SLS – How it works
A CO² laser fuses fine nylon powder in 0.1mm layers, directed by a computer-guided mirror. The build platform progresses downward in layer thickness steps. The delivery chambers alternately rise to provide the roller with a fresh change of powder to spread accurately over the surface of the face build area. Non-sintered powder forms a “cake”, which encapsulates and supports the model as the build progresses.
The whole process takes place in an inert nitrogen enviromnet to stop the nylon oxydizing when heated by the laser beam. The temperature inside the building chamber is maintained at 170 °C, just below the melting point of the polymer powder, so that as soon as the laser makes contact with the surface particles they are instantly fused by the12 °C rise in temperature.
Once it is complete, the build platform is raised, pushing the mixture of non-sintered and sintered parts into a clear acrylic container. The block of powder, once cooled, is diposed of in a clean-up booth and work begins to excavate the parts. The non-sintered “cake” encapsulates the parts and has to be carefully brushed away so the individual parts can be removed and blasted with a fine abrasive powder.
They are then checked, measured, bagged, labeled and then carefully packed and shipped to the customer.
This whole process can often take less than 24 hours.
Once setup the machines run unattended, allowing 24/7 production for an extremely fast turnaround service.
Unlike SLA technology, the process does not require any support structure which allows the full 3D volume of the machine to be used to build parts. This means multiple parts can be stacked in the build leading to very efficient use of capacity.
