Modeling of rotary screw fluid dispensing processes

Fluid dispensing is a process widely used in electronics packaging manufacturing, by which fluid materials are delivered in a controlled manner for the purpose of bonding, sealing, coating, or conducting. Among various dispensing approaches, the use of a motor-driven screw is recognized as one of the most promising approaches due to its capacity of achieving high flow rates without the need of refilling. In a dispensing process, the flow rate of fluid dispensed is critical to control the volume or amount of fluid dispensed. This paper presents the development of a model for the rotary screw dispensing process. By using the power law equation, the flow behavior of the fluid being dispensed is characterized and then, based on the fundamentals of flow in screw channels and circular tubes, a model is developed to represent the flow rate in the rotary screw dispensing process. Experiments and simulations were carried out to verify the model effectiveness as well as to investigate the performance of the rotary screw dispensing process.