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.

This thesis covers a systematic examination of wet granulation in a twin screw extruder. Granulation of the excipient, (alpha)-lactose monohydrate, was done with the aid of PVP in an aqueous solution which acted as a binding agent. The influences on agglomeration by the following processing parameters were studied: screw elements design, screw rotational speed, binding solution concentration, and binder addition method. Qualitative efforts had also been made in modeling the process to gain valuable insight into how the elements affected agglomeration and granule rupture. A commercial software package PFC^2D, based on the Discrete Element Method (DEM), was used to simulate the dynamic behavior of the screw elements in the barrel. Within the optimal range of 7.5 -10wt% binder concentration, all the screw profiles were studied for their capacity to produce desirable granules suited to solid oral dosage form production. By increasing the rotational speed from 30 RPM to 80 RPM, the granules size of the conveying, discharging and chopping elements decreased whereas this operating parameter had little effect on granule size within kneading blocks. The nominal particle size produced by a screw element increased from 300(mu)m to 1mm when dispersive mixing was its dominant purpose (i.e. the kneading block), thereby meeting our criteria for a suitable granule in tab letting. Similar size development of the granules was not found with the other conveying or distributive mixing elements. In regards to particle shape, the kneading blocks produced elongated shape granules while other elements tested in this study produced smaller, more spherical agglomerates. Either shape was found effective in tabletting. Wet granulation was not feasible with more extreme concentrations of the aqueous binder (i.e. 5 wt% or 12 wt%) in this project, and the hand pre-blend method was the only approach found suitable for metering this additive into the system while maintaining steady feeding rates and output. / Thesis / Master of Applied Science (MASc)

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Multiphase pumping with twin-screw pumps is a relatively new technology that has been proven successful in a variety of field applications. By using these pumps to add energy to the combined gas and liquid wellstream with minimal separation, operators have been able to reduce capital costs while increasing overall production. In many cases, such as subsea operations, multiphase pumping is the only viable option to make remote wells economic. Despite their many advantages, some problems have been encountered when operating under conditions with high gas volume fractions (GVF). Twin-screw multiphase pumps experience a severe decrease in efficiency when operating under wet-gas conditions, GVF over 95%. Field operations have revealed severe vibration and thermal issues which can lead to damage of the pump internals, requiring expensive maintenance. The research presented in this thesis seeks to investigate two novel methods of improving the performance of twin-screw pumps under wet-gas conditions. The first involves increasing the viscosity of the liquid stream. We propose that by increasing the viscosity of the liquid phase, the pump throughput can be increased. Tests were conducted at high GVF using guar gel to increase the viscosity of the liquid phase. Along with results from a multiphase pump model the pump behavior under wet-gas conditions with increased liquid viscosity was evaluated. The experimental results indicate that at high GVF, viscosity is not a dominant parameter for determining pump performance. Possible reasons for this behavior were proposed. These results were not predicted by current pump models. Therefore, several suggestions for improving the model’s predictive performance were suggested. The second method is the direct injection of liquid into the pump casing. By selectively injecting liquid into specific pump chambers, it is believed that many of the vibration issues can be eliminated with the added benefit of additional pressure boosting capacity. Since this method requires extensive mechanical modifications to an existing pump, it was studied only analytically. Calculations were carried out that show that through-casing liquid injection is feasible. More favorable pressure profiles and increased boosting ability were demonstrated.

Multiphase pumping with twin-screw pumps is a relatively new technology that has been proven successful in a variety of field applications. By using these pumps to add energy to the combined gas and liquid wellstream with minimal separation, operators have been able to reduce capital costs while increasing overall production. In many cases, such as subsea operations, multiphase pumping is the only viable option to make remote wells economic. Despite their many advantages, some problems have been encountered when operating under conditions with high gas volume fractions (GVF). Twin-screw multiphase pumps experience a severe decrease in efficiency when operating under wet-gas conditions, GVF over 95%. Field operations have revealed severe vibration and thermal issues which can lead to damage of the pump internals, requiring expensive maintenance. The research presented in this thesis seeks to investigate two novel methods of improving the performance of twin-screw pumps under wet-gas conditions. The first involves increasing the viscosity of the liquid stream. We propose that by increasing the viscosity of the liquid phase, the pump throughput can be increased. Tests were conducted at high GVF using guar gel to increase the viscosity of the liquid phase. Along with results from a multiphase pump model the pump behavior under wet-gas conditions with increased liquid viscosity was evaluated. The experimental results indicate that at high GVF, viscosity is not a dominant parameter for determining pump performance. Possible reasons for this behavior were proposed. These results were not predicted by current pump models. Therefore, several suggestions for improving the model’s predictive performance were suggested. The second method is the direct injection of liquid into the pump casing. By selectively injecting liquid into specific pump chambers, it is believed that many of the vibration issues can be eliminated with the added benefit of additional pressure boosting capacity. Since this method requires extensive mechanical modifications to an existing pump, it was studied only analytically. Calculations were carried out that show that through-casing liquid injection is feasible. More favorable pressure profiles and increased boosting ability were demonstrated.

The use of twin-screw pumps for moving fluids is not new technology but its application to wet gas compression (high gas volume fraction [GVF]) is still considered relatively new. There are many advantages for using twin-screw pumps for oil field applications; three of the immediate improvements include reducing hardware costs, reducing well bore pressure, and producing a pressure boost to move the product to a central collection facility. While there are many advantages to using twin-screw pumps in wet gas applications, there are some problems that have been encountered while operating at high GVFs. When operating at high GVF, over 95 percent twin-screw pumps experience a severe loss of efficiency and an increase of operating temperature. A common way to increase the efficiency while operating in the high GVF range includes adding a liquid recirculation system where a portion of liquid is stored downstream of the pump and is injected into the pump inlet. These systems lower the effective GVF of the multiphase fluid below 95 percent in order to increase the pump efficiency. The first objective is to characterize the performance of a twin-screw pump fitted with a liquid recirculation system while operating under high GVF conditions. The second objective is to investigate the transient heat rise associated with high GVF operation. While traditional twin-screw pumps can be fitted with a liquid recirculation system to allow them to operate under high GVF conditions the pumps themselves are not optimized for wet gas compression and still suffer performance penalties. The results of this investigation show that the liquid recirculation system can allow the pump to operate under high GVF but the heat added to the system reduces the systems efficiency. Without a method of removing the heat generated in the pumping process the pump will not run at its optimal efficiency. The following investigation provides recommendations for further research in area of multiphase pumping using twin-screw pumps based on the characterization and transient studies provided in this thesis.

In this study, Effect of Molybdenum disulfide (MoS2), Anglamol(SP) and Tricresyl phosphate(TCP) additives on the tribological performance of loosing and tightening process of screw and nut were investigated by using a self-developed tribological tester. The screw and nut are made of SCM 440 and HBsC3, respectively. Result shows that the MoS2 additives with Grease#0 give the best tribological performance but TCP with Grease#0 is worst. With increasing concentration of MoS2 , the lubricant life increases, reaches a maximum at about 5wt% and finally diminishes with decreasing. Surface pressure between the screw and nut, the lubricant life increases. Under the surface pressure of 2.64kg/mm2, the lubricant life can achieve 8000 cycles or more. To maintain the long life of the screw and nut, the surface pressure should be equal to or less than 2.64kg/mm2.

ABSTRACT The greatest impact that the screw and nut industry faced currently is the continuously increasing cost of raw material. It is about 60% for the raw material in the total costs in industry chain. The cost of iron steel has increased more than 70%. The tax changes very often in China. The tax rate is very different from one to another item and from tax drawing back to tax increasing which makes about 20% price different for those middle-size manufacturers who reply on the lower cost of wire for survival. .The domestic companies in Taiwan have become competitive due to the increasing cost of raw material, market recession and more and more competitions. The current price of rod wire of China Steel Corp. is lower than the international price, but the supply amount is less than one third which makes very few suppliers own the best quality of raw material but is the lowest price. Therefore, the supply and demand disorder will happen continuously. In the cost accelerated. Significantly grow up in the cost under, therefore this research tries in the old Jing to match strategy under, look for a new profit chance, by thinking that the industry of the traditional industry-screw develops new breakthrough. This research after the sorting of the collection of literature review and data, is again currently of inventory management system and theories in the match bureau explanation manufacturing industry and the industry chain of the distributor's structure problem, aim at the letter of the research individual case company-friend of the industry of the traditional industry-screw nations, the friend camp button up a piece and hundred million Xiang hardware etc. three Jings of companies match strategy's carrying on to inquire into analysis. The business model that then aims at to produce an industry puts forth a suggestion to create currently domestic traditional industry-screw industries gathering under of competitive advantage. The research shows that the cooperation of strategy should let go of one's own opinion's establishing a product independently the marketing order, and provide oneself with the advantage, the competition ability that enhances strategy object. However after parallelism integration in traditional industry of screw, it will cause equal threat towards up and down streams definitely, therefore establishing reasonable rules for the game is rather important. However the cooperation is just a point of departure separately, therefore how extend into a whole industry cooperation, in really currently the traditional industry-screw industry rather important topic.

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