The Simulation of the Piezoelectric Print Head (original) (raw)
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International Conference on Liquid Atomization and Spray Systems (ICLASS)
The interest in studying droplet related phenomena has been increasing over the last decades. In the fluid dispensing equipment industry, a major problem is to minimize droplet diameter and to eject droplets in a controlled manner with a low-cost device. Taking all this into account, a new low-cost droplet stream generator was designed and fabricated. The material used to manufacture the stream droplet generator structure was a 3D printable material, namely PLA, that minimizes the device cost. This structure has three separate components: piezoelectric lid, fluid chamber, and pinhole holder. The disruptive waves of the disturbance mechanism were applied directly to the fluid instead of being applied to the precision pinhole. The interchangeable nozzle used was a round stainless-steel high precision optical pinhole with three different sizes: 100 µm, 150 µm, and 200 µm. Jet attribute properties (droplet diameter, droplet velocity, and distance between droplets) were measured as the different conditions changed (piezoelectric cell frequency, outlet pressure, and fluid). The present work studied the spray characteristics and different monodisperse regimes. A full characterisation of them is presented and discussed in detail.
An approach to design and fabrication of a piezo-actuated microdroplet generator
The International Journal of Advanced Manufacturing Technology, 2014
In this research, a piezo-actuated microdroplet printing device for drop on demand (DOD) is studied. Microdroplet devices are used in applications such as inkjet printing, rapid prototyping, and production of metal powder. An experimental device is designed and manufactured, in which the fluctuation of a flexible diaphragm-by a piezoelectric element-pushes the liquid out of the nozzle and produces droplets. The deflection of diaphragm due to different voltages is investigated by analytical and experimental study. In experiments, beside deflection voltage, the effect of suction and compression time and nozzle diameter on droplet size, droplet velocity, satellite droplets, and cutoff length is also investigated. High-speed camera is used to take photo of the formation of droplets. In order to calculate droplet diameter and velocity, outputs of high-speed camera are processed by MATLAB R2008a. Results obtained by analytical and experimental are in good agreement with each other and could be used to control droplet properties. It is shown that the device is able to produce droplet of diameter from 450 to 1,000 μm. Velocity of droplet can be also controlled in a range of about 0.2 to 1.4 m/s. The repeatability is investigated by ink printing on a paper attached to a rotary table.
Analysis of the Droplet Ejection for Piezoelectric-driven Industrial Inkjet Head
2006
A hybrid design tool combining one-dimensional (1D) lumped parameter model and three-dimensional (3D) computational fluid dynamics (CFD) approach has been developed and applied to industrial inkjet head design for the application of direct writing on printed circuit boards (PCB). Lumped element modeling technique is applied to simplify the composite Inkjet print head system and the calculation of lumped parameters such as compliance, resistance and inertance is explained theoretically. Performance of 1D analysis shows that it is useful for the evaluation of a proposed design of inkjet head. Time sequence of droplet generation is verified by the comparison between 3D analysis result and photographic images acquired by stroboscopic technique. The developed model helps to understand the drop formation process and influence of flow part on the jetting performance.
Pressure response and droplet ejection of a piezoelectric inkjet printhead
International Journal of Mechanical Sciences, 1999
The present study aims to investigate the pressure rise in the ink flow channel and the ink droplet formation process of a piezoelectric printhead after an electrical pulse is applied to the printhead. The ink flow channel is modeled as a straight circular pipe followed by a convergent nozzle. Both numerical analysis and experimental observations are performed in this study. In the numerical analysis, a characteristic method is used to solve the one-dimensional wave equation to obtain the transient pressure and velocity variations in the flow channel of the printhead. In this analysis, the channel is assumed to have a non-uniform cross section. In addition, a flow visualization system was set up to observe the ink droplet injection process. After the piezoelectric material is driven by the input electric pulse, the ink droplet images are immediately captured by a charge-couple device (CCD) camera converted to a digital image via a frame grabber, and stored in a computer. The results obtained from the experimental observations are also compared with the numerical prediction. The effects of electric pulse shape and voltage on the ink injection length and the ejected droplet weight are also presented.
Drops ejection from a capillary nozzle by Drop-On-Demand technology
Drop-on-Demand (DOD) technology enables to control the ejection of drops, from a vertically capillary nozzle, by piezoelectric stimulation. DOD applies in microfluidics, from the ink-jet printers to Bio-MEMS. This study emphasizes on the numerical simulation of the drop evolution during its formation and ejection by DOD technology. The highly distorted interface evolution represents an axisymmetric transient free-boundary problem, which is modelled here through a Boundary Element Method. An irrotational flow model can reproduce most observed experimental data on drop size, velocity, frequency, and conditions for non-satellite formation. Viscous effects are included to some extent, as it is allowed for potential flows of fluids with constant viscosity, the normal viscous stress at the interface being expressed in terms of the velocity potential. The time progression is made with a 4th order Runge-Kutta explicit numerical scheme. The time step is varied upon a stability criterion. The...
Piezoelectric droplet ejector for ink-jet printing of fluids and solid particles
Review of Scientific Instruments, 2003
In this article, we present a technique for the deposition of inks, organic polymers, and solid particles, using a fluid ejector. The ejector design is based on a flextensional transducer that excites axisymmetric resonant modes in a clamped circular plate. It is constructed by bonding a thin piezoelectric annular disk to a thin edge clamped circular plate. Liquids or solid particles are placed behind one face of the plate which has a small orifice (50–200 μm diameter) at its center. By applying an ac signal across the piezoelectric element, continuous or drop-on-demand ejection of photoresist (Shipley Microposit S1400-21, S1400-27, S1805, and S1813), oil-based ink, water, or talcum powder [Mg3Si4O10(OH)2] has been achieved. Successful deposition of a photoresist has been accomplished without spinning, and thus without waste. A boundary integral method was used to numerically simulate drop formation from the vibrating orifice. Simulations have been used to optimize ejection performa...
Journal of Micro/Nanolithography, MEMS, and MOEMS, 2010
Numerical calculations are performed to investigate the effect of the component of a single transducer pulse on the ejection of a drop for a drop-on-demand ink-jet printhead with a piezoelectric actuator. The flow field is governed by continuity and Navier-Stokes equations. A volume-of-fluid method with a piecewise-linear interface construction is used to track the complicated topological variation of the liquid-gas interface. The computer code is validated with experimental results present in the literature. The volume of the primary drop is closely related to the maximum displacement D f of chamber wall induced by the piezoelectric actuator in the forward stoke; the velocity of the primary drop depends on the ratio of D f to the time period of the forward stoke ⌬ f. Moreover, the fact that the formation of the primary drop depends weakly on the conditions of the backward stroke is considered. A decreased interval between forward and backward strokes might serve to suppress the formation of satellite drops owing to reducing the liquid thread length l b at pinching off to a value less than the upper limit l b *. The breaking up of the freely flying liquid thread from nozzle outlet has two modes-multiple breaking up and end pinching-and depends on the thread length at pinching off.
A low-cost, precise piezoelectric droplet-on-demand generator
Experiments in Fluids, 2015
repeatable experiments require a reliable and precise droplet generation technique. Repeatable droplet generation is also required for a number of diverse applications ranging from inkjet printing to liquid crystal display manufacturing (Fan et al. 2008). A variety of droplet-on-demand (DOD) generators are described in the literature, but most existing designs are complex, costly, and difficult to adopt for use in other studies. Many systems are designed for the generation of droplets smaller than 500 μm in diameter (
Experimental investigation of the Microdrop pump MD-k
This report describes the results of experiments that have been performed with Microdrop MD-K-140H piezo electric driven single nozzle droplet-on-demand printheads. Such printheads are used for manufacturing biosensors. Surface tension is a key parameter for understanding droplet formation of droplet-on-demand ink jet heads. Surface tension can be influenced by storing the ink in a bottle for a longer period of time.
Investigation of Effective Parameters of Drop-on-Demand Droplet Generator
The Journal of Engineering Research [TJER], 2017
This article presents a design and development of a drop-on-demand (DOD) droplets generator. This generator uses molten metal as a liquid and can be used in fabrication, prototyping and any kind of printing with solder droplets. This setup consists of a vibrator solenoid with tunable frequency to produce a semi-spherical shape of molten metal, close to the surface of fabrication. This design also has a nozzle with micro-size orifice, a rod for transmitting force and a heater to melt the metal and keep it in superheat temperature. This DOD can produce droplets in different sizes (less than 550 µm) by controlling the vibration frequency of solenoid. This ability together with the accuracy of the droplets in positioning (the error is less than ±20 µm for 1.5 mm amplitude) can be used in different applications. Moreover, in this paper, the impact of initial position of the head and temperature on the average diameter of droplets and the impact of the frequency on the shape of the dropl...