The 3DPlate project’s scientific and technological objectives focus on the design, printing, and finally electroplating, of a wide range of 3D structures and complex geometries, based on client’s desire (customized objects). Further objective is to set up and operate a prototype vertical pilot line aiming to fabricate custom 3D-printed metallic-coated objects. Cnano will advance its knowledge on the utilization of appropriate design software, on 3D printing technologies as well as on plating on plastics processes.
- 3D Design
Rhinoceros 3D software (Rhino 6) and various open software (e.g. Blender, OpenSCAD) will be used aiming to the 3D modeling of shapes and structures. Rhinoceros is a CAD software with a multitude of 3D modelling tools, which allows to create complex shapes with great precision and detail. This will allow the easy customization of objects based on the customers demand.
- 3D Printing
Among several 3D printing technologies, within 3DPlate, Stereolithography (SLA), as the main technique, and Fused Filament Fabrication (FFF) will be utilized.
In SLA process a liquid resin is used as the source material which is placed in a vat with a transparent bottom. A UV laser traces a pattern on the liquid resin from the bottom of the vat to cure and solidify a layer of the resin. The solidified structure is progressively dragged up by a lifting platform, while the laser forms a different pattern for each layer to create the desired shape of the 3D object. The XYZprinting PartPro150 xP, having a build volume of 150 x 150 x 200 mm, is the printer that will be employed.
During FFF procedure, objects are built by heating a thermoplastic filament to its melting point and extruding the thermoplastic layer by layer. The Flashforge Creator 3, having a build volume of 300 x 250 x 200 mm, is a desktop sized FFF 3D printer in the professional system range. The dual independent extruders operating at high speeds and the extended range of compatible materials, makes Flashforge one of the best printing solutions.
- Surface treatment & Electroplating
Electroplating is the process of applying a metallic coating on a piece of metal (or another conductive surface) utilizing electric current from an aquatic solution containing the corresponding metal ions. In electroplating, both an anode and a cathode (the part to be coated) are immersed in an electrolytic bath that is composed of a solution of dissolved chemical ingredients. When an electric field is applied, the dissolved metal ions are reduced onto the cathodic surface, forming the coating. Although applying electrolytic coatings is a relatively easy process in metallic substrates, when it come to polymeric objects the process becomes challenging as they do not present conductivity. Thus, a proper preparation of the polymeric surface is required prior to the electroplating step.
Initially, the object has to be cleaned from greases or residues that are loosely attached/adsorbed on its surface via ultrasonication in alkaline solution. Then, the surface of the object must become conductive. A chemical treatment with a strong acid (chromic acid) is necessary in order to prepare the morphology of the surface, followed by immersion of the object in solution of precious metal (e.g. Pd). The latter step serves to provide activation centers in the surface that will act as catalysts/initiators during the next step in which the object is covered with a thin coating (~ 2μm) by utilization of electroless plating. This process ensures both adequate adhesion and conductivity foe the application of the final coating to the object, leading to high quality and durable products. Cnano will utilize environmentally friendly substances and processes compared with the conventional methods of pre-treatment on plastic substrates that utilizes toxic and carcinogenic substances (e.g. hexavalent chromium, Cr+6).
