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model are generated by the machine itself. It involves the use of multiple materials and independent heads). Before creating an object, machine deposit one layer of support material then the construction material is deposited first, and then again the support material. (6) The goal of the work is to try different production methods on one selected and challenging object, in order to evaluate pro and cons of its production according to the chosen and adopted techniques. To analyse the peculiarities of the products obtained using the three machines a brooch has been chosen, in which different types of challenges such as thickness, curves, thin borders and etc. were identified. Then a 3D model has been created in Rhinoceros software.Supports for 3DP systems are automatically designed with a different material by the machines; therefore in this case there is no need to have any supports for the model in CAD. In SLA system, supports have to be designed in software before producing; In this case for each piece different supports, depending on the thickness of the part, have been created. To understand the influence of the orientation on the final quality, each piece has been positioned differently. CRITICISMS OF THE PRODUCTIONS Different criticisms may be identified for each production technique chosen: SLA SYSTEM · Lack of support: when some parts that are overhang from the object remain without support the prototyped object has missed part in that point. So supporting an object for SLA production is one of the important steps for having a good result. · Cleaning with alcohol and air: if the prototyped object is not well cleaned, some liquid resins (more in the parts with cavity) remains and will be polymerized after UV curing. · Orientation for printing: orientation for some objects is challenging because depends on the structure of the object wrong orientation can be result in having parts filled with resin, which is the step can be easily resolved with experience. 3DP SYSTEMS: Models may break due to the fragility of the wax material. To overcome this issue, it is better to create the casting’s support in the CAD model and print the object with the support. COMPARISON In a general comparison between production machines, the “production time” and “surface quality” of prototyped model with wax and resin can be mentioned. It is noteworthy to compare the surface quality of the final produced pieces in metal materials; casting shall be done in a proper condition. But it is clear that with having a better surface quality a bet-
ter result in the final piece may be obtained. The lower precision obtained in case of models using 3DP1 results in a higher amount of work needed on the part cast from the model to get the similar surface finishing. This may eventually cause a higher loss of material. CONCLUSION The jewelry industry is a endless market to examine, in design and engineering terms it generates new and exciting challenges for rapid product development technologies and process but the important point to take away is that there are no clear technology winners at present. Each rapid manufacturing application is dependant to a wide array of solutions, and choosing the best approach isn’t simple. Choosing a specific technique depends on several things such as; clients requests, production time, cost, material and etc. Rapid manufacturing is still in an era of technological experimentation, which can be expected to last several years. FUTURE As Gay Penfold and Frank Cooper say “what we see today is only a pale outline of the future”. This research has been developed to understand main differences of the three techniques. Nevertheless the RP market offers a wide range of technologies and materials. Further studies in the knowledge of the materials are needed to find the right approach to their use for direct casting such as developing more knowledge about material characteristic and finding a right material suitable for the wide applications in fashion and jewelry fields. References 1] Actis Grande M., Forno I., Klotz U., Tiberto D., Quality Excellence in the Direct Casting of RP Resins: Reality or Fiction?, Eddie Bell (USA), The Santa Fe Symposium, NM-USA May 2011, pp. 36  Park R., The impact of the rapid product development process on the Jewellery and Artifacts sector  Penfold G. and Cooper F., Designing for rapid manufacturing and other emerging technologies, The gold industry through technology and innovation, Jewelry Technology Forum, 4th technical conference, 2008, pp.74  www.metals.about.com/library/weekly/ aa-rp-sla.htm  www.metals.about.com/library/weekly/ aa-rp-mjm.htm  Le HP (1998) Progress and trends in ink-jet printing technology. J Imaging Sci Technol 42(1):49–62  Penfold G. and Cooper F., School of jewelry, Birmingham, UK
PRO 1 · Tutte le tecniche PR possono essere utilizzate in continuo. 2 · Buona accuratezza e finitura superficiale ottenibili grazie alla resina SLA. 3 · Facilita’ di casting dei modelli 3DP. 4 · Controllabilita’ della variabilita’ dello spessore dello slice per tutte e tre macchine. PRO 1 · All RP techniques can be used continuously and unattended round the clock. 2 · Good accuracy and surface finish for SLA resins 3 · Easy casting of 3DP models. 4 · Variable slice thickness control for all three machines. CONTRO 1 · La SLA può ottenere una delle migliori finiture superficiali tra le tecnologie PR, ma il casting è più impegnativo rispetto a i modelli in cera. 2 · I sistemi 3DP possono produrre solo parti in cera, cosi che a partire dalle tecniche 3DP scelte in questo confronto, non si possono ottenere stampi in gomma. CONS 1 · The SLA can obtain one of the best surface finishes amongst RP technologies, but the casting is more challenging comparing with wax models. 2 · 3DP systems can produce only wax parts, so from 3DP techniques chosen in this comparison, mold model can’t be obtained.
VICENZAORO Goldsmith Technology Journal - VICENZAORO Winter 2014