The idea to develop processes capable to produce physical components quickly and without requiring tooling, led to the development of the “free form fabrication” (FFF) or “rapid prototyping” (RP) technologies in the early 1980s. RP systems generally build up a prototype directly from the computer-aided design (CAD) data by using an additive “layer by layer” method. The RP technologies have brought several advantages to the manufacturing industry in such a way that these technologies are evolving toward the production of end-use parts. This paper presents a review of rapid prototyping and manufacturing (RP&M) technologies from their origins. The review includes commercially available RP systems and RP technologies that are still at the development stage or that have been proposed. The operating principles and the features of these technologies are presented. Process parameters such as accuracy, layer thickness, operation speed are given. An extended classification of RP&M technologies is also included in this paper.

Plasma arc welding (PAW) is a technique used in the electrical component industry for joining electrical conductors in devices such as motors and alternators. With the limited number of theoretical methods and simulation tools to predict the metal flow characteristics and its interaction with the process parameters during the welding process, weld design must still rely on the designers experience and the trial and error method. As a consequence, the process parameters and the weld quality may not be as originally expected at the design process. Based on the fact that a good quality of the final product has to be guaranteed, the analysis of the PAW process and the resulting weld quality is presented in this paper. The aim of the work was to obtain a clear perspective on the influence of various process parameters on the weld quality. In order to measure the influence on quality, first “quality” was defined. Secondly, there were various options to measure the quality, some of them being destructive, others being non-destructive. The development of the measurement methods was then proposed based on electrical tests, mechanical tests and visual inspection of the welds. Finally, using these methods and the experimental data obtained from the actual welding process, a new approach to evaluate the weld quality was proposed and is presented in this paper. The results reveal that the electrical impedance, the mechanical strength and the geometry (visual measure) of the weld are related and can be used to estimate the weld quality.