Qualification of thermoplastic polyurethane components for media-tight applications manufactured by powder bed fusion with laser beam for polymers

Additively manufactured thermoplastic polyurethane (TPU) components for applications such as vacuum grippers or seals are of increasing interest. Porosity and surface roughness remaining from the powder bed fusion with laser beam for polymers (PBF-LB/P) process pose significant challenges to sealing performance. This work aims to evaluate the suitability of PBF-LB/P-manufactured TPU components for sealing applications, with a focus on the influence of PBF-LB/P process chamber temperature and chemical smoothing. Test specimens were produced using Monkey TPU 50 (Launhardt GmbH) on a Sinterit Lisa X machine varying process chamber temperatures from 105 to 120 °C. Mechanical properties (hardness, tear resistance, compression set) and surface characteristics (roughness) were evaluated before and after chemical smoothing. Performance was assessed via qualitative overpressure and negative pressure tests. Chemical smoothing enables the use of PBF-LB/P TPU components in media-tight applications by eliminating surface porosity and closing the part surface. In addition to lowering roughness, smoothing alters all other investigated properties: Shore-A hardness and tear resistance increase, while compression set also rises. PBF-LB/P TPU components can potentially meet media-tightness requirements when combined with chemical postprocessing. The method enables functional sealing parts like vacuum grippers with tailored geometries. Future work should investigate cyclic and dynamic sealing performance to assess long-term application suitability.