additive manufacturing: what’s happening and where are we...

Additive Manufacturing: What’s happening and where are we going with printing in the third dimension?

Additive Manufacturing: What’s happening and where are we going with printing in the third dimension?

By Neil Hopkinson, Reader in Additive Manufacturing, Loughborough University

October 2010 http://www.becta.org.uk page 1 of 22© Becta 2010 Not protectively marked

Becta | Additive Manufacturing: What’s happening and where are we going with printing in the third dimension?

Biography

Neil is a Reader in Additive Manufacturing and Senior Enterprise Fellow at Loughborough University, UK. To date he has secured over £3m of research funding from government and industry. He has been involved full-time in Additive Manufacturing since embarking on his PhD in Rapid Tooling in 1996, his current work focuses on Additive Manufacturing processes and materials. Neil’s work has been recognised internationally including an award by the American SME for Breakthrough Technology 2009. He is the lead editor of the world’s first book on the subject of Rapid Manufacturing

and has over 120 publications including papers, articles and patents. Neil was a visiting lecturer at the University of Queensland and is a Visiting Adjunct Professor at the University of Louisville. He sits on various technical international panels and has been an invited and keynote speaker at numerous international events. In 2007 Neil was voted by the readership of TCT magazine as being one of the top 25 most influential people in the rapid product development industry globally.



Introduction

Additive Manufacturing (AM) is the term given to a group of technologies that are capable of creating physical objects from computer aided design (CAD) files by incrementally adding material such that the objects “grow” from nothing to completion. Most of today’s AM technologies start with a CAD solid model which is sliced into thin layers. Each layer comprises a 2D cross section profile of the part which is then made layer by layer. Different technologies use different methods and materials to create objects, ranging from lasers melting metal powder through to inkjet heads printing photo-curable resins.

AM is a nascent technology area with the first recognised commercial machines being sold in the late 1980’s. However the concept of making objects in an additive approach is hardly new – consider how the pyramids in Egypt were produced. The automated approach to creating objects from CAD files in the additive manner that AM allows is beginning to have a profound effect on how objects are made. Almost all manufactured objects that we see today are made with some form of tooling at some point – parts may be machined using a cutting tool or parts may be formed from a moulding tool. The use of tooling imposes numerous restrictions such as design limitations, restrictive costs to prepare for manufacture and the need to create products at a single location prior to being shipped globally. AM technologies invariably require no tooling to create parts and this profoundly affects how products can be designed, tailored, made, distributed etc. Figure 1 shows an example of the design of an automotive housing manufactured by traditional casting and machining on the top with a version design for AM on the bottom. The design on the bottom is able to use 40% less material than the design on the top and AM allows the design to employ curved channels rather than straight line drilled channels that are needed by traditional processes.

Figure 1. Design for AM product compared with design for traditionally manufactured part

Benefits such as design freedom and speed of one-off part manufacture add value toproducts that can be made by AM processes. This addition of value, coupled with high costs of technology development have meant that equipment, material



and maintenance costs have been high. These high costs have often restricted ownership of AM equipment to large organisations or organisations dedicated to supplying parts made by AM. However reductions in cost over the years have allowed institutions with smaller budgets to adopt the technologies. The Fused Deposition Modelling process is an example of an AM process that has been developed to aim at the low cost end of the market with machines being launched in 2009 with a list price of $14,900 (Wohlers 2009). The education sector is a good example where the technology is being adopted, albeit at the lower price point end of the market. Within the education sector, the processes are being used in an increasing number of Design and Technology departments allowing students to create physical models of parts that they have designed, though CAD solid modelling packages are an important prerequisite. Some school projects have involved the building and use of low end open source AM systems while other projects have involved the production of parts on more advanced commercially manufactured systems. Beyond Design and Technology, the option to make physical objects in this way has applications in teaching throughout the curriculum.

Terminology

The versatility of AM processes has enabled them to expand into a myriad of different applications and consequently a number of different names for the processes and the way they are used has evolved. Rapid Prototyping, Rapid Tooling, Rapid Manufacturing, 3D Printing, Solid Freeform Fabrication, Direct Digital Manufacturing and Additive Layer Manufacturing are among the many names that have been coined. This range of expression can be overwhelming to newcomers to the technology (even industry “dinosaurs”* have trouble keeping up) so some key terminology is explained below.

Rapid Prototyping (RP) was the first widely used expression to describe AM technologies. The first process to be commercialised was stereolithography by Californian company 3D Systems. Stereolithography proved to be particularly well suited to the creation of physical prototypes which helped to slash development cycles for new products. Manufacturing organisations were able to realise significant benefits from shorter product development times and so the market for Rapid Prototyping machines was able to flourish. Even today, two decades after stereolithography was commercially available, the majority of applications for AM machines is in the creation of prototypes of one form or another (Wohlers 2009).

The benefits of RP have spread up the product development chain to include the manufacture of mould tooling using AM processes. Technology improvements such as a wider range of more robust materials plus improved accuracy have enabled organisations to use AM processes to quickly make tooling of various types leading to the expression “Rapid Tooling” (RT). Today RT encompasses the manufacture of mould tools ranging from moulds for the creation of short series of



prototypes through to the creation of production injection mould tooling to manufacture millions of products. RT processes included direct approaches where the mould tool is created on the AM machine and indirect approaches where an AM machine is used to create a master pattern from which a tool is cast and then parts are made.

As the technology improved further and confidence in the performance of parts grew, in the late 1990’s and early 2000’s AM technologies began to be used to create end use products, leading to the term Rapid Manufacturing (RM) (Hopkinson et al, 2005). The fact that AM technologies grew initially on their ability to create prototypes quickly has often meant that industry users perceive the processes as only being capable of making prototypes. Widely held perceptions are that the parts made are not robust or reliable enough to be used as end use products. Also the speed of part production compared with, for example injection moulding, often means that people can not picture the use of the technology for the manufacture of end use products. However RM applications are growing quickly and industry experts predict that RM will become the most common way in which AM technologies are used in future (Wohlers 2009).

Probably the biggest unique selling point of AM technologies is their ability to manufacture geometries that can not be achieved by conventional processes. Figure 2 shows an example of a complex sculpture made by the SLS process. The geometric freedom offered by AM led to the term “Solid Freeform Fabrication” (SFF) which is probably the best technical description of the processes but regrettably somewhat unwieldy for mass adoption. SFF can broadly be seen as a synonym for AM but the expression “freeform” does help to convey the befit of geometry freedom.



Figure 2. Complex sculpture enabled by AM technology (http://www.georgehart.com/sculpture/mermaids-delight.html)

As most of today’s processes create parts layer by layer, each layer can be thought of in many respects as similar to printing. Instead of printing text on a page, the processes “print” the 2D profile of a part under construction so an analogy with printing is clear. The fact that the process repeats with subsequent “prints” to create 3D parts instead of 2D profiles has led to the term 3D Printing being used to describe the processes. Today 3D Printing is considered mainly as a reference to low cost machines or those that employ print heads usually for prototyping purposes but the user friendly nature of the expression might mean that this becomes the de facto expression for all the process currently referred to as AM.


http://www.georgehart.com/sculpture/mermaids-delight.html


Generic process sequence

For the vast majority of AM processes there is a standard generic sequence that is employed to create parts. This is shown in Table 1.

Process step Description

Convert CAD model to STL format CAD model is converted into STL format that represents the surface of the part by many triangles (see Figure 3).

Orient part (s) Operator uses experience to select best orientation for example to minimise build time or to achieve tolerances on key dimensions .

Generate supports if required Software normally automatically generates supports where needed, however experienced operators can usually edit these to for example to minimise need for manual support removal during post-processing. Figure 4 shows the design of a part with supports in place.

Create slice files Software generates the 2D profile description of each layer of the part plus supports to be made.

Fabricate part plus supports 2D profiles are sent to the machine to drive part creation, for example by controlling mirrors that allow lasers to scan across a powder bed to sinter/fuse powder where required.

Post-process When parts have been fabricated they need to be cleaned, for example to remove excess unfused powder or to remove support structures. Further work such as sanding, infiltration, painting or electroplating may also be required depending on the process used and the intended application for the part.

Table 1. Generic process sequence for AM technologies



Figure 3. CAD model of a cylinder converted to STL format

Figure 4. Part design (shown in grey) with supports required (shown in red)



Key technologies

Since the inception of AM in the late 1980’s a range of different processes and variations on these processes have emerged. Some of the key technologies are described below. In each case the way in which the process works is briefly described, this helps to give an appreciation of the strengths and weaknesses of each process.

Stereolithography was developed in the 1980’s by Chuck Hull who founded the industry’s first recognised company, 3D Systems in Valencia California. The first machines were sold in the late 1980’s and early 1990’s. The process uses an ultraviolet laser to solidify photo-curable resins to create parts in thermosetting polymers based on acrylate and epoxy chemistries. Figure 5 shows an image of the process comprising a vat of resin with a build platform and laser/optics system. The process starts by locating the horizontal build platform just below the surface of the resin. The laser then scans a 2D profile, curing required sections of the surface of the resin and adhering the cured resin to the platform. The platform then drops by the height of one layer of the part (typically ~ 0.1mm) and the next layer is scanned and adheres to the cured material below. The process continues until all layers have been cured at which point the platform can be raised from the vat and the platform removed from the machine. The parts can then be removed from the platform and supports removed from the part. This is often followed by cleaning and post-curing to ensure that the part does not have any uncured material on its surface. The main strengths of stereolithography are the accuracy and fine feature resolution with which parts can be made. However the use of photo-curable resins often results in poor stability over time with parts prone to moisture absorption and continued curing leading to warpage and changes in part properties. The resin itself also requires special care during handling/use and the geometry capability can be hindered by the need for supports. Machine and material costs for stereolithography are currently high with machines costing in the region of £50,000 to £500,00 and materials typically around £100 to £140 per Kg. Consequently machine users tend to be large organisations or those dedicated to supplying high accuracy AM parts.



Figure 5. Stereolithography Process (Rapid Manufacturing, an Industrial Revolution for the Digital Age, Wiley Publishing, 2006)

Powder bed sintering has become a widely adopted approach to creating end use parts by AM. All powder bed sintering processes work by depositing powder onto a platform. A laser then scans a 2D profile across the powder’s surface in a similar manner to that employed by stereolithography to fuse together adjacent particles and create each 2D profile. The platform then drops by the thickness of a layer (typically ~0.1mm) and a fresh layer of powder is deposited on the surface of the previous layer and the laser again scans to fuse particles to each other and to sintered material in the previous layer where required. When all layers have been built and the machine has cooled sufficiently the platform can be taken from the machine and loose powder removed, for example by bead blasting, to reveal the part or parts. The first powder bed sintering machines were sold in the early 1990’s by DTM corporation, a spin out company from the University of Texas at Austin. DTM named and trademarked their process as “Selective Laser Sintering” (SLS). Figure 6 shows a schematic of the SLS process. SLS has the benefit of being able to produce parts without support structures as the underlying powder beneath overhanging features prevents sagging, this allows particularly complex structures to be built as removal of powder is simpler than removing support structures. The German



company EOS GmbH also supplies machines that produce sintered polymer parts in much the same way. As with stereolithography machine prices are high, in the region of £100,000 to £700,000. Materials costs tend to be lower than those for stereolithography, in the region of £30 to £80 per Kg. A number of companies sell machines that sinter or melt metal powders using lasers or electron beams. The approach is similar to that described above for polymer powders but the high stresses involved mean that metal parts need to be made with supporting structures that later need to be removed. Again machine costs are high for metal powder sintering/melting machines ranging from £200,000 to £700,000, however powders are generally cheaper ranging from £20 to £70 per Kg. The process of sintering/melting particles opens powder bed processes to a wide range of material types spanning polymers, metals and ceramics all of which tend to make parts that are stable over time. However powder handling can be problematic and even dangerous, for example when processing reactive metals in high temperature environments.



Figure 6. SLS Process (Rapid Manufacturing, an Industrial Revolution for the Digital Age, Wiley Publishing, 2006)

Fused Deposition Modelling (FDM) is perhaps the simplest AM technique to describe and demonstrate. Figure 7 shows a schematic of the FDM process. The process works by extruding liquid polymer through a nozzle that traverses to deposit a layer in a manner similar to icing a cake. The process requires at least two nozzles, one to extrude material for the part and one to extrude support material. The first layer is created by depositing support material onto a platform. The platform then drops by a layer (typically ~0.25mm) and more material is deposited. As the build progresses, each layer will normally comprise a mix of parts material and support material. When the build has completed the support material needs to be removed. Some support materials are water soluble and can be removed by placing the parts in water however non-water soluble support need to be removed physically. FDM machines are among the cheapest available ranging from around £10,000 to £200,000 although it should be noted that materials are amongst the most expensive at around £150 to £250 per Kg. The process can run in an office environment and material handing with pre-packed cartridges is straightforward. The main drawback of the process is the weakness of parts caused by poor bonding between layers, also supports are required, however water soluble supports can be easily removed.



Figure 7. FDM Process (Rapid Manufacturing, an Industrial Revolution for the Digital Age, Wiley Publishing, 2006)

3D Printing (3DP) was developed at the Massachusetts Institute of technology (MIT) and has been licensed to a number of commercial enterprises. Figure 8 shows a schematic of the 3DP process. The process uses powdered material, typically starch based, as a raw material which is deposited onto a platform in a similar manner to that used by the powder bed sintering processes. Particles are joined by depositing a binder onto required areas of the bed to form each layer of a part. The process is considerably quicker than the technologies described above as inkjet heads allows simultaneous depositing of binder rather than the sequential progress of lasers/electron beams or an extrusion nozzle. The parts produced however are considerably less robust than those produced by the processes described above. The term “3DP” has been trademarked to describe this process. Z-Corp has been selling 3DP machines since the early 1990’s, however other variations of the process, using different materials have emerged. The speed of 3DP is it’s most obvious strength although the ability to create coloured parts is also attractive for many applications. The process does not require supports which eases post-processing and provides geometry freedom but the low strength of parts means that fine features tend to break easily and the parts can only be used for applications with minimal load, often for visualisation only. Machine costs are comparatively low and can often be purchased from £15,000 to £50,000. Material costs include powder which is cheap and binder which is expensive, combining them typically works out at around £35 per Kg of final part.



Figure 8. 3DP Process (Rapid Manufacturing, an Industrial Revolution for the Digital Age, Wiley Publishing, 2006)

The ability to make parts quickly using inkjet technology has led to different organisations developing and commercialising resin jetting processes. These processes use inkjet technology to jet photo-curable resins in the liquid state onto a platform, a UV light source immediately follows and the resin is quickly solidified using chemistry similar to that employed by stereolithography. The platform then drops by one layer (down to 0.016mm) and the next layer of material is printed and cured. The processes generally deposit at least two materials, one to create the part and another to act as a support. 3D Systems commercialised machines of this type in the early 2000’s and they employ a wax based support structure that is melted away after the build is complete. Objet from Israel also commercialised machines in the early 2000’s and they employ a second UV curable resin, producing a softer material than that for the main part as a support. This support material is then removed for example by jetting water. As these processes employ support material that is different to the part material they are invariably able to create extremely complex geometries. Process speed is a key attraction using jetted resin as is feature resolution. The fact that all of the material in the part needs to pass through a print orifice means that the process is generally best suited to small parts. As with stereolithography, the use of a curing resin tends to lead to long term instability issues such as changes in mechanical properties over time. Machine prices for these systems tend to be relatively low at around £25,000 to £60,000 however materials costs are very high ranging from around £80 to £250 per Kg.

A further development in process architecture to increase processing speed has been developed in resin flashing processes. These processes selectively cure resin



on a plane using UV energy and chemistry similar to that for stereolithography and the resin jetting processes. The UV energy supply is controlled using Digital Multi- Mirror Device (DMD) technology, essentially an array of mirrors that can be in an “on” or “off” position. By shining UV light at a mirror and controlling each micromirror’s position then UV energy can be applied in a suitable 2D cross section to solidify resin where required. The German company Invisiontec first commercialised this approach with their “Perfactory” process (see Figure 9). Originally the process built parts up-side down however a more conventional approach using a resin vat as is used in stereolithography is now employed. 3D Systems have also commercialised a system that flashes across a surface, they call this the “V-Flash” process. This process does not use a vat of resin to contain raw material and build parts, instead thin films of resin are applied to the surface of the build platform for the first layer and to the last layer build for subsequent layers. The resin is then selectively cured to bond to the platform or previous layers. Both the Perfactory and V-Flash processes require support structures to be built in the same material as the part which require post-build removal and restrict design freedoms. The strengths and weakness of parts made by resin flashing methods are similar to those for stereolithography and resin jetting but process speed is quick and the most suitable parts tend to be very small. The lowest price machines of this type cost around £20,00 to £40,000 region with larger machines costing more however materials costs can be very high at around £350 per Kg.



Figure 9. Perfactory Process (Rapid Manufacturing, an Industrial Revolution for the Digital Age, Wiley Publishing, 2006)



Evolution of the technology and its applications

As with most new technologies the early adopters were large corporations that could afford to take the risk of venturing into this new area of manufacturing. However as costs reduced with increasing sales volumes then fast followers began to engage in the industry. While the obvious sectors of automotive, aerospace and consumer goods were key users it became apparent that a very broad range of end users and applications could benefit from AM. Rather than finding one or two “killer” applications the industry diverged into a plethora of different sectors and applications. As the industry matured in the late 90’s and 00’s it appeared that processes fell broadly into two categories, the first being low cost, low part performance “3D Printing” machines and the second being high cost, high part performance modellers and production machines. At times the boundaries between these categories has become blurred however a distinct market for low cost machines to make low end, limited functionality parts has evolved as has a market for higher cost machines to make parts with high qualities such a material properties or accuracy and resolution.

The overall market for AM in terms of products and services has grown from an estimated $485M in 2002 (Wohlers 2003) to $1.183B in 2008 (Wohlers 2009). Market growth in terms of numbers of machine sales has been greatest for the low cost machines. Unit sales of low cost machines was estimated to be ~500 in 2001, yet a mere 7 years later in 2008 sales were estimated to have multiplied almost eight times to just under 4000 units (Wohlers 2009). These processes have seen significant improvements in the quality or capabilities of parts produced, for example 3D Printing using colour with increasing resolution has opened applications that did not exist before colour was an option. Often the improvements of parts from low end machines have been to a point or even beyond a point where ten years ago the parts would have been considered high quality, for example FDM parts now have considerably finer feature resolution than they offered before.

The growth in numbers of machine sales of higher end machines has been less impressive on first sight than those for low end machines. Total sales of all AM machines in 2001 were just under 1300 (Wohlers 2003) and in 2008 they were just over 5,000 but the majority of this increase in unit sales has been for the lower end machines (Wohlers 2009). However the value of machine sales for higher cost technologies has been impressive. It is important to note that the growth in numbers of low end machines sales has been enabled by significant reductions in sales prices of these machines. Higher end machines are often sold with various options such as thermal control systems in powder bed sintering systems that increase process repeatability which is key for many manufacturing applications but also means that machine costs and revenues to suppliers are high.



Average machine costs have come down, this is partly explained by growth of sales in the low end market. Costs for materials, consumables and maintenance have generally reduced though not as markedly as those for machines. It appears that the “razor blade” business model of selling machines at low prices to make money on materials after machine sales has become more prevalent. There is no question that reductions in machine costs have opened to the door for end users such as schools and colleges however the ongoing costs of materials and maintenance need to factored in when organisations invest in the technology.

While machine costs have come down, improvements in capabilities have also opened the door to new applications. For example, parts made by powder bed sintering processes are now routinely used as production parts on military and civilian aircraft.

AM’s versatility in terms of providing solutions across a wide rang of sectors, including many applications and products that had never existed prior to AM has helped the industry to grow at an impressive rate. Detailed data on market size are proving increasingly difficult to obtain but it is widely accepted that the industry has grown at more than a double digit rates for most years since its birth roughly twenty years ago. The breadth of applications has not made the industry immune to large dips in the global economy such as those from the early and late 00’s.

Future possibilities

Detailed predictions about the long term applications of new technologies are notoriously difficult to provide with any accuracy and AM has thus far proved to be no exception. A number of people have made long term predictions that versions of AM machines will be as commonplace as, for example a micro-wave oven and that people will be able to download items from the web and print them at home. This notion formed a central role in Neal Stephenson’s science fiction novel “The Diamond Age”. There are organisations actively working towards open source machines that can print parts in almost any material. Parts, albeit of inferior quality when compared to commercially supplied offerings, have been made in materials such as ice or chocolate, however the dream of a “matter compiler” as described by Neal Stephenson is still some way away.

Short term growth of the industry can be predicted more readily by extrapolation of recent industry figures and trends, coupled perhaps with knowledge of particular sectors or applications that are ready for commercialisation. The Wohlers annual state of the industry report is widely recognised as the “go to” text for predictions of how, where and how big the AM industry will be in the next 2-5 years.

Predicting the growth of AM in the next five to ten years is particularly problematic. There have been many instances in the industry where an application



has seemingly come from nothing to maturity in the space of five to ten years. For example in the mid 1990’s the notion of making domestic lamp shades using AM would have seemed a highly unlikely application to most people. Ten years later the industry for such products had generated keen competition and sales volumes in the thousands.

A return to the analogy of AM with 2D printing can provide a useful framework with which to consider the future of the technology in the next five to 10 years. The inkjet industry shares a great deal of common language with AM when it comes to issues such as competing technologies, business drivers, business models, IP generation and potential for growth.

The production of 2D information on a 2D surface goes back many millennia. The production of 2D information on the page also goes back along way in time. However until the advent of the Guttenberg press this always had to be performed manually and so scale up was limited. The Gutenberg press changed this in much the same way that the industrial revolution allowed the automated and thus high volume creation of 3D products. It is useful to think of the printing press as a 2D analogy for the injection moulding tool. Production of the printed page or the 3D object in high volumes at low costs has been made possible but they do incur initial costs of tooling and limited ability to tailor products. Inkjet printing has since provided an alternative to the printing press for the 2D industry especially for small volumes. Inkjet has allowed automated high quality replication of information on to a suitable blank surface whereby each print may differ from the next. Over time the inkjet industry has spread to cover a variety of sectors and is now ubiquitous in examples such as printed use by dates on food, drink, pharmaceutical etc. The fact that inkjet technology has made it into the home perhaps gives some credence to the notion of a domestic matter complier in the fullness of time. The examples of use of inkjet technology described above spilt into two obvious categories – end user driven (desktop printers) and industry driven (labelling etc).

The world of AM is already seeing examples of end user driven application such as Figureprints where computer games players developed their own avatars and can then have 3D models of them printed using 3D Printing. Shapeways is another venture that seeks to exploit the possibilities opened by AM, allowing members of the public to upload their designs that can then be ordered by anyone, printed and delivered. The end user driven sector is currently restricted to aesthetic parts with limited functionality. However as user confidence grows then it is likely that market for parts with greater functionality are likely to appear. There has already been work to create functional products such as sports footwear using AM technology and the sports sector might be an early area for the development of high added value, personalised products made using AM.



Increased user involvement in the design and production of parts does bring questions of legal issues. For example what happens if a user designs their own component to be used in a device, has the component made by a supplier and then the component fails? Is the designer/user at fault for producing an inadequate design or choosing an inappropriate material or process to make the part? Or is the manufacturer of the part at fault? Further to this there is an analogy to be had with the music industry, how easy is it to control users obtaining CAD files of parts and then printing them. Even if the original CAD file can be protected it would be possible for someone to reverse engineer a product and then send this file by email to various people who can then print their own copy of the part.

The early growth of inkjet is likely to provide a useful guide for the future growth of AM in industry. Industrial application of inkjet was helped by the technologies flexibility perhaps best exemplified by the ability to print sell-by dates on food packaging. Inkjet’s ability to provide this solution that protected the end user led to such labelling becoming mandatory. It therefore makes sense to consider where AM might provide hitherto impossible or impractical solutions that improve public health and safety to such an extent that the solution becomes mandatory. One example may be in providing information for the visually impaired to assist in getting out of building in emergencies such as fire. Most buildings are unique so creating a 3D map of each building by conventional means is impractical. However AM has proved itself as an adept method to print 3D models of buildings and these could become mandatory for health and safety reasons. Add to this, the obvious day to day benefit to the visually impaired of being able to independently find their way around a new building.

Another benefit shared by 2D inkjet and 3D AM is the potential for distributed production. The printing press and injection mould tool force organisations to print or mould their product in a single, or small number of, location(s) and then ship the product to the end users via various distribution channels. AM will open the door for manufacture at or near the point of end use. The concept of 3D Kinkos where one can download a product and have it manufactured at a local AM shop is perhaps the first step towards the ultimate dream of the domestic matter compiler and again, it has the ability to build on tried and tested business models from the 2D world. A prime example of this might be in the supply of after sales services. If one breaks a product such as a door handle on a washing machine the current means to supply a replacement is to have a spare part sent from a central storage location. The costs of storage and supply logistics of parts for products as complex as washing machines are not trivial and these could be simplified considerably by virtual storage of the CAD file for the part and manufacture of the part where and when it is required. The environmental benefits in terms of reduced carbon footprint for such an approach could be enormous. The idea of supply of spare parts in this way has already been considered by NASA who have



assessed the possibility of manufacture of replacement parts in micro-gravity using FDM (Crockett et al, 1999).

Within the education sector, reductions in costs of equipment and materials have allowed the processes to be taken on in an increasing number of educational institutions. Machines are predominantly used in Design and Technology departments allowing students to create physical models of parts that they have designed. It is important to note that the availability of CAD solid modelling packages are an important pre-requisite to created the model which AM can then make and that such CAD packages are becoming commonplace in schools. When interviewing ‘A’ level students who are applying for engineering courses they frequently (and enthusiastically) describe how they have used AM in Design and Technology projects. Some schools have acquired and built open source AM machines such as the “Fab@Home” and “RepRap” systems that can be assembled using information provided on the web. While the parts produced on these open source systems tend to be very basic, the process of building a machine will provide invaluable hands on experience for tomorrow’s engineers. However some school projects have involved the production of parts on commercially available systems. At the more ambitious/advanced end of the scale this has included teams of pupils using AM parts to build competitive solar powered vehicles.

However the breadth of possibilities with AM is such that the technology should have a positive impact in education beyond Design and Technology. Most academic subjects will, over the course of time and enabled by word of mouth and proactive staff and students, benefit from the ability to make physical objects. For example, in the teaching of Geography it is easy to imagine that printing of 3D maps of areas under study will help students to recognise physical geographic formations and to understand how they have been shaped. In Biology it will make sense to print the skeletons of animals being studied. In History it will be possible to print physical copies of artefacts used by our ancestors. In all these cases the subjects under study will “come alive” by the easy and affordable creation of physical models. It is often said that a picture is worth a thousand words, it is likely to become the case that a physical model is worth a hundred pictures. Perhaps the key driver and enabler for spreading AM technologies within education will be the physical presence of objects that had not been seen in schools and colleges before. A 3D Printed landform in a Geography classroom only needs to be seen by a History teacher to provide the catalyst for the technology to be used in History classes. This should easily set off a chain reaction that spreads to different academic subjects.

The use of AM technologies as teaching tools across the curriculum is going to evolve over time, however this process will be slowed by a number of factors. Firstly the machines and costs of running them are high although costs are reducing at an impressive rate. The trend towards simpler machines will help the spread within education, they will not require high levels of skill to run. It will be appreciated



that printing 3D parts is not going to be as quick as printing 2D information on pages however the value of a 3D printed object will be such that the wait for an overnight 3D print will not be considered a major inconvenience. Many of the processes generate waste material and use hazardous materials however this is already the case for other processes currently found in Design and Technology departments. For this reason it is likely that AM machines will continue to be located in Design and Technology departments although the parts made will spread to all corners of education.

Review

AM technologies have come a long way in a short time and their future looks bright, especially for use as production machines rather than just for prototypes. This is likely to lead to the generation of new types of products that were economically unviable or geometrically impossible to make in the past. Personalised products ranging from decorative figurines/avatars through to functional devices such as foot orthoses to treat or prevent musculoskeletal issues are likely to become common place. In schools the use of parts made with AM technologies will break out from Design and Technology and be another one of many useful teaching aids especially where a purpose made physical object helps a subject to come alive. In many respects the growth of AM technologies in schools will be the inverse of that in industry. In industry the shift will be away from visual aids to functional products but in schools, the shift will be from functional parts/prototypes in Design and Technology to visual and tactile aids for all subjects.

* At the annual conference for users of 3D System’s equipment, awards are given to people in recognition of their continued contribution to the industry. These awards are in the form of a printed dinosaur.

References

Crockett, Petersen and Cooper, 1999, Fused Deposition in Microgravity, Proceedings of the Solid Freeform Fabrication Symposium, pp 671-678, Austin, Texas, August 9- 11, 1999

Hopkinson, N., Hague, R.M.J. and Dickens, P.M., 2005, Rapid Manufacturing an Industrial Revolution for the Digital Age, John Wiley and Sons Ltd, ISBN 13 978-0- 470-01613-8

Wohlers 2009, State of the Industry, Annual Worldwide Progress Report, Wohlers Associates, USA, 2009

Wohlers 2003, Rapid Prototyping Tooling and Manufacturing Annual State of the Industry Report, Wohlers Associates, USA, 2003


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