Metal powder effects on selective laser sintering

Manufacturing functional prototypes and different tools using conventional methods usually is a time consuming process with multiple steps. The global economic pressure to get products to market faster has resulted in the development of several Rapid Prototyping (RP) techniques.
Layer manufacturing technologies are gaining increasing attention in the manufacturing sector. They have the potential to produce tooling either indirectly or directly, and powder metal based layer manufacture systems are considered to be an effective way of producing rapid tooling.
Selective Laser Sintering (SLS) is one of several available layer manufacture technologies. SLS is a sintering process in which designed parts are built up layer by layer from the bottom up using different powder materials. A laser beam scans the powder bed; filling in the outline of each layer’s CAD-image by heating the selected powder pattern to
fuse it.
This work reports on the results of an experimental study examining the potential of the selective laser sintering process to produce metallic parts using stainless steel powder. One material, a stainless steel powder and one sintering station research machine, which was constructed in Leeds, were used during the research. A step-by-step
investigation was conducted. The research started with sintered tracks and finished with multiple layer sintering. The purpose was to find successful conditions and to establish the main problems that need to be overcome.
The main achievements of this thesis have been to develop laser power and scan speed sintering maps for a stainless steel powder. The maps have established conditions in which multiple layer blocks can be created, have established strategies to enable large areas to be sintered without warping and show that powder particle size has an important
influence on sintering and on the position of the boundaries in the sintering maps. Although this investigation answered some questions, it also raised several more which are presented at the end of this thesis for future work.