1,720,989 research outputs found
Investment Casting of Precious Metals: Materials and Methods
No full textAim of this work is the analysis of the materials and parameters related to the investment casting process,mainly focusing on peculiarities and criticisms of the casting of precious metals in jewelry production.Precious metals casting is traditionally and historically targeted to overcoming limitations in terms of geometries and final quality of the cast part. Moreover, an increasing interest rises concerning the use of new technologies and the industrializations of typical handcraft skills. New materials are therefore introduced into the process, in order to be able to get thin and intricate shapes, hollow parts and innovative design features. This is leading to a substantial rearranging of the process, with a constant innovation regarding technologies and medication of traditional materials. Considering the whole process, nvestment casting is dealing with a wide range of materials, from metallic, polymeric and ceramic classes. All these materials cannot be considered as single identities, but their synergetic behavior has to be studied, not just meaning that all of them contribute to the final quality of the cast part, but taking into account possible mutual interdependencies. The research work has been divided in a preliminary analysis of the process, in order to deepen the knowledge about material features, and in a extended study on the application of competences deriving from other sectors to the specific one. In fact it's almost impossible to find sector boundaries between jewelry and fashion accessories both in terms of process and in terms of market. Therefore the analysis of the state of the art has been widened to other processes and applications, in particular focusing on fashion accessories and eyewear component production. Market analysis clearly show a high interest of jewelry towards innovative processes/materials, often deriving from completely different fields of application. For this reason, an analysis of the investment casting process applied in the automotive and biomedical sectors can give valuable hints for the jewelry production optimization. Particular attention has also been paid to fluid dynamic analysis of the casting system, considering metal flow into the flask and following cooling and solidification. For this purpose, computational fluid dynamic has been applied to the process. Material analysis, needed for both the simulation and for a complete understanding of the process, has been carried out. Physical and thermal properties of metals and investment materials have been analyzed in order to get a proper database for casting simulation. Waxes and resins have been tested both in terms of thermal, mechanical and chemical characteristic, in order to understand their respective roles into the process and try to optimize them. Following the analysis, process implementation has been performed in order to apply information deriving from experimental tests to the process. Many parameters can be taken into account when optimizing precious metal casting; in order to focus the research activity, some limitation in terms of process have been applied. Casting trails were conducted using a static vacuum casting machine on sterling silver and 18 kt. Gold alloys, referring to traditional investment casting proces
Direct casting of Rapid Prototyping resins for luxury production: influence of burn-out and processing parameters on the final quality
No full textJewelry and fashion industry has shown and increasing interest towards Rapid Prototyping (RP) techniques as an answer to several design challenges, both for the production of final components and as a tool in the traditional investment casting process. Even though RP allows the production of complex patterns to be used for direct casting this opportunity is not fully exploited at the moment, mainly due to a lack of knowledge on the material properties and proper processing conditions. Being the traditional investment casting process required to be adopted, studies have been conduct either to modify resin properties or to reconsider or adapt process parameters. The understanding of resins properties and their mutual relation with process conditions and materials is an additional critical aspect, representing the ideal starting point for the process optimization. Aim of this work is to focus on the use of RP resins in the luxury casting. Through the materials characterization and the analysis of their properties, the limits deriving investment and burn-out are identified and process criticisms overcom
Il processo di fusione diretta di resine da prototipazione rapida:importanza di un approccio scientifico per la realizzazione di prodotti di qualità
No full textInfluence of sintering atmosphere on properties of sinterhardened steels
No full textThe aim of this paper is to deepen the understanding of the influence of sintering atmosphere on the final properties of sinter-hardened steel components. A commercial Astaloy CrM powder has been uniaxially pressed in different shapes, identified in
terms of area/mass index, with three different carbon additions (0.3 , 0.4 and 0.5 % w.) Sinter-hardening process has been conducted in a belt-furnace in order to re-enact industrial working conditions using six different protective / carburizing atmospheres. During the process, temperature profiles and atmospheres have been sampled
and analyzed. Sintered samples have been analyzed in terms of oxygen contents, hardness and microstructure. Particular attention has been paid to the decarburizing/carburizing effect of different atmospheres in terms of composition and the resulting mechanical properties
Sinterizzazione: applicabilità di tecniche differenti di metallurgia delle polveri al settore orafo.
No full textLa metallurgia delle polveri è da tempo una tecnologia largamente utilizzata in diversi
settori industriali che recentemente ha suscitato forte interesse nel mondo orafo,
soprattutto sfruttandone la combinazione con tecniche di prototipazione rapida quali la
sinterizzazione laser.
La sempre crescente disponibilità di leghe dalle caratteristiche avanzate, siano esse
basate su metalli preziosi o non, fornite sotto forma di polveri apre le porte all’utilizzo di
tecnologie di sinterizzazione alternative, mutuate da settori affini.
Questo lavoro si pone quindi come scopo l’analisi di diverse tecniche di sinterizzazione
evidenziandone pregi e limiti, anche in funzione dei diversi materiali utilizzati
“I Have Your Back” — How Innovative and Advanced Materials Cover Design in Complex Model Manufacturing
No full textAesthetics and design have become critical factors for the jewelry industry,
especially considering that product value no longer concerns just precious
metal content but is more and more related to fashion trends, innovative design concepts, and new artistic expressions. In the last decade the jewelry industry has therefore shown an increasing interest in innovation, both in terms of design and production capabilities. Digital modeling is becoming essential, allowing designers to fully express themselves. This powerful technique is completely exploited only when coupled to innovative production processes and materials. Designers then have to analyze and further deepen their knowledge of new processes in order to shape their ideas, using technical and constructive parameters completely different from traditional handicraft criteria. Their intensive use is leading to better application of new technologies, taking full advantage of all possible potentials.
The aim of this work is to analyze a real-case scenario and to show an example of the “idea to product” path, mainly taking into account technology options and their feasibility and effectiveness. The direct casting of RP models and the use of soluble resin core techniques are considered and compared during the designing of hollow jewelry parts
Influence of processing parameters on the mechanical properties of Electro-Sinter-Forged iron based powders
No full textThe paper investigates the effects of the processing parameters of an innovative electro-discharge sintering process named Electro-Sinter-Forging applied to a Fe-Cr-Mopowder. Consolidation is obtained by the superposition of a single electromagnetic pulsewith a single mechanical pulse. Two high-speed numerically controlled axes are used in the manufacturing process, operating in synchrony with the electromagnetic pulse. Through an analysis of covariance (ANCOVA) on the experimental data, the differences and correlations in density, pressure before discharge and after discharge, the thermal energy from Joule heat and the transverse rupture strength (TRS) are evidenced. Fracture surfaces are observed and analyzed. A comparison with the conventional press and sinter production process is also performe
Potenzialità tecniche e creative della progettazione al computer di manufatti preziosi: l'uso di Grasshopper nel settore orafo
No full textINFLUENCE OF GEOMETRY AND COOLING RATE ON PROPERTIES OF SINTER-HARDENED STEELS
Full text linkThe aim of this paper is to deepen the understanding of the influence of the cooling step on the final properties of sinter-hardened components, mainly focusing on part geometry (through the definition of an A/M ratio) and cooling rate. A commercial Distaloy DH powder has been uniaxially pressed in different shapes, identified in terms of area/mass index, at three different compacting pressures (500, 600 and 800 MPa). During the sinter-hardening process, conducted in a belt-furnace, temperature profiles and atmosphere have been sampled and analysed. Particular attention has been paid to the cooling step, carried out at different furnace settings (10 to 80% of the maximum cooling capability in terms of fan speed). Sintered samples have been analysed in terms of carbon and oxygen content, hardness and microstructure. The considered properties have then been compared with dilatometer data, derived from literature. Matching these properties, a correlation between furnace setting, shape and microstructure has been drawn
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