amount dispensed can be predicted by using the dynamic model developed and, in contrast, the use of the steady state model, which is commonly adopted in industry, can result in a large error in the model prediction. <p>Based on the dynamic model, a new approach is developed to integrate the model into the design of fluid dispensing system. This approach could be used not only to evaluate the existing dispensing systems, but also to design new dispensing systems.

Fluid dispensing is a process used to deliver fluid materials to targets such as substrates, boards, or work-pieces in a controlled manner. This process has been widely used in electronic packaging industry for such processes as integrated circuit encapsulation (ICE) and surface mount technology (SMT). The most important parameters needed to be controlled in this process are the flow rate of fluid dispensed and the profile of fluid formed on a target. The modeling and control of such a process involves different engineering disciplines including mechanical, control, software/hardware, and material sciences. <p>The present research is aimed to carry out a comprehensive study on the modeling of the rotary-screw dispensing system, in which a motor-driven screw is used to deliver fluid materials. At first, characterization of the flow behavior of fluids used in the electronic packaging industry is addressed. Under the assumption that the pressure applied to feed the fluid material has reached its steady state value, a steady state model is then developed to represent the flow rate of fluid dispensed in the rotary-screw dispensing process. On this basis, by taking into account the fluid compressibility and the fluid inertia, a dynamic model is developed to represent the dynamics of the flow rate, which is critical if the amount of fluid required to dispense is very small. <p> Experiments conducted on a typical commercial dispensing system of DS-500 (provided by Assembly Automation Limited, Hong Kong) were used to characterize the flow behavior of the fluid dispensed based on the model developed. The method of identifying the flow behavior from dispensing experiments, rather than a rheometer, allowed us to eliminate the massive measurements needed in the use of rheometer. <p>To validate the steady state model, simulations were carried out in Matlab and the results were then compared with the experimental results obtained. It is shown that the simulation results are in close agreement with the experimental results. Based on the dynamic model developed in this study, simulations were carried out to investigate the effects of operational parameters, such as temperature and fluid properties, on the flow rate of the fluid dispensed. In addition, the inconsistency in the fluid amount dispensed was also investigated by using the dynamical model. It has been shown that for dispensing small amounts of fluid, the dynamics of the flow rate dominates the process and that in this situation, the amount dispensed can be predicted by using the dynamic model developed and, in contrast, the use of the steady state model, which is commonly adopted in industry, can result in a large error in the model prediction. <p>Based on the dynamic model, a new approach is developed to integrate the model into the design of fluid dispensing system. This approach could be used not only to evaluate the existing dispensing systems, but also to design new dispensing systems.

The deflections of screw rotors under machining forces cause mismatch between the male and female rotors and, consequently, accelerated wear and suboptimal efficiency in their performance. Optimizing the machining process to minimize the generated forces and accounting for the resulting mismatch in the design of the rotor profile requires accurately computing the machining forces in computer simulations. Virtual machining systems combine graphics-based computation of the Cutter-Workpiece Engagement (CWE) with the physics-based models of machining mechanics to simulate the forces during complex machining processes. However, because of the high computational load of graphical simulations, virtual machining is not suitable for the repetitive force simulations that are required for optimizing the design and manufacturing of rotors. In this work, we present a new method that simulates screw milling forces based on the process kinematics instead of graphical simulations. Utilizing mathematical equations that describe the process kinematics, the theoretical rotor profile is determined for feasible combinations of cutting tool profile, setup angle, and centre distance. Subsequently, to find the milling forces, the cutting edge is discretized into multiple small edge segments and a mechanistic cutting force model is used to determine the local cutting forces at each segment. After geometric and kinematic transformations of these local forces, the screw milling forces are obtained for each roughing and finishing pass. Instead of graphics-based methods, the engagement conditions between the cutter and workpiece are determined by the ensemble of 2D rotor and tool profiles; as a result, the computational efficiency is increased substantially. The semi-analytical nature of the presented method allows for computing the forces with arbitrary resolution within a reasonable time. The accuracy and efficiency of the presented method is verified by comparing the simulated forces against a dexel-based virtual machining system. / Graduate

<div>The purpose of this research is to analyze the overall energy consumption of an industrial compressed air system, and identify the impact of various energy saving of individual subsystem on the overall system. Two parameters are introduced for energy consumption evaluation and potential energy saving: energy efficiency (e) and process effectiveness (n). An analytical energy model for air compression of the overall system was created taking into consideration the modeling of individual sub-system components: air compressor, after-cooler, filter, dryer and receiver. The analytical energy model for each subsystem included energy consumption evolution using the</div><div>theoretical thermodynamic approach. Furthermore, pressure loss models of individual components along with pipe friction loss were included in the system overall efficiency calculation.</div><div>The efficiency analysis methods and effectiveness approach discussed in this study were used to optimize energy consumption and quantify energy savings. The method</div><div>was tested through a case study on a plant of a die-casting manufacturing company. The experimental system efficiency was 76.2% vs. 89.3% theoretical efficiency. This showed model uncertainty at ~15%. The effectiveness of reducing the set pressure increases as the difference in pressure increase. The effectiveness of using outside air for</div><div>compressors intake is close to the compressors work reduction percentage. However, it becomes more effective when the temperature difference increase. This is mainly due to extra heat loss. There is potential room of improvement of the various component using the efficiency and effectiveness methods. These components include compressor, intercooler and dryer. Temperature is a crucial parameter that determines the energy consumption applied by these components. If optimum temperature can be determined, plenty of energy savings will be realized.</div>