Producing molten metal droplets smaller than the nozzle diameter using a pneumatic drop-on-demand generator

Abstract A pneumatic droplet generator to produce molten metal droplets smaller than the nozzle diameter is described. The generator consists of a heated cylinder in which a cavity is machined. A nozzle is fit into a stainless steel nozzle holder and attached to the bottom plate of the generator. The system is connected to a gas cylinder through a solenoid valve. Opening the valve for a preset time creates a pulse of alternating negative and positive pressure in the gas above the surface of the molten metal, and a droplet is ejected through the nozzle. The effect of various parameters such as the ejection frequency, nozzle diameter, pulse width and secondary gas flow on droplet formation is investigated. This method made it possible to produce droplets as small as 60% the nozzle diameter. An approximate analytical method is studied to understand the liquid behavior within the nozzle, estimate the droplet size, and investigate the effect of the secondary gas flow pressure on droplet diameter.

[1]  Lehua Qi,et al.  3D numerical simulation of successive deposition of uniform molten Al droplets on a moving substrate and experimental validation , 2012 .

[2]  Dimos Poulikakos,et al.  Transport and solidification phenomena in molten microdroplet pileup , 2002 .

[3]  Takashi Yamanaka,et al.  Generation of three-dimensional micro structure using metal jet , 2000 .

[4]  S. Chandra,et al.  Producing droplets smaller than the nozzle diameter by using a pneumatic drop-on-demand droplet generator , 2007 .

[5]  Wenbin Cao,et al.  Freeform fabrication of aluminum parts by direct deposition of molten aluminum , 2006 .

[6]  Kwang-Young Kim,et al.  Drop-on-Demand Solder Droplet Jetting System for Fabricating Microstructure , 2008, IEEE Transactions on Electronics Packaging Manufacturing.

[7]  Jiming Zhou,et al.  Modeling and characterization of metal droplets generation by using a pneumatic drop-on-demand generator , 2012 .

[8]  Stewart Xu Cheng,et al.  Producing molten metal droplets with a pneumatic droplet-on-demand generator , 2005 .

[9]  Yingxue Yao,et al.  Vibrating Breakup of Jet for Uniform Metal Droplets , 2009 .

[10]  R. Hunt,et al.  Pneumatic Drop-on-Demand Generation for Production of Metal Oxide Microspheres by Internal Gelation , 2010 .

[11]  S. Sakai,et al.  Dynamics of Piezoelectric Inkjet Printing Systems. , 2000 .

[12]  G. Switzer,et al.  A versatile system for stable generation of uniform droplets , 1991 .

[13]  Jiming Zhou,et al.  Research on accurate droplet generation for micro-droplet deposition manufacture , 2010 .

[14]  Alvin U. Chen,et al.  A new method for significantly reducing drop radius without reducing nozzle radius in drop-on-demand drop production , 2002 .

[15]  Melissa Orme,et al.  CHARGED MOLTEN METAL DROPLET DEPOSITION AS A DIRECT WRITE TECHNOLOGY , 2000 .

[16]  S. Chandra,et al.  Small droplet formation in a pneumatic drop-on-demand generator: Experiments and analysis , 2010 .

[17]  Jiming Zhou,et al.  Printing solder droplets for micro devices packages using pneumatic drop-on-demand (DOD) technique , 2012 .

[18]  Dong-Yol Yang,et al.  Drop-on-demand deposition of superheated metal droplets for selective infiltration manufacturing , 2005 .

[19]  R. Zengerle,et al.  Pneumatic dispensing of nano- to picoliter droplets of liquid metal with the StarJet method for rapid prototyping of metal microstructures , 2011 .

[20]  Hartmut Ulmke,et al.  Piezoelectric Single Nozzle Droplet Generator for Production of Monodisperse Droplets of Variable Diameter , 2001 .

[21]  Yuanhai Xiao,et al.  Manufacturing of micro thin-walled metal parts by micro-droplet deposition , 2012 .

[22]  M. Orme,et al.  RECENT ADVANCES IN HIGHLY CONTROLLED MOLTEN METAL DROPLET FORMATION FROM CAPILLARY STREAM BREAK-UP WITH APPLICATIONS TO ADVANCED MANUFACTURING , 2000 .