Low Temp Laser Sintering

The laser-sintering process has, beside all the advantages like a high productivity and a great design freedom, significant disadvantages with the low material variety and material ageing. A major proportion of all LS components are still made of PA12 and PA11. High performance materials e.g. PA6, PPS, PEKK, etc. are appearing increasingly on the market but they cannot be processed on standard LS systems due to the higher processing temperature. High temperature systems, on the other hand, are very cost-intensive. Additionally, the surrounding and unused powder material ages due to high process temperatures, resulting in not fully reuseable material which is not very sustainable and leads to increased costs.

Low temperature laser sintering addresses those problems by drastically reducing the process temperature, so that the material undergoes significantly less aging. In addition, the method of low temperature laser sintering enables standard laser sintering systems to process high-performance polymers. However, the process-related changes in parameters, which include adjusted exposure parameters and strategies in addition to the reduced build chamber temperature, also create new challenges. The high temperature gradients between the melt and the powder bed can lead to early recrystallization of the melt which might result in the so-called “curling” of the component´s top layers and the warpage of the whole component which further might lead to job aborts. By connecting the components to the building platform “curling” and warpage should be avoided to significantly increase the process stability. In addition to the advantages already mentioned, low temperature laser sintering can bring further benefits such as new design freedoms.

Low temperature laser sintering of Polyamide 12 (PA12) on a commercial, unmodified laser sintering system (EOS P396) is investigated to create the basis for Low Temp LS of high temperature materials. First results by changing the exposure parameters and by fixing parts on a building platform show a processing of PA12 at a build chamber temperature at 80°C and less instead of standard approximately 175°C.