DORIAN NEDELCU, AUREL BARA, ADRIAN PELLAC, SORIN LAURENTIU BOGDAN A COMPARATIVE STUDY BETWEEN THE COSTS OF POLYMER BASED RAPID PROTOTYPING AND STEEL BASED MANUFACTURE The Pelton turbines convert hydraulic energy into mechanical energy, through the Pelton runner, by using high heads and small discharges. The runner has a complex geometry, described in drawings by transversal and longitudinal sections that form continuous surfaces. The SolidWorks software was used to design two Pelton runners: the R1 runner with 21 buckets and the R2 runner with 19 buckets. The runners were made of polymeric materials through the Rapid Prototyping process, using the Objet Desktop 3D printer, which is based on the Objet PolyJet technology, with a layer thickness of 28 microns <1>. The runners were used to measure the hydrodynamic characteristics of a Pelton microturbine on a test rig. The paper aims to highlight the advantages of the Rapid Prototyping process compared to the traditional technology used to manufacture Pelton runners that are intended for experimental research.