Thermoforming / Rigid
Thermoforming / Rigid Packaging Moulds for thermoforming and blow moulding Short series production moulds for bioplastics in packaging Consumers increasingly demand more sustainable products and, fortunately, this trend is being increasingly supported by novel material developments, among other measures. The consumer products industry, such as packaging, toys, etc. is conscious about achieving European environmental targets and users demands. Therefore, they are focusing their efforts in decreasing their environmental impact through different routes such as technology optimisation, new products conception or biomaterial implementation. Nevertheless, bringing new products to market requires an important investment in both cost and time, and this is even more difficult when introducing innovative materials which are totally new for the company. The product development cycle of new consumer goods can be greatly accelerated thanks to the additive manufacturing (AM) technologies, which allow the production of prototype moulds which are quicker and cheaper than conventional ones. Owing to the advances in AM materials and technology, these prototype moulds can be used for the production or even the customisation of short series of final products, ready to test or to sell. The Innovative Materials and Manufacturing area of AIJU has been researching on these two lines during the last 15 years: biomaterial developments for AM or conventional processes, and AM prototype moulds, collaborating with different consumer product companies in the conception and launching of new products. Considerable progress has been made in the understanding of the possibilities of current AM polymeric materials, design limitations and optimization of manufacturing parameters, achieving the manufacturing of moulds to produce pre-series or short series of thermoplastic parts. These parts are no longer considered as prototypes but as final products, where the materials and properties are identical to those obtained through a large-scale conventional manufacturing process, but in very short timeframes and at a lower cost. Moreover, new bioformulations based on biodegradable or biobased polymers filled with natural additives, such as cellulosic fibres, almond shell or CaCO 3 from eggshell, have been successfully processed with the developed AM moulds. Thermoforming Fig. 1 shows some examples of thermoforming polymeric moulds for packaging manufactured by three different AM technologies: laser sintering (using polyamide material), 3D printing Polyjet (with acrylic resin) and FDM (with ABS). As the AM process works adding successive layers, the mould designers can take profit of the freedom of design, being able to carry out topological optimisation or other required features during the mould manufacturing. Fig. 1: Thermoforming prototype moulds manufactured by AM technologies and materials: a) laser sintering DTM 2500 plus equipment with PA12 and PA12+Aluminum, b) FDM DT600 with ABS filament and c) Stratasys ® PolyJet J750 with acrylic resin. In the case of polyamide moulds, it is worth highlighting that the intrinsic porosity of the sintered parts facilitates the vacuum step without the need of machining vacuum channels in the mould. Another remarkable characteristic of these moulds was the as-produced surface texture, which is reproduced in the thermoformed parts. A surface finishing can be applied to the moulds in order to produce smoother cavities. However, companies liked the result, as sometimes the moulds are specifically textured to get this type of aesthetics. Polyjet technology works with a high printing resolution of 30µm, thus the moulds presented a very high surface quality compared to the FDM moulds, as can be seen in Fig. 1, in which the surface finishing was not so good according to the quality required by the final packaging and, in this case, post-processing is necessary. Mechanical properties of the moulds were satisfactory in all cases and the thermoforming process was carried out successfully by using PET material, ending in a series of product ready to use, as can be seen in Fig. 2. Other biomaterials, such as bioPET (30 % biobased content by weight) or PLA sheets can be used for the thermoforming of these products. Fig. 2: Products manufactured by using the AM thermoforming moulds with PET. a) b) c) 12 bioplastics MAGAZINE [02/20] Vol. 15
Machinery By: Asunción Martínez-García, Nacho Sandoval-Pérez, Miguel Ángel León-Cabezas, Ana Ibáñez-García AIJU, Innovative Materials and Manufacturing Area Ibi (Alicante) Spain Blow Moulding Another demonstrator of a blow moulded package (see Fig. 3) has been developed by manufacturing the prototype mould with PolyJet 3D printing technology. The blowmoulding package is generally a product that requires low thickness and the final properties, quality and performance of the final product need to be validated. This example required a short series of 50 bottles of different materials: high-density polyethylene (HDPE) and biobased polyethylene (bioPE) filled with natural wastes (cellulosic fibres, almond shell or calcium carbonate (CaCO 3 ) from eggshell). Customisation possibilities were added during the design of the mould by a modular and parametric design of the bottle, contemplating three design options of the central body. The exterior of the mould, as well as other requirements (anchors, positioning, material inlet nozzle, type of closure, etc.), were designed subject to the extrusion blow moulding machine to be used available at AIJU. Three different biobased materials were developed The biobased materials were successfully processed by slightly varying the blow moulding process parameters used for HDPE, obtaining the expected 50 units of bottles (Fig. 5). Due to the polymeric nature of the mould, it was only necessary in the blow moulding extrusion process to contemplate a cooling time greater than that usually required in conventional metal moulds. The advantages of these moulds are the lower cost compared to the metal ones and that they can be obtained within a period not exceeding 5 business days, being also a more sustainable cycle. Fig. 5: Blow moulded bottles obtained with the prototype mould with different materials: HDPE and bioPE with almond shell, cellulosic fibres and CaCo 3 from eggshell. These studies have demonstrated the wider possibilities of combining AM technologies and biomaterials for improving new product development from an environmentally friendly point of view. This more sustainable solutions will allow consumer industries to obtain a competitive advantage and a position ahead of their competitors. Fig. 3: Prototype mould/insert for blow moulding manufactured by AM technologies Stratasys® PolyJet with an acrylic resin. by extrusion-compounding of the bioPE supplied by NaturePlast (Ifs, France) with 30 wt% of cellulosic fibre Arbocel ® from Rettenmaier (Rosenberg,Germany), almond shell (of < 0.5 mm particle size), supplied by Nutrición Animal Hermen (Alcantarilla, Spain) and CaCO 3 OVOCET ® from Eggnovo (Villatuerta, Spain) (Fig. 4). AIJU would like to acknowledge the companies Exclusivas Rimar (Suavinex), Indesla, and Sarabia Plastics for their collaboration in the prototype mould cases. Authors also thank the Valencian Institute of Business Competitiveness (IVACE) for the financial support of biomaterials and AM moulds developments. www. aiju.es Fig. 4: Bio formulations with almond shell, cellulosic fibres and CaCo3 from eggshells developed in AIJU and used for blow moulding of bottles. bioplastics MAGAZINE [02/20] Vol. 15 13
