Powder metallurgy (PM) technology has been gaining increased importance in the jewelry industry. Latest developments in stereolithography processes that allow the direct manufacture of jewelry items, namely selective laser sintering (SLS), have been pushing this technology toward large-scale utilization. The hot pressing (HP) technique can also be used in the production of jewelry parts. It has the advantage of allowing fast consolidation of the metallic powders due to the use of pressure and temperature combined, thus dramatically reducing the sintering time and producing powder compacts with very high densities (typically full density). Components thus obtained are also regarded as having better mechanical properties. It has drawbacks, though, such as the high cost of low-production cadence when compared to other mass production technologies. This problem can be mitigated by producing limited series of high-value, innovative jewelry parts.Taking advantage of the well-established CAD/CAM machining systems, it is now very easy to manufacture the complex shape dies for the aforementioned parts. In this work, the hot pressing processing parameters are analyzed in terms of impact on the mechanical and optical properties of sterling silver and colored gold compacts. A manufacturing method to obtain multi-colored jewelry pieces with color gradients is also presented.

Author: Dr. Bruno Henriques