TECHNOLOGY | PRODUCT DEVELOPMENT
Above: Mechanical stress tests – in this case on a cable pulley made from Grilamid BTR 600 – have shown that tensile yield strength values comparable to those for injection moulded parts can be achieved using Arburg’s APF technology
“There is a clear trend towards faster production
Right: A Freeformer uses the high temperature plastic PEI to produce a small batch of 70 spacers, which are installed in Arburg’s Allrounder injection moulding machines
of high quality parts. Particularly in the manufacture of small volume batches, additive manufacturing will gain greater significance as the diversity of materials and cost-effectiveness increase. For use in high volume industrial additive manufacturing, the functional parts must always achieve the required quality – on a reproducible basis. For this purpose, the design must meet the requirements of the process and production method. This calls for a great deal of know-how regarding the machine, material, process and digital model. The great freedom offered by additive manufacturing with regard to the parts produced means that design guidelines are also required. These help designers to design their products from the outset such that disadvantages with regard to the part structures are excluded in advance and the potential offered by additive manufacturing is fully exploited.” Arburg adds that its customers also want to use as wide a range of materials as possible in additive manufacturing. The company says that a great advantage of Arburg Plastic Freeforming is that the process adapts to the user’s requirements and not the other way round. “The open system gives the user independence,” Duffner says. “The user’s own original material can be qualified with the Free- former and process parameters optimised specifi- cally to a particular application. Process data can be saved and analysed, and designs can be optimised quickly.” He says Arburg has made further progress in
62 INJECTION WORLD | October 2017
material qualification in recent months. The Freeformer now processes the high-temperature plastic polyetherimide (Ultem 9085 supplied by Stratasys) to produce spacers which are installed in Arburg Allrounder injection moulding machines. The spacers weigh 0.09g each and are produced in small batches of 70 units. Arburg has also expand- ed the range to include a polycarbonate material specifically approved for aerospace applications (Sabic’s Lexan 940). At Fakuma 2017, an Arburg Freeformer will demonstrate the processing of partially crystalline PP together with water-soluble Armat 12, a support material specially developed for the PP. The group develops new support materials with universities and established material partners. The water-solu- ble support material Armat 11, for example, has now been improved. Armat 21, an alkaline-soluble alternative that is particularly resistant to heat and deformation, has been available since May 2017. Duffner says: “The better the APF process is
configured, the better the quality of the part produced. One important factor here is the material discharge, the optimisation of which our experts have focused on in depth. As a result, different microstructural characteristics can be produced in a targeted manner. For example, the more densely compacted the droplets [are] relative to one another, the higher the mechanical part properties. Today, depending on the material, part densities of up to 95% can be achieved compared to injection moulding, enabling tensile strengths of up to 97% to be achieved, for example. During the Arburg Technology Days 2017, we used a mobile phone cover made from polyamide to demonstrate how optimising process parameters can improve surface quality.” Arburg says that some of its customers are already
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