Effect of Substrate Temperature on Splashing of Molten Metal Droplets

Volume 1 ◽  
2004 ◽  
Author(s):  
Rajeev Dhiman ◽  
Sanjeev Chandra
Keyword(s):  
Substrate Temperature ◽  
Molten Metal ◽  
High Impact ◽  
Small Satellite ◽  
Solid Layer ◽  
Uniform Size ◽  
On Demand ◽  
Drop On Demand ◽  
Splat Thickness ◽  
Metal Droplets

The effect of substrate temperature on the splashing of molten metal droplets was studied experimentally. Uniform-size molten tin droplets (550 μm diameter) were produced using a drop-on-demand generator. To achieve high impact velocities substrates were mounted on the rim of a rotating flywheel and heated using cartridge heaters to vary substrate temperature. Droplets hitting a smooth cold substrate splashed extensively producing many small satellite droplets and leaving on the surface a small, irregular splat with many fingers projecting from its periphery. Droplets hitting a hot substrate did not splash but spread out to form a smooth disc. A new splashing criterion was developed to calculate the substrate temperature at which this transition occurred. It assumes splashing to occur when the solid layer produced as a result of droplet solidification grows equal to the splat thickness and obstructs the spreading liquid.

Charged Molten Metal Droplet Deposition as a Direct Write Technology

2000 ◽  
Vol 624 ◽  
Author(s):  
M. Orme ◽  
J. Courter ◽  
Q. Liu ◽  
J. Zhu ◽  
R. Smith
Keyword(s):  
Molten Metal ◽  
High Speed ◽  
Droplet Diameter ◽  
Metal Droplet ◽  
Circuit Board ◽  
Charged Droplet ◽  
Direct Write ◽  
Direct Writing ◽  
Drop On Demand ◽  
Metal Droplets

ABSTRACTThe formation of highly uniform charged molten metal droplets from capillary stream breakup has recently attracted significant industrial and academic interest for applications requiring high-speed and high-precision deposition of molten metal droplets such as direct write technologies. Exploitation of the high droplet production rates intrinsic to the phenomenon of capillary stream break-up and the unparalleled uniformity of droplet sizes and speeds attained with proper applied forcing to the capillary stream make many new applications related to the manufacture of electronic packages, circuit board printing and rapid prototyping of structural components feasible. Recent research results have increased the stream stability with novel acoustic excitation methods and enable ultra-precise charged droplet deflection. Unlike other modes of droplet generation such as Drop-on-Demand, droplets can be generated at rates typically on the order of 10,000 to 20,000 droplets per second (depending on droplet diameter and stream speed) and can be electrostatically charged and deflected onto a substrate with a measured accuracy of ±12.5 µm. Droplets are charged on a drop-to-drop basis, enabling the direct writing of fine details at high speed. New results are presented in which fine detailed patterns are “printed” with individual molten metal solder balls, and issues relevant to the attainment of high quality printed artifacts are investigated.

Modeling and characterization of metal droplets generation by using a pneumatic drop-on-demand generator

2012 ◽  
Vol 212 (3) ◽  
pp. 718-726 ◽  
Author(s):  
Jun Luo ◽  
Le-hua Qi ◽  
Ji-ming Zhou ◽  
Xiang-hui Hou ◽  
He-jun Li
Keyword(s):  
On Demand ◽  
Drop On Demand ◽  
Metal Droplets

Producing molten metal droplets with a pneumatic droplet-on-demand generator

2005 ◽  
Vol 159 (3) ◽  
pp. 295-302 ◽  
Author(s):  
Stewart Xu Cheng ◽  
Tiegang Li ◽  
Sanjeev Chandra
Keyword(s):  
Molten Metal ◽  
On Demand ◽  
Droplet On Demand ◽  
Metal Droplets

Numerical Simulation on Deposition and Solidification Processes of a Molten Metal Droplet Generated by Drop-on-Demand Jetting

2012 ◽  
Vol 538-541 ◽  
pp. 890-894 ◽  
Author(s):  
Peng Yun Wang ◽  
He Jun Li ◽  
Le Hua Qi ◽  
Hai Liang Deng ◽  
Han Song Zuo
Keyword(s):  
Numerical Simulation ◽  
Substrate Temperature ◽  
Metal Droplet ◽  
Dimensional Accuracy ◽  
Droplet Deposition ◽  
On Demand ◽  
Drop On Demand ◽  
Solidification Processes ◽  
Droplet Spray ◽  
Uniform Droplet

Droplet deposition and solidification is vital to dimensional accuracy and mechanical properties of components prepared by uniform droplet spray (UDS) forming. In this paper, a volume-of-fluid (VOF) based model was developed to study the deposition and solidification processes of a 1 mm Al-4.5%Cu droplet generated by drop-on-demand jetting. The effects of droplet falling velocity (0.6-0.8 m/s), initial temperature (933-973 K), and substrate temperature (300-473 K) were investigated. The results show that the final morphology of the deposited droplet is largely dependent on falling velocity and substrate temperature. The solidified droplet obtained from an UDS experiment validates the numerical simulation.

scholarly journals Investigation of Effective Parameters of Drop-on-Demand Droplet Generator

2017 ◽  
Vol 14 (2) ◽  
pp. 182
Author(s):  
Mojtaba Ghodsi ◽  
M. Ghodsi ◽  
Y. Hojjat ◽  
H. Sadeghian ◽  
H. Ziaiefar ◽  
...  
Keyword(s):  
Molten Metal ◽  
Spherical Shape ◽  
Average Diameter ◽  
Initial Position ◽  
Droplet Generator ◽  
Effective Parameters ◽  
On Demand ◽  
Drop On Demand ◽  
Tunable Frequency ◽  
The Impact

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 droplets have been tested and discussed

Predicting Thermal Contact Resistance Between Molten Metal Droplets and a Solid Surface

2005 ◽  
Vol 127 (11) ◽  
pp. 1269-1275 ◽  
Author(s):  
Yoav Heichal ◽  
Sanjeev Chandra
Keyword(s):  
Substrate Temperature ◽  
Contact Resistance ◽  
Temperature Variation ◽  
Impact Velocity ◽  
Analytical Model ◽  
Molten Metal ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Transient Heat Conduction ◽  
Metal Droplets

Thermal contact resistance between molten metal droplets (aluminum alloy 380 and bismuth) and solid plates (steel and brass) was measured experimentally. The diameter of the droplets was 4mm, and droplet impact velocity ranged between 1 and 3m∕s. Substrate temperature was varied from 25to300°C and roughness from 0.06to5.0μm. Substrate temperature variation under impacting droplets was measured using fast temperature sensors that had a response time of 40ns and recorded substrate temperatures at five different radial locations under each droplet. Thermal contact resistance during the first few milliseconds of impact was obtained by matching measured surface temperature variation with an analytical solution of the one-dimensional transient heat conduction equation. An analytical model of the deformation of a free liquid surface in contact with a rough solid was used to calculate the true area of contact between them and, thereby, the thermal contact resistance. Test results agreed well with predictions from the analytical model. Thermal contact resistance values ranged from 10−7to3×10−6m2K∕W, increasing with surface roughness and decreasing with rising impact velocity.

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