Is Additive Manufacturing Ready for Series Production?
Small batches and mass production are somewhat incompatible, because the lower the product price, the more important are high production numbers. While additive processes are not ready for mass production yet, they may be able to mitigate these conflicting interests.
Additive manufacturing processes are increasingly opening up new opportunities to combine aspects of serial and single-part production: Just like good craftsmen, 3D printers are very versatile and can produce different objects without requiring huge initial investments. In terms of cost structure, it makes no difference whether thousand individual or identical geometries are produced, because the modification costs are extremely low. Injection moulding machine maker Arburg, Loßburg, Germany is a company that works with both manufacturing techniques. They say that the combination of injection moulding, additive manufacturing and industry 4.0 technologies allows them to produce large series parts customer-specific in batch sizes as small as 1.
Dr Eberhard Duffner, head of development at Arburg, says about the current state of the art in additive series parts production: “Recently, Arburg presented some materials and material combinations that have real potential for the production of series parts and that in this specific way can only be machined by the Freeformer." According to Duffner, there is a wide variety of usable materials, including PC/ABS blend with flame protection, from which the experimental component "Nautilus Gear” was made, two-component planet rollers made of elastic TPU (Elastollan) and biodegradable PHA (Arboblend), a nutcracker made of bio-polyamide (Grilamid), as well as implants made of absorbable medical polylactide (Resomer), that dissolves on its own within the body after a certain time.
The processing of some bioplastics is particularly noticeable. Possible fields of application for the Freeformer are also identified in the automotive industry - for example, additive manufacturing could be used for small quantities in pre-series production. Asked about development priorities, Duffner says that the component design must meet the requirements of the production process if additive manufacturing techniques are to be used in series production. There are still a lot of unresolved issues in this respect, for example regarding appropriate design guidelines. Another huge topic in terms of suitability for series production is the predictability of quality characteristics in lot sizes of 1, since these depend on many variable slice and process parameters. Currently, the quality of printed parts is mostly assessed based on "fashionable" criteria like surfaces or construction time.
Pushing for mass customisation
In comparison, mechanical properties like tensile strength, tear resistance, density, or changes in the chemistry of the raw material are crucial in the additive manufacturing of "real" functional components, says the machine manufacturer’s development expert. When asked about short-term trends, the experts from the Black Forest have this to say: “Generally, increasing product diversity, special customer-specific small-batch solutions and short life cycles will be arguments for an increasing number of plastic processing operations to integrate an additive manufacturing system into their operations."
At Fakuma 2015, Arburg demonstrated three Freeformers for industrial additive manufacturing. Under the main topic of "production efficiency", two exhibits were illustrating the "Industrie 4.0 – powered by Arburg" concept, producing individualised high-volume injection moulded parts for mass customisation. In order to automate the Freeformer, the Arburg experts have pooled their skills to devise a solution that is truly unique in the world of additive manufacturing, the company said. The machine now features a Euromap 67 interface that allows it to communicate with the robotic system. The cover is opened and closed fully automatically and the part carrier has also been adapted.
For tool and mould makers, metal additive manufacturing is an increasingly implemented technology, as it allows to for example create complex shapes as needed for close-contour cooling channels. EOS in Krailing near Munich is a specialist for metal laser sintering technology. A selection of powders from aluminium, high-tensile maraging steel, stainless steel, and titanium to nickel and cobalt-chrome-alloys enables the flexible production of metal components. Recently, the company introduced the material "EOS Stainless Steel CX", an extremely corrosion-resistant high-tensile steel with excellent hardness. When asked about arguments for additive manufacturing, Peter Segrodnik says: “Generally, additive manufacturing has its strengths in areas where conventional production reaches its limit." According to Segrodnik, the technology comes in where construction, design and production must be rethought in order to find viable solutions. Additive manufacturing would enable a "design-driven manufacturing process” where design determines production - not the other way around! This is a clear statement aimed at the production of individual geometries that are difficult to manufacture with traditional techniques. EOS offers a high degree of design freedom, functional optimisation and integration, the production of small batch sizes at reasonable average costs and a high degree of product individualisation - also in series production. This makes it possible to utilise the benefits of additive processes in small series - a huge advantage in the manufacturing of components that cannot be produced with current technologies.
Industrialising additive manufacturing
At the last Formnext exhibition in Frankfurt, industrialisation, including how to move AM into mass production was a dominating topic as well. For instance, visitors were able to virtually explore Additive Industries' Metal-FAB1 industrial metal AM system, which celebrated its world premiere at the exhibition. The Eindhoven (NL)-based company is dedicated to bringing metal additive manufacturing for functional parts from "lab to fab", it says, by offering a modular 3D printing system and seamlessly integrated information platform to high-end and demanding industrial markets. The machine's multiple build chambers with individually integrated powder handling make this industrial 3D printer the first to combine up to four materials simultaneously in one single machine, the company explained. Furthermore, more and more companies offering complementing technologies are co-operating to move AM to the next level – including the mould and die making sector.
Additive manufacturing enables the production of metal mould inserts that feature conformal cooling to ensure and control temperature homogeneity for shorter cycle times. GF Machining Solutions and EOS collaborate to integrate AM into companies’ production process, because additive manufacturing is not employed as stand-alone technology in the mould shop. “Many solutions we have developed together with our customers are a combination of additive and substractive manufacturing processes,” EOS founder Dr Hans J. Langer says. “So from a strategic perspective it was a logical step to partner with one of the leading machine tool companies in the mould and die sector, in this case GF Machining Solutions.”
Based on proven and successful EOS technology – the EOS M 290 DMLS system – the new Agie Charmilles AM S 290 tooling solution is designed to address the mould and die industry’s need to produce innovative mould inserts using AM. GF and EOS will undertake the integration of the AM machines into the production process of mould inserts, including the necessary software and automation link with downstream machine tools and measuring devices.
When asked about challenges, the experts from EOS say: “The challenge for companies regarding the introduction of additive manufacturing processes is generally that particularly at the beginning they are still driven by conventional manufacturing processes. Components are often designed in the usual way and not optimised to meet the specific demands of additive manufacturing." Thus, the benefits of generative methods are not initially fully exploited. At this point it would be important to let go of the old way of thinking and consistently apply design guidelines for additive manufacturing. A demand Arburg supports, as the Loßburg company generally insists on adapted design guidelines.
The human factor remains one of the most important aspects
Machine tool users know Mapal Präzisionswerkzeuge Dr. Kress as a leading global supplier of precision tools headquartered in Aalen, Germany. One of the company’s particular strengths is fine machining with clamping tools. Dr. Dirk Sellmer, Head of R&D at Mapal, says: “The biggest pro for additive manufacturing is the special design possibilities it offers." Additive processes free designers from the limitations of conventional production and offer a high degree of freedom. Also, because it requires a lot less setup-time, even small batch sizes can still be produced cost-efficiently, explains Sellmer. Another advantage is the much more material efficient production, for example through integrated rib structures in the tool interior.
However, one of the most important aspects is surely the human factor! Current design education is mainly focused on conventional production, but designing for 3D printers requires a new way of thinking and the implementation of appropriate qualification measures.
This article was first published by ETMM.