26 MPR November/December 2013

special feature

0026-0657/13 ©2013 Elsevier Ltd. All rights reserved

Additive manufacturing positioning

HIP

Partweight

!pma.com Nb.of parts

... is complementary to otherPM net shape technologies

Press & SinteringAdditivemanufacturing

MIM ADDITIVE MANUFACTURING

rapid prototypingrapid manufacturing

3D printing

selective laser melting (SLM)selective laser sintering (SLS)electron beam melting (EBM)laser metal deposition (LMD)

additive fabrication,additive processes,

additive techniques,additive layer manufacturing (ALM)

layer manufacturing

freeform fabrication (FFF)solid freeform fabrication (SFF)

In 2013 a relatively new manufac-turing technique jumped into the public domain, attracting notice with inexpensive home-operated

apparatus for making toys, games and household objects, even car spares, and spectacular ‘breakthrough’ objects from fully-working guns to the ‘Queen’s Baton’ promoting the Commonwealth Games. Blessed with a variety of names, the general public seem to have seized upon ‘3D manufacturing’ as a generic, whilst professional industry prefers ‘Additive Manufacturing’.

Among the further subdivisions are those describing the form and composi-tion of the input material – whether

EPMA adopts Additive Manufacturing and launches specialist group at Gothenburg

powder, wire, tube or rod, and whether metallic or non-metallic. Amateurs often employ plastic rod or tube for input, whilst metallic powders are increasingly preferred as manufacturing or operational temperatures are raised, or specifications become more onerous. Figure 1 illustrates the current place of additive manufacturing in the spectrum of PM manufacturing choices. 2014 should be a particularly interesting year, when some of the key patents on laser sintering will expire.

The explosion in affordable additive production (mostly of plastics but also some low-melting-point metals), has energised the inventive-names industry,

my current favourite being MakerBot Industries’ ‘Thing-O-Matic’. A few more are shown in Figure 2.

At the European Powder Metallurgy Association’s PM2013 Conference in Gothenburg, we had to wait for the last morning and a Special Interest Seminar to hear from the EPMA’s new Additive Manufacturing Group and the surpris-ing progress made in recent years.

EAMGBy necessarily restricting their interests to production utilising raw materials in metallic powder form, both the EPMA and Metal Powder Report focus on the

The European Additive Manufacturing Group was formed by the EPMA in May 2013; however, PM2013 in Gothenburg was its first public gathering. Consultant Editor Ken Brookes reports on the Special Interest Seminar and the progress being made in this exciting area.

Figure 1: Additive manufacturing positioning. Figure 2: Terminological classification of AM.

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most difficult area of AM. Recent rapid developments created the need for a specialist EPMA group, not only as a forum to exchange ideas and techniques but also to promote the industry and the ever-widening scope of its products.

The European Additive Manufacturing Group was launched in May 2013, but PM2013 in Gothenburg was its first public appearance. It has two co-chairmen, Claus Aumund-Kopp (Figure 3) of Fraunhofer IFAM, Germany, and Ralf Carlström (Figure 4) of Höganäs Digital Metal, Sweden. Other members of the steering group (Figure 5) are Olivier Coube (EPMA Technical Director), Keith Murray, Sandvik Osprey, UK (standardisation) and Adeline Riou, Erasteel, France (promotion and events). Membership is open to all EPMA members.

EAMG objectives include the following:

To increase awareness of Additive •Manufacturing technology, with a special focus on metal powder-based products.To gain the benefits of joint •action, for example through research programmes, workshops, benchmarking and exchange of knowledge.To improve the understanding of •the benefits of metal-based AM technology by end users, designers, mechanical engineers, metallurgists and students.

Table 1: EAMG activities: calendar of eventsDates Event Country City LinkSept 18 EuroPM – SIS on AM Sweden Gothenburg www.epma.comSept 19 3DP.SE Sweden Kista http://3dp.se/Sept 19-20 RM Forum 2013 Italy Milan www.eriseventi.com/Sept 25-26 TCT Show UK Birmingham www.tctshow.com/Oct 7-8 AMSI India Bangalore www.amsi.org.in/Oct 30-Nov 1 RAPDASA 2013 South Africa Golden Gate Park www.rapdasa.orgDec 3-6 Euromold 2013 Germany Frankfurt www.euromold.com/Feb 6 EAMG meeting Germany Frankfurt Airport www.epma.comMarch 12-13 DDMC Fraunhofer Germany Berlin www.ddmc-fraunhofer.de/April 6-10 AMUG 2014 USA Tucson www.additivemanufacturingusersgroup.com/May 14-15 Rapidtech Germany Erfurt www.rapidtech.de/en/homepageMay 18-22 World PM USA Orlando www.mpif.orgJune 9-10 Rapid 2014 USA Detroit www.rapid.sme.orgJune AEPR France Paris www.afpr.asso.frJuly 8-9 AM Conference UK Loughborough www.am-conference.comSept 21 24 EuroPM Austria Salzburg www.epma.com

Figure 3: Co-chairman and presenter Claus Aumund-Kopp of Fraunhofer Institut, Germany. (Copyright © Kenneth JA Brookes 2013)

Figure 4: Co-chairman and presenter Ralf Carlström, general manager of Höganäs Digital Metal, Sweden. (Copyright © Kenneth JA Brookes 2013)

Figure 5: EAMG Steering Group. (Copyright © Kenneth JA Brookes 2013)

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To assist in the development of •international standards for the AM Sector.The first tangible action of the •EAMG was the production of an excellent introductory leaflet (Figure 6), with contributions from 14 EAMG members. It’s available in print and online, at www.epma.com, and I strongly recommend it.By no means fully comprehensive,

Table 1 lists some of the additive manufacturing events to be attended or supported by EAMG members in the 12

research and development trends in metallic powder-based AM proc-esses. He included examples of specific research projects and described their needs in terms of data handling and other aspects. Fraunhofer is deeply involved in this area, with both laser and electron-beam melting facilities for current research on aluminium, steel, Inconel and other metals. Seven com-panies were included on the list of AM equipment suppliers.

The presenter described how den-tal restorations were being produced by AM at a rate of 2000 a night at a single location, 500 on each of four machines. Building ‘envelopes’ (maxi-mum unit volume in terms of length, width and height) were continually being increased. New techniques, unmatched by any other production method, included hollow parts, espe-cially for medical equipment, with very thin walls and internal geometrical complexity.

RFID chips integrated into larger components by AM, were readable though completely covered by unbro-ken metal. Significantly greater surface area had been attained in an Inconel heat exchanger without an assembly operation. IN718 turbine discs with integral blading had replaced invest-ment casting. And pieces could now be made with combinations of material properties, for example a porous core with dense shell or vice versa.

Figure 6: Additive Manufacturing Technology: an introductory 4 page illustrated leaflet from EAMG.

Figure 7: Powder metallurgists in the EAMG Seminar audience displayed great interest in the contributions. (Copyright © Kenneth JA Brookes 2013)

months beginning with the Gothenburg launch event. The Orlando conference in May 2014 could be especially inter-esting, as it will parallel the World PM Congress taking place at the same venue and dates, with the same organiser.

The next EAMG meeting takes place at Frankfurt Airport, Germany. Contact for those interested in attend-ing is Olivier Coube, EPMA Technical Director, at oc@epma.com.

Sign-off from the group is “Welcome to the new world of AddiCtive Manufacturing!”

SeminarThe Special Interest Seminar on State of the Art and Emerging Markets for Additive Manufacturing (Figure 7) occupied the final half-day of the EPMA’s 2013 Conference in Gothenburg. In addition to Adeline Riou’s introduction to the new AM Group, several papers were presented. Though not published in the official Conference Proceedings, between them they covered the subject of additive manufacturing in great style, though of course only for metal powder products. I noted some of their facts and figures.

R & D on Metal Based Additive Manufacturing, Claus Aumund-Kopp of Fraunhofer, Germany.

In his presentation, Aumund-Kopp provided an overview of current

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Phase 3: New AM Design

Phase 2: Substitution

Phase 1: Tooling, Rig and Development

Manufacturing of tooling, Rig-and development hardware

Cost e�ective manufacturing of raw parts Substitution of castings

Manufacturing of functional structures to reduces weight and cost (bionic design)

As part of its extensive research, Fraunhofer was now going over from mixed to pre-alloyed powders. Particle shape and grain-size distribution were important to the attainment of even layers during AM and attracting increased effort, as was the projected changeover from batch to continuous production.

Answering questions, Aumond-Kopp explained that, with metal-powder AM, selection of either laser or electron-beam melting needed careful consid-eration of the design. Laser provided the best surface quality, but EB gave faster build-up and better mechanical properties.

Finally, Aumund-Kopp mentioned the Direct Digital Manufacturing Conference to be sponsored by Fraunhofer in Berlin during March 2014.

Additive Manufacturing for Jet Engine Parts – Today’s Applications and Future Potentials, Georg Schlick of MTU Aero

Engines, Germany.As a potential user of high-value

components made by additive manu-facturing, it would be hard to better MTU, not only an important builder of gas turbines but also the world’s largest independent provider of MRO (maintenance, repair and overhaul) for such important international engine programmes as the V2500, CFM56, PW1000G and CF34. Annual revenues were more than €3.7 billion, of which 14.8% was military and the remainder commercial.

MTU, said Georg Schlick (Figure 8), was well past the purely experimental phase of additive manufacturing and into development and commercial production in a number of high-tech areas. Parts procurement included the manufacture of rapid prototyping parts, AM tooling and rig or developmental hardware. Production plant included two DMLS (direct metal laser sinter-ing) ‘technology’ machines (M270 and M280) and four more M280 machines for production, mainly with IN718 currently (Figure 9).

Materials capabilities included a range of alloy steels, as well as estab-lished superalloys like IN718 and MAR-M509, based on nickel and cobalt respectively, and even newer high-temperature engine alloys.

The MTU ‘roadmap’ has taken the company through three phases (Figure 10), progressing from initial development through substitution of existing parts to direct design of com-ponents for the new process, taking full

advantage of its potential for weight-saving and cost reduction.

Phase 1: Tooling, rig and • developmentPhase 2: Substitution•Phase 3: New AM design•Schlick took us through the idi-

osyncrasies of AM design, with many examples, demonstrating not only the possibilities of AM generally, but also their implementation through targeted powder metallurgy. Figure 11 depicts some of the parts designed during Phase 3 of the roadmap, of which perhaps the most notable are sample turbine blades with extremely complex internal cooling passages. Serious production of flight parts was expected in the near future.

This presentation was followed by arguably the best Q&A session of the seminar, with frank answers providing useful practical information. Here’s a brief summary related to MTU’s AM parts.

Shrinkage on cooling is modest, but •residual stress is a problem.Porosity is very low but MTU is •“trying to do better”.With laser melting, thickness •of individual layers is typically 20-50µm, depending on particle size (layers are one particle thick). EBM (electron-beam melted) layers are generally thicker, around 100µm. In spite of this, laser is preferred because EBM gives a poorer surface finish and problems in the reuse of residual powder.Fatigue properties are not an issue •at the moment, but could be in the future.

Figure 9: EOSINT M270 and M280 AM laser sintering machines at MTO Aero Engines, Germany.

Figure 10: MTU roadmap to implement additive manufacturing.Figure 8: Presenter Georg Schlick of German aero-engine manufacturer MTU. (Copyright © Kenneth JA Brookes 2013)

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Post-treatment is sometimes needed, •for example heat treatment of Inconel, but so far no HIPing.Titanium AM components are pro-•duced elsewhere, but not yet at MTU.To a final question about O• 2 in superalloy powder, the answer was “No problem at the moment. We live with it.”

Digital Metal, Co-chairman Rolf Carlström of Höganäs Sweden.

Much of the company’s AM expertise was derived from its 2011 acquisition of Foubic, with technol-ogy quite different from today’s norms but cemented by its registration of the trademark ‘Digital Metal’.

Carlström said that, for Höganäs, additive manufacturing was becoming

more commercial, initially with small numbers but increasing complexity. Ink-jet print technology was employed by the company, with everything at room temperature. After ‘printing’, excess powder was blown away from the ‘build box’, then the parts were debound and sintered to attain final strength. Typical layer thickness was 45 m . In mass production, small compo-

nents could be spaced less than 1mm apart on a base plate.

Virtually any metallic powder that can be sintered could be employed. Following shrinkage of up to 20%, maximum density was about 95-97%, similar to that attained by MIM. The ‘ink’ in the printer is also the binder for the compact, but no details were given of its composi-tion or other properties, except that it

was sufficient to provide green strength. Build rate was about one hour per cm.

Additive Manufacturing with Metallic Powders – Applications, Opportunities and Expectations, Phil Reeves of Econolyst, UK.

A specialist AM consultant, Phil Reeves (Figure 12) provided an over-view of metal powders within the fast-growing industry. He discussed how layer manufacturing techniques had evolved from simple prototyping tools to a set of technologies now used in the manufacture of production parts.

There was a big leap from prototyp-ing to series production, jewellery being one industry already taking full advan-tage of AM capabilities. Current AM processes included laser and electron beam melting technologies and metallic 3D printing for binder-based systems. Layer manufacturing was the most common today, but EBM gave greater productivity than laser melting and 3-dimensional ‘jetting’ from ceramic heads at even higher temperatures was under development.

Six drivers for the industry were cited:

economic low-volume production•geometric freedom•increased part functionality•product personalisation•environmental sustainability•new supply chains and retail models.•Medical devices were currently the

largest market for AM. Examples of items suitable for AM included some surgical instruments made in millions and others required only in tiny num-bers. The latter group ranged from cus-tomised hearing aids in plastic to dental implants in solid gold. Another produc-tion example was the arm holding the large video screen in each first-class seat in the latest Boeing airliners.

Reeves claimed to have looked at more than 280 possible AM products in the last nine years, although 906 others were NOT suitable. In 2013, at least US$350 million would be spent on R&D, and the total AM market would rise spectacularly from US$2.2 billion in 2012 to an expected US$6.5 billion in 2020. Most of the production costs went on processing, so products were relatively price insensitive where materials were concerned.

Figure 12: Phil Reeves, specialist consultant of Econolyst, UK. (Copyright © Kenneth JA Brookes 2013)

Figure 11: Phase 3: new AM design samples.