Wang, W. and Pinkerton, A.J. and Li, L. (2008) A gas-free powder delivery system for 100% deposition efficiency in Direct Laser Deposition. In: Proceedings of the 27th International Congress on Applications of Lasers and Electro-optics (ICALEO) :. Laser Institute of America, pp. 415-423.
Full text not available from this repository.Abstract
Metal powder delivery systems have been used widely in Direct Laser Deposition (DLD) processes. Most current commercial DLD systems use a gas to carry the metallic powders to the point of delivery through a feed tube and then a nozzle. The major drawback of this method is that wastage of the expensive powder is very high. To overcome or mitigate this process deficiency, a gas-free Powder Delivery System (PDS) has been developed. The system uses sonic/ultrasonic vibration to exert a distributed driving force on the powder and assist its deliver to the laser generated melt pool. Three different PDS configurations (off-axial, coaxial and multiple-stream) were designed and evaluated. Experimental tests showed that the powder flow rate from these nozzles is both highly stable and has fast dynamic response to the vibration. Trials were carried out with a 1.5 kW diode laser and a 1 kW single mode fibre laser to deposit copper, steel and Inconel 718. They showed that 100% deposition efficiency can be achieved by using the developed gas-free PDS. The deposition qualities in term of surface roughness, microstructure and porosity are studied and compare favourably with the results produced by a conventional gas feed system operating at the same parameters.