Droplet deposition is a welding process in which one droplet (or a certain number of droplets) is melted off a metal wire on demand. The characteristics of the droplets are accurately defined using a number of preset parameters. These droplets have a temperature which is considerably higher than their own melting temperature and the melting temperature of the metal to be welded. This extra heat is used to melt the material to be welded, thus forming a joint with the droplet.
Droplets can be made from many filler wires including tungsten,copper,molybdenum,aluminium and alloys.
Droplets vary in size from micro droplets less than .5 mm in diameter to greater than 4 mm.
DROW is a non contact joining method, that is, there are no electrical connections to the workpiece.
The main advantages of the non contact method are:
Protection of sensitive components from high currents and voltages.
Rapid manufacturing process suitable for automation.
Process speed; a droplet forming cycle can be less than 50Ms.
Ability to join disimilar metals easily.
The enabling of welded joints to be made on a wide variety of applications where welding would not normally be considered for example - copper clad printed circuit boards.
Joints requiring high thermal stability and long term freedom from heat cycling fatigue faults.
This method of Metal Droplet Deposition, differs from other methods such as spray droplet deposition used in RAPID PROTOTYPING. The DROW process uses the droplets to form welded joints, not to manufacture parts.
Links to examples of manufacturers of DROW equipment:
The author has worked with Droplet Deposition Systems in a developing, constructing, servicing and advisory capacity.
For more information on Droplet Deposition Systems contact
