Final introduction of the 1980s emerged a variety of manufacturing technologies known as Rapid Prototyping and Manufacturing (RP & M). These new technologies can generate physical objects from a computer model created in a CAD system. All these technologies have in common an important fact, the generated object is obtained by adding material, not deleting. This is because they are based on the techniques of manufacturing layered (Layer Manufacturing Technologies). The ability of visualization of three-dimensional designs, the decrease in the time required to produce prototypes, the reduction of costs associated with the Elimination of redesigns in the early stages of design, geometric freedom, parts are some of the advantages offered by these processes. However one of the disadvantages posed by materials of sintered is that the material in powder not sintered during the process can be reused only a limited number of cycles, since during the phase of warming in the camera of sintered, said material it loses properties and is discarded. The material remains at a temperature near the melting for more or less long depending on the size of the piece to build. This makes some fractions of the polymer are decomposing and some additives will degrade.
This material is mixed with Virgin material in a certain proportion however after about 15-20 cycles is discarded, with the consequent economic cost that this entails, and the environmental impact that generates. In order to obtain a more efficient use of the material in order to minimize their consumption and optimize the frequency of replenishment of the Virgin material has been developed a systematic method for determining loss of properties and its potential for reuse. This methodology is based on the determination of the MFI of the material not sintered during the process of SLS. Previous studies claim that the MFI is quick and simple method for measuring the pace of degradation of dust due to the SLS process.