In recent years the jewelry industry has shown an increasing interest in rapid prototyping techniques as an answer to several design challenges. Even though rapid prototyping can produce models for direct casting, at the moment this opportunity is not fully exploited. One reason for this has certainly to be the lack of information about materials and their correct handling and processing, causing confusion and uncertainty when using them. Understanding of their characteristics is critical and represents the starting point for the achievement of a high-quality casting. In order to match resin requirements, many studies have been carried out in the past, reconsidering the adapting process parameters, developing new techniques and new materials to fit resin needs, and looking for practical tricks. However, great attention should also be paid to critical phases both in resin parts production (slicing and orienting of the pattern, accuracy, UV curing) and in the cycle (particularly to oxygen supply during burnout and residual evacuation). In addition to the aforementioned process parameters, several other "external factors" could also play a role in the response of resins, such as aging, packaging, cleaning, handling, etc., and their influence should be taken into account when considering results from direct casting of RP resins. Resins can differ substantially from one to another. The market offers a wide range of materials, from wax-like resins to fully polymeric ones. It is therefore essential to take into account that the final results are highly dependent on the chemical and physical characteristics of the material adopted. The aim of this work is to analyze rapid prototyping resins from a scientific approach, to derive information on the thermal and physical behavior of materials, and then to transfer that knowledge into practical applications, looking for a correlation between the material characteristics and proper processing.

Authors: Dr. Marco Actis Grande, Ilaria Forno, Dr. Ulrich Klotz