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The UV photopolymerization technology, also known as Polyjet or 3D impression, allows the manufacturing of pieces with a high dimensional accuracy, subtle details and smooth surfaces. The last developments have made possible the production, through these technologies, using two different materials and even to generate digital materials as a composition of the two base materials.
For these processes, AIJU uses Objet Connex 350, able to build final products up to 350x330x200 mm and final products with good final characteristics and similar behaviour to silicone or rubber. Their applications include, among others, the manufacturing of prototypes for benchmarking actions or the production of masters for vacuum casting moulds, moulds of wax injection to use in the lost wax technology or even high precision and detailed female electrodes, which are the most economical methodology for short production series.
Cesar Carrión, responsible for the Product Development Area at AIJU’s Product Development -Laboratory Department, says: “Thanks to the multiple variety of properties that digital materials that can be generated by the Polyjet Matrix technology present, a stiff objet with flexible buttons in the same piece seamless and without fissures or cracks can be created, for instance. This technology has also entered the customization market through specific machines for the headphone manufacturing. Its acrylic resins are homologated for uses in the health industry; one of the clearest application fields is the manufacturing of surgical splints used in non-invasive dental prosthetic surgery”.
Selective Laser Sintering (SLS) is a less accurate technology that requires the laser beam recalibration or re-adjustment system employing scale factors on the pieces to be manufactured as, otherwise, it provides a deviation regarding the original design. The scale used in SLS is very large and can show large differences in its values.
AIJU has used the scaling values of the SLS technology in order to provide a smaller scale applicable to Polyjet technology. Therefore, in the study, AIJU has achieved an accuracy 10 times the initial value calculated with no scales. Thus, Polyjet technology has become even more accurate and, optimized, can achieve exceptional accuracy values.
Cesar Carrión establishes that “other studies have been undertaken regarding the scaling of the Objet Technology. Nevertheless, the proposed model in this study is very complex and the correct scale factor is, in our opinion, as important or even more as the CAD model to be compared as well as all the possibilities in dimension marking. That is why, although the technology manufacturer tells us that it is not necessary to carry out this process, exceptional results can be actually achieved applying a scale system and an estimation of the appropriate scale factor”.
The practical application of this system has been employed for the manufacturing of the negative part, in the electroforming process, for the manufacturing of supported electrodes, in the electroforming process, by the Centre of Integrated Manufacturing in the University of Las Palmas de Gran Canaria.
This Project has been partially supported by the Science and Education Ministry into the Applied Research National Program (CIT-420000-2008-25).
About AIJU
The Toy Research Institute (AIJU) is a non-profit organization located in Ibi, the Spanish geographic centre for toys manufacturing. Its aim is to transfer and allow toy manufacturers the access to the knowledge of new technologies in order to improve their competitivity, while offering technological and financial assessment and supporting the professional development of people involved in the sector.
The 75 professionals on the staff carry out with their labour in the different areas AIJU is made up of, and this organization is provided with the required infrastructure to manage the different activities it undertakes.
AIJU is made up of 580 partners belonging, highly, to Valencian industry. From the total number of partners, 40% are toy manufacturers, 42% belong to the auxiliary industry and the rest belong to other sectors.
The department intended to carry out these tasks is the Product Development – Laboratory. Within this department, one of the most interesting innovation fields is rapid prototyping, working in the achievement of prototype moulds by means of several techniques: vacuum cast with silicon moulds, casting foundry, photopolimerization by ultraviolet light and selective laser sintering (SLS). AIJU has been working on the research of SLS Equipment for 10 years now, studying its feasibility of use in the manufacturing of functional prototypes and mould prototypes with the objective of reaching final material sets.
AIJU is an active member of the Rapid Manufacturing European Platform and the Spanish mirror led by ASERM, the Spanish Rapid Manufacturing Association. It is also member of EuMAT and Manufuture. AIJU is the coordinator of the working group “Rapid Prototyping Proposal SP3 (materials) Lab” and member of the “Materials” group promoted by REDIT between the RDT Centers of IMPIVA’s Network.
In the standard field, the entity is working on the potential feasibility of the proposed rules as well as new safety criteria for toys, with participation in several proficiency testing schemes both on a National and European Level. Thus, it is participating in the development of new standards concerning organic additives in materials for toys in the European Committee of Normalization (CEN).
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