An Evolution in Construction by Ross Overfield-Collins

“like Darwinian novation, it is therefore an evolutionary process that robotics will become commonplace in construction methods” PAGE 16

APRIL 2010

CONSTRUCTION AND THE BUILT ENVIRONMENT

Ross Overfield-Collins

Evolution in Construction An Exploratory Review of Mega Scale Rapid Prototyping

Ross Overfield-Colli

Ross Overfield-Collins

â&#x20AC;&#x153;I hereby declare that this dissertation is as a result of my own independent endeavours and investigation, except where I have indicated my indebtedness to other sources. I further declare that this dissertation has not been accepted in substance for any other degree, nor is it being submitted currently for any other degree. Ross Overfield-Collins

18th April 2010

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ii.

Ross Overfield-Collins

Acknowledgements It is with great appreciation that I would like to thank Enrico Dini of D-Shape, Dr. Behrokh Khoshnevis of Contour Crafting and all those who contributed from Loughborough University for their valuable information within this project. My special thanks to my supervisor, Dr. Edin Moosavi for all his help and guidance throughout this work, has steered me onto the correct path many a time. I am also grateful to Terry Wohler and Wohlerâ&#x20AC;&#x2122;s Associates for their patience, expertise and product sector knowledge, without which I would not have been able to produce this. And finally I would like to thank all of those family and friends who read and re-read this project; who encouraged me and gave support throughout the whole course. I am eternally grateful.

iii.

Ross Overfield-Collins

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4 3

list of tables list of figures

introduction 1 What is Rapid Prototyping? The Ideology

Reason for Aims and Limitations of Research quality 7

8 8

geometric freedom mass customisation materials costs end users Aim Objectives

1.1

1.2 1.3 1.3.1 1.3.2 1.3.3 1.3.4 1.3.5 1.3.6 1.4 1.5

research method 2 Methodolo Methodology Structure of the Dissertation

2.1 2.2

literature review 3

The state-of-the-art the use of robotics in other industries 15 robotics in construction 16 State-of-the-art-RP technology materials used in rapid prototyping 18 the impact rapid prototyping has had on the industry Research into Printing a Building

3.1 3.1.1 3.1.2 3.2 3.2.1 3.2.2 3.3

4 case studies 4.1 4.2 4.3 4.3.1

Case study: d-足shape interview with enrico dini

5 discussion 5.1 5.2 5.3 5.3.1 5.3.2 5.4 5.5 5.5.1 5.6 5.6.1 5.6.2 5.7 5.7.1 5.7.2 5.7.3 5.7.4 5.8

23 26

Case study: university of southern california Case study: freeform engineering

Drivers For Change Sustsainablility

37 39

I nvestment investment in the construction industry

investment in mega scale RP Software Designing the Future archineering Materials, Methods and Integration

40 40 42

integ integrating two materials 42 the operating mechanisms Acting on Drivers For Change 46 quality-足cost correlation 46 speed 47 quality 48 design freedom T he Future of Mega Scale RP in Construction 50

6 conclusion

: the direction this technology is heading

Bibliography Appendix

31 34

52 55

Ross Overfield-Collins

List of Tables 3.1. Summary of Rapid Manufacturing Techniques 3.2. Summary of Rapid Manufacturing Materials 4.1. Possibilities for Processes for Creating FreeForm Structures (Courtesy of Loughborough University)

List of Figures 1.1. Illustrated geometrical freeform (image courtesy of InGlass) 2.1. Research methodology, Soft Systems Model (modified from Checkland, 1990) 3.1. Non-Cartesian welding robot (image courtesy of Motorman inc.) 3.2. Corus automation (image courtesy of Corus Group) 3.3. Illustrated 3D process (image courtesy of R.A. Buswell) 4.1. Illustrated Contour Crafting process (image courtesy of CRAFT) 4.2. Estimated research schedule for Contour Crafting (image courtesy of CRAFT) 4.3. Contour Crafting wall constructed in collaboration with Caerpillar (i mage courtesy of CRAFT) 4.4. Schematic representation of the CC trowel operation (image courtesy of Kwon, 2002) 4.5. Reinforcement within the extrudate material (image courtesy of Kwon, 2002) 4.8. Panels designed and printed in conjunction with FreeForm construction (image courtesy of Loughborough University) 4.7. Multi-service trunking (image courtesy of I3CON) 4.8. Drawings, details and workshop images of Villla Rocce (images courtesy of Enrico Dini and Faan Studios) 4.9. Inorganic binder in operation (image courtesy of Enrico Dini) 4.10. Hypodermic needle illustrating the surface tension in a droplet (image courtesy of WhiteNeedles.co.uk) 5.1. Free-Electricity generator (image courtesy of Innovative Technologies Ltd.) 5.2. Eda Yetisâ&#x20AC;&#x2122; Hurricane House, produced using Selective Laser Sintering 5.3. Artists impression of topological optimisation (image courtesy of Loughborough University) 5.4. Fused Deposition process (images courtesy of Trumpf and Hopkinson, 2006) 5.5. Artist impression of a multi-axis robotic arm using Contour Crafting (image courtesy of CRAFT) 5.6. Hexapod system (image courtesy of NIST) 5.7. Dimensional accuracy graph (image courtesy of Urbanska-Gaewska, 2008) 5.8. Cost comparison (courtesy of R.A. Buswell) 5.9. Speed comparison (courtesy of R.A. Buswell)

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1. Introduction: Background to the Topic

Ross Overfield-Collins

freefo const rm ructio n

3D pr inti

RESEARCH METHOD “This research is primarily focused on investigating variables, through which hypotheses may be generated, for future research. It could also be categorized alongside predictive types of research however the empirical approach required to achieve the objectives requires a more exploratory review of the data.”

semi- solid paste s

Ross Overfield-Collins

2. Research Method 2.1. Methodology This research is primarily focused on investigating variables, through which hypotheses may be generated, for future research. It could also be categorized alongside predictive types of research however the empirical approach needed to achieve the objectives requires a more exploratory review of the data. The theoretical soft systems model (SSM, Fig.2.1) of Checkland and Scholes (1990) will loosely be adopted whereby both theory and practice will be assessed separately but combined in a formulative and summaritive evaluation of the findings.

Fig.2.1: The Modeling Process (developed from Taha 1971; Checkland 1990)

Ross Overfield-Collins

To achieve the research objective a combination of research methods was adopted. Methods include interviews, a desk study, and case study analysis. Both the desktop study and case study analysis use a positvism approach, whereby facts and causality are the primary focus of the documents (Fellows, 2008), these sources can provide the insight into the ideas behind mega scale rapid prototyping. Case studies can also be interpretivist, whereas interviews are, predominantly the latter, therefore all three approaches to the research should provide a well-rounded and unbiased view of the subject. Similarly both qualitative and quantative approaches will be sought for this research. Qualitative being that of descriptive based interpretation, of peopleâ&#x20AC;&#x2122;s views around the specific subject matter; but also deciphering any bias of that information, to develop a coherent and comprehensive iteration.

It should be noted that by undertaking

unstructured interviews from a wide spectrum of participantâ&#x20AC;&#x2122;s perspectives an in-depth view of the subject was ascertained, which will latterly be communicated as part of this study. Quantative data is the collection of previous work and theories; this systematic analysis, will allow, according to Morse (1994) a saturation of information whereby a formulative and summaritive assessment can be drawn.

2.2. Structure of the Dissertation The following chapters will address the state-of-the-art technologies associated with Rapid Prototyping and Rapid Manufacture.

The literature review in particular will

highlight the research undertaken by specialist groups with an interest in mega scale construction, upon which, will provide a precedent for the processes, shown by the case studies in chapter 4. Minutes of the numerous meetings will not be included herein (with the exception of DShape analysis), however the findings will be discussed in the discussion section (chapter 5), along with the phenomena found by evaluating the comparable case studies of those research groups actively interested in mega scale RP construction. These will thence be summarised (chapter 6) and presented in a clear and logical manner, to highlight the clear direction this technology is advancing towards.

Literature

Ross Overfield-Collins

3. Literature Review 3.1. The State-Of-The-Art State of the art is defined in the Dictionary of the English Language (2000) as being â&#x20AC;&#x153;the highest level of development, as of a device, technique, or scientific field, achieved at a particular timeâ&#x20AC;?. In relation to Rapid Manufacture it would be the most recent processes and technology known to be in existence at present.

3.1.1. The Use of Robotics in Other Industries In other industries, robots are commonplace to produce complex and intricate tasks, for instance the car manufacturing industry has used robots to weld, maneuver, machine and process components for decades. They recognised early on that automated methods can often achieve a finish which is higher in quality; consistently producing results faster, more efficiently, more accurately and without stopping (Expo, 2009). Consequently

complimenting

any

weaknesses

humans may face on a manufacturing line. This is particularly true of the engineering industry where robotic and Computer Numeric Control (CNC) Fig. 3.1: The 7-Axis, VA1400 Arc welding robot can offer improved access into extremely tight spaces (Image courtesy of Motoman Inc.)

machines are now common place, producing engine blocks, rig drilling equipment, aeronautic parts etc.

using simple 3-axis machines (x,y,z directional planes), up to 7-axis robotic arms (Fig.3.1).

3.1.2. Robotics in Construction The attractive prospect of efficiency, and reduced energy consumption has not bypassed the construction industry. It is now with great virility and regularity on large construction sites to see wall crawlers fixing facades to a frame, lifting mechanisms and generally more mechanised operations. Yet with more on site robotics being used to increase production, it is off-site manufacture that is dominating Modern Methods of Construction (MMC).

With many companies being able to produce accurate, pre-

designed, pre-fabricated sections of building that can be erected in a matter of days.

Ross Overfield-Collins

This reduces on-site costs, but drastically increases costs off-site during the design stages (Totten, 2008). Corus, the leading British steel manufacturer uses robotic welders to fabricate its steel sections (Fig.3.2)

which

simply

bolt

together

on-site,

similarly Huuf houses use a robotic welding and machining off-site. However timber manufactured panels

can

also

produced

using

off-site

manufacture; Kingspan has produced structurally insulated panels (SIPs) with great effect in Britain’s first

zero

carbon

house,

the

aptly

named

‘Lighthouse’ in BRE’s innovation park.

Fig. 3.2 Automation at the Shotton Works; Corus Factory (Construction Dept.) (images courtesy of Corus Group).

The BRE have stated that by using factory automation these high performing buildings were only possible because of the highly automated processes used in production. So like Darwinian novation, it is therefore proposed that like an evolutionary process; robotics will become commonplace in construction methods, and Rapid Prototyping may have the potential to cause this paradigm shift towards automated construction.

3.2. State-Of-The-Art RP Technology Commercial additive fabrication emerged in 1987 with the introduction of the SLA-1 stereolithography (SLA) machine by 3D Systems, which set the precedence for making physical 3D models from computer generated models (3D-Systems, 2009). Today there are numerous methods to transform a computer aided model into a reality, including material reducing methods like CNC machining, but none have the flexibility and geometrical freedom of material additive methods (Jacobs, 1992). Figure 3.3 shows a typical 3D printing method, step-by-step, it highlights the necessity to ‘slice’ the 3 dimensional model, back into 2.5 dimensions; two and a half dimensions are the result of the minimum thickness that a layer can produce, it is almost in limbo, as it is too narrow to be useful as an object yet it is still has a physical dimension, albeit on a micro level. Then sending the individual slices to the Computer-Aided Manufacturing (CAM) software for analysing and registering the specific extrusion/sintering path of each layer.

Ross Overfield-Collins

Fig. 3.3: Representation of the 3D Printing Process in Stages (Image courtesy of R.A Buswell et al., Freeform Construction: Mega-scale Rapid Manufacturing for Construction)

By far the most used technology of this kind and rapid manufacture of late is stereolithography and it variants. Above is the process 3D printing, often wrongly classified as being the method which encompasses all the processes involved in additive fabrication, it is classified by Wholers Associates as being a completely different system altogether (Wohlers, 2008), separate from other major processes that include; Fused Deposition Modeling; Selective Laser Sintering; Aerosol Jetting and Semi-Solid Freeform Construction, many of which can be seen in an overview of all the current processes in table 3.1.

Ross Overfield-Collins

In a recent interview, Terry Wohlers also goes on to describe that high precision manufacturing is indispensible for using these techniques commercially (2010). It is obvious to point out that by reducing the layer thickness, construction time would increase, so it would be best to selectively use higher resolution methods where applicable i.e. for the smooth interior surface of service pipes. In order to print a building from the ground up, or similar, it would also be essential to utilise different materials.

As different materials harbor different properties it is

necessary to therefore choose the right material and hence the method of printing for producing such a structure.

3.2.1. Materials Used in Rapid Prototyping Construction on site has specific needs, the materials need to be dense enough to not be affected by climatic conditions, but materials in Rapid Prototyping may not specifically need to be so heavy and therefore can be housed in a cabinet as a powder. More often than not materials are spread across a printing platform and then fused together through various methods, depending on the material. Plastics can be either fused using binders or light rays. Binders may solidify the polymer powders using liquid chemicals (glue) to provide the thermal reaction necessary to bond the molecules, and is deemed as a highly cost effective method of prototyping. But whereas lasers which melt a range of plastics including, polycarbonate, ABS and a nylon-silica powder to create a durable and resistant product; light reactive polymers, used during stereolithography, have a distinct disadvantage that the materials have a natural tendency to decompose at an accelerated rate in natural light. Metals can be fused in a similar fashion, by using very powerful lasers, the metallic powders are welded, but some powder layers may not always be distributed evenly which can form voids in the metals, and where there are voids there is an integrated weakness which would not represent a comparable cast piece. But to overcome such a problem parts may be vacuum cast (EBM) to eliminate any air gaps in the material, hence provide a material that is fully dense and suitable for applications such as formula one engine components.

Ross Overfield-Collins

To summarise the following materials can be associated with their respective printing technique:

3.2.2. The Impact Rapid Prototyping Has Had on the Industry Since the introduction of the first 3D printer its popularity has steadily grown. Initially a very expensive process which has now become more accessible than ever with more machines being produced and sold globally. Consequently the cost to buy one of these machines has rapidly decreased; nowadays a rapid prototyping machine is typically valued at ÂŁ6,000 - ÂŁ15,000 (Grenda, Castle Island, 2008), making it an ideal tool for architects to model their ideas physically, giving their client something they can see and touch.

But it also provides a useful insight into the possibilities of making complex

structures (albeit in miniature) in one single print. The finished result can express visually what the architect envisaged. In modern design trends; architects like Zaha Hadid et al. are producing elaborate and complex designs which are easily produced whilst modeling virtually, yet in reality, possess curvatures and visions which are difficult and very expensive to manufacture, unlike their printed models.

3.3. Research Into Printing A Building Aside from the vast resources detailing rapid prototyping and its derivatives, there is very little primary information that examines research into generic construction using rapid prototyping methods. As such many of the secondary sources used were done so with an err on the side of caution, as it is unclear their bias toward one system or another, and because much of the information was gathered from the internet (a source easily tainted), these biases were judged and merited accordingly.

Ross Overfield-Collins

Of those primary sources to note were past papers and doctrines from; The University of Southern California (USC); University of Loughborough (UoL); and, the Royal Melbourne Institute of Technology (RMIT). Although the latter offers only one source of information on research in this field thus far. The other major research group is, in fact, not a group at all, but a private company (Dshape), who have pioneered a different method from the prior three. There were no direct primary sources of information on this particular method, which purported data collection via interviews and emails direct to the founder. The industry has now widely accepted off-site manufacturing, and is seemingly well verse in the subject matter, yet the opposite could be said for Rapid Prototyping and because the nature of this research directly addresses a state-of-the-art process it was necessary to examine a wide spectrum of people. Of those who were contacted it was usually necessary to personally inform prior to obtaining viewpoints on the subject matter. It must be noted that the majority of the information was from past papers and people involved with the research in question. As those people are the most informed, however a small selection of industry officials were also accounted for, as they will be the most likely to use the systems described herein. Due care was taken to ensure that participants were fully aware of the topical nature and that they fully consented to the use of any quotes, information and images that are presented. No waiver was signed however at the beginning of any recorded interview or written statement it was noted that the statements made were voluntary and should cause no harm to their professional status or otherwise. The research already undertaken will be summarised as follows, yet a detailed analysis of Contour Crafting (USC), D-Shape and Freeform Engineering (UoL) Processes will be described in the next chapter. Information from RMIT was unfortunately unobtainable at the time of this research, however their interest in the subject matter must be noted.

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4.1. Case Study: University of Southern California Much of the research undertaken at USC is headed by Dr. Behrokh Khoshnevis at the Center for Rapid Automated Fabrication Technologies (CRAFT). The system (Contour Crafting) is a layered additive fabrication technology, where both off-site and on-site fabrication is maximised, and coordinated in one operation; by extruding concrete, or a similar quick setting paste for the main substructure, whilst placing beams and lintels across areas where spans are required. The primary aim of this research is to print a building in a day, in a single run, with embedded conduits for electrical, plumbing and air-conditioning (Lane, 2004) (See Fig.4.1).

Fig. 4.1 & 4.2: The process & the estimated research schedule of Contour Crafting, including the check/hold points (Image Courtesy of CRAFT).

Ross Overfield-Collins

Their research programme is summarised in figure 4.2; it highlights the check and hold points (AKA milestones) of the research, and shows three key areas which CRAFT deem necessary to build a house in one operation.

These being Materials and

fabrication of said materials; Modular components; robotic assembly; and, the software development that will allow an integration of these past two processes. But moreover will enhance logistics of material delivery and similarly modular delivery. Despite

algorithms

vast

knowledge

and

past

Viterbi

computer

programmes, “much of the software didn’t exist”, says Paul Rosenbloom (USC, 2004) and work was consequently focused on the co-ordination software for multiple nozzles to work in the same operation. This can now be seen with the development of the wall, which was produced with aid from caterpillar funding and engineering expertise, where the biggest success is in regard to a ‘printed’ six-foot tall concrete wall section in one motion. Previously

was

difficult

sustain

continuous extrusion path without material subsidence, but after teaming up with USG Corporation, a quick drying cement was

Fig. 4.3 A partnering initiative between Caterpillar & USC has meant a 6ft wall has been printed using contour crafting, with three nozzles (and two exterior trowels) working in unison. Note the same material is used throughout (Image courtesy of CRAFT).

developed which could be built in 13cm increments with hourly delays to control lateral stability and alleviate buckling. However this rate could be reduced still, depending on the amount of accelerant within the cementuous paste (Khoshnevis, 2006). Each successive layer is extruded and smoothed in 25mm, which is determined from the distance between the bottom of the trowel and the top of the deposited material. This can ultimately be adjusted, however after detailed research from Hongkyu Kwon (2002), it was proven that this was the optimum for the thick and viscous material. He also concluded (without disclosed particulars), that the pressure should be great enough to allow sufficient fusion and plastic flow onto the subservient layer, yet should be low enough to avoid distortion the part.

Ross Overfield-Collins

If the uniform flow was too little, and the orifice was oval and not square in profile, the deposited material would not be squeezed against the side of the trowel and would hence produce a stepped effect, rather than the Fig. 4.4: A Schematic representation of the Contour Crafting process under sub-optimal conditions (Image courtesy of Kwon, 2002).

desired smooth surface finish (Fig. 4.4). This vital doctrine also explained the need for

reinforcement of the material. Innovative solutions were provided by forcing the extrudate through the nozzle with a centralized mandrel, which effectively left a layer with a central void (Fig.4.5).

It was mentioned that this void could be filled with a

secondary material, one which has now become apparent is the nanoparticle metallic pastes (Ishibashi, 2004). Which are of such a high density they could perform the role of rebar within this deposited concrete. Alternatively, CRAFT examined the application of placing reinforcement as coils, on top of the extrudate, which is then covered as successive layers are deposited on top of the former.

Fig. 4.5: Laying hollow sections through Contour Crafting. During, before and after shots of the extrudate throughout the deposition process (Image courtesy of Kwon, 2002).

Amidst the current research, particular applications include low cost housing, emergency housing (for stricken areas), social, and even lunar automated construction. The vision of the research is quite interesting, previous laboratory tests showed promising rates of 200m2 could be built in 24 hours, which far out performs any current construction methods (typically 6 months+ for the same size). In addition it was mentioned that resulting from the shear speed of the construction and moreover the drastic reduction of labour, projections indicate production costs will be around one fifth of conventional construction methods (Mudholker, 2006).

Ross Overfield-Collins

In accordance with the Contour Crafting pick-and-place modular element, German Construction Products giant Degussa, has also partnered with CC to provide their solution to segmentally install components such as plumbing and electrical parts during the layered process (voids are left in the structure to allow placement of the parts). One such solution is the adoption of pre-soldered pipe connections, both to the male and female ends, which are placed and heated in the same operation, by a robotic gripper arm. Other modular elements include standard, stressed beams, yet of note are the electrical and communication wiring, which are similar to industrial bus-bars, but are connected by placing one electrical module on top of another, using robotic automation for that same purpose. These can also be placed in the conduits provided by the programmed blank areas, but where these are not provided, Degussa has suggested implanting sensors that measure the performance of the building. In particular reference to heat sound or stress levels, therefore integrating a smart building system which can be monitored by its occupants, or a system which in the future, may provide the controlling mechanisms for active HVAC and entertainment assemblies.

4.2. Case Study: Freeform Engineering Much of the research from the University of Loughborough has been looking at the application of off-site RP in the construction industry, for near-term commercial deployment. However this has been integrated with more long-term strategies and in particular the automation of wet trades has been given a great deal of attention. Much the same as Contour Crafting (but without the multiple trowels smoothing the surface), However the Freeform Engineering research facility was given a ÂŁ1.2m grant (EPSRC, 2007) to further develop and demonstrate a mega scale additive fabrication method that can print building components, and to develop new processes and materials which will drive the construction industry forward. It has been mentioned that retrofit eco-technologies actually encourages greater embodied energy for the whole structure (Miller, 2008), but FreeForm believe that energy capture can only take place at the design stage, whereby green technology is designed in, or integrated into the fabric of the structure (2009).

Ross Overfield-Collins

This has led to the feasibility study of integrating more functions into less form, this is a similar concept to Contour Crafting, but where CC has yet to develop these ideas further, Loughborough have actively researched the capabilities of printing acoustically designed panels and similarly, panels that minimise thermal conductivity (Fig.4.6). All three of these panels were produced using a Z-Corporation 3-D Printer and gypsum

powder,

which

readily

available source, however one could argue that this chalky mineral is also limited, and consequently is not necessarily sustainable for long-term use. Additionally Buswell et al. (2007) showed that by

extrapolating

the

performance

characteristics of the 3-D printer and the associated material; a hypothetical mega scale printer would be similar in build time to traditional methods (Brick & Block). Although this may now be more in favour of RP with the High Speed Sintering system Fig. 4.6: Panel systems designed by the Freeform Engineering Department maximise the design and prototyping capabilities of RP. Te top image depicts panels which are designed to reduce thermal conductivity, and the images below show a panel (front and back) that reduces acoustic noise (Images courtesy of IMCRC).

which is said to be 10 times faster than previous methods (Hopkinson N. , 2009). Additionally the process may also yield

slightly lower material costs, resulting from the single material construction and reduction in assembly complexity. But, where the distinct benefit arose was in value added operations, much like the afore panelised construction. It was noted that by using the same material, recycling of the building materials would be far easier, plus where there are highly serviced walls, the printed structure would allow for such designs to accommodate these services in addition to a thermally rewarding performance (a lesser k-value than aerated concrete). Yet by examining the acoustic panel Godbold (2007) found that he was in fact restricted in his designs, therefore dissolving the perceived advantage of geometrical freedom. He showed this by demonstrating that Helmholt resonating absorbers use a small orifice

Ross Overfield-Collins

opening out into a void, but this was not possible to reproduce using powder based RP. As the support material, or un-sintered layers would not be accessible for removal. Thus concluding that the process, in this case, restricted the design of such devises. In addition it was demonstrated that there was a vested conflict between the rate at which material was deposited and the resolution required in order to produce clear definition and resolution of the printed structure (Hopkinson N. &., 2006). Although faster printing is economically more rewarding and ensues less shrinkage occurs, it often produces components with poor edge definition. Vice versa, if slower printing takes place, there is an increase in mechanical strength (bonds are more frequent and binding), yet this time it is the accuracy that suffers, resulting from higher material shrinkage, and similarly this is done at a “cost definition”. Nevertheless it is an interesting approach to printing a building.

The part consolidation

associated with this panelised system is much like modular methods, yet unlike modules or even structural panels, these printed panels exhibit greater topological freedom and in use of integrated functions could prove a cost effective method for producing large building components. In Buswell’s paper, Mega Scale Rapid Manufacturing for Construction (2007) he compared rapid manufacture to both traditional and off-site technologies, amidst which he assembled a group of 13 organisations and academia alike, and asked the question; “If you could have a freeform machine today, what would you use it for? The response is summarised in table 4.1.

It highlights six key areas of the building

elements, however one might add into the table foundations as well, as a leveled base to build upon, is naturally a high priority.

Ross Overfield-Collins

From this invaluable insight, it was concluded that the construction industry, in the near future at least, would find RP beneficial where complex forms are requisite to the design and in particular the integration of component and systems integration. latter

point

directly

addresses

This the

combination of panels and its subsequent internal

services,

which

could

the

founding reason why Freeform has led its Fig. 4.7: Multi-service trunking, could incorporate service pipes, with optics and electrical routes, all housed, yet segregated, in the same casing (Images courtesy of I3CON).

research in a different direction from Contour crafting, and has subsequently produced innovations such as multi-service trunking, which has emerged as a distinct viable possibility for future use, but moreover its

production was only realised through rapid manufacture (see fig.4.7). The driver in this case is not a personal vision, as per Dr. Behrokh Khoshnevis, but a conglomerate of the people who may actually use the system. It was also noted that such new technologies could be met with barriers, often deemed as barriers to innovation (Manseau, 2005). Which include areas such as political will, the business efficacy and perhaps more relevant, the ability to conform to building legislation (Soar R. &., 2006). This could be said for global legislation not only national governments, thus a system should be suitably adaptable to all global demands, should it become commercially viable.

Biomimicry However perhaps some of the most interesting research was carried out by Soar, who recently left the faculty, but left in legacy, his ideas of biomimicry and living buildings (Soar R. &., 2008). Much of which was based on his studies of termite mounds, which led to the innovative passive cooling systems in buildings like the Swiss Re, but he demonstrated that by using RP varying thermal masses and thermal resistances are a possibility and cannot be easily replicated through other production methods, this can be achieved topographically, or by altering the materials. Yet in the Adaptable Futures

Ross Overfield-Collins

programme, the initiative fronted by acronym ATKINS, shows that although this is theoretically possible, the potential to mix/grade material boundaries is still unfounded, as it cannot be represented by any CAD system in operation today (Rapid Manufacturing a Low Carbon Footprint, 2008). A similarly conceptual idea was brought about by the same author; Soar stated that house printing machines will be made up of swarms of tiny robots which behave independently, yet work in co-ordination with other robots in a controlled building regime, seen in his study of termites. He realises, “this is the rest of my life’s work, and possibly my children’s as well” (Pimlott, 2009), but this idea has been backed up by several bloggers on the contour crafting

website

(Contour

Crafting

Blogspot,

2006).

One

mention

Civilisation_in_2100?, who states in the same vein, that small robots could crawl around a skeleton structure i.e. a wired frame, and ‘work 24/7’ at a relatively leisurely pace, conversely communicating to a centralised computer, which ultimately results in greater construction yield, from little energy expenditure. This is similarly a scope, which ATKINS feels necessary to research, as part of their £2.9m grant is dedicated for Automated biometric design integration, where novel software algorithms will permit the automated design of several geometrical elements. But where this research looks toward the near-future, it encompasses software development of waste minimisation during the construction phase. This includes tooling paths that can optimise the latter; digital supply chains; and the reduction of greenhouse gas emissions over the whole product life-cycle. Hague, a professor at the university stated, “The benefits of the technology for consumers, industry and the environment is quite staggering. For example, a 50 per cent weight saving in components will mean much less material/energy is needed, which means less CO2 is released into the atmosphere. Additionally, a reduction in wastage at the manufacturing stage and the ability to create parts where and when they are needed, rather than at a factory hundreds of miles away, will also help reduce costs and the environmental impact.” As such, by engineering the components correctly, gains could be made in regard to sustainability, a hotly pursued governmental agenda, and components which are “super light, super strong and functional” may become a reality (IMCRC, 2009).

Ross Overfield-Collins

4.3. Case Study: D-Shape After initial talks with Enrico Dini, it became clear of his intentions to print a complete structure using his technique.

Where the economic downturn has affected Contour

Craftingâ&#x20AC;&#x2122;s research and development budget (Pimlott, 2009), D-shape is a privately funded operation and consequently is only limited by the budget of Monolite Ltd. Further still this has enabled D-Shape to follow through with its ambitions, to be the first of the three methods to print a self-supported structure, the Radiolaria. Moreover alongside Architect James Gardiner, of Faan Studio, construction of the first printed house, the Villa Rocce House (fig. 4.8) in Porto Redondo, Sardinia has already started and is due to be completed late 2010.

Fig. 4.8: Conceptual drawings, Working Details and the printed elements of Villa Rocce (Images courtesy of Enrico Dini and Faan Ltd.).

The system is much like methods shown in 3DP, or 3D Printing, and uses similar algorithms from the 3D printing processes to manipulate 300 nozzles, emitting the binder onto the substrate. Magnesium oxide powder (the catalyst) is dispersed amongst the grains of sand, which is deposited and smoothed in 5-10mm thick layers. This catalyst is then activated as the rig passes over the sand bed and selectively drops a chloride binding liquid to form a viscous set (value between 1x10~3 Nsm-1 and Fig. 4.9: Inorganic binder being deposited over the print-bed. Note the size of the stream and the bead which results from the process (Images courtesy of Enrico Dini and Faan Ltd.).

2x10'3 Nsm-1 (Dini, WO/2009/037550, 2009)) at the point of contact (fig.4.9).

Preliminary tests used a premixed binder, which he then found to be troublesome as the 1mm aperture of the nozzles quickly became blocked.

In order to alleviate this he

premixed the binder with the sand, as previously mentioned.

The machine now

Ross Overfield-Collins

re-circulates the binder when the printer is not in operation, as this eliminates any stagnation or desalinisation of the solution. After the rig has made the necessary number of sweeps across the printing deck, the unbound granular material is removed, revealing the printed structure. Of which has a 25dpi resolution over a 6x6m printing area, up to 3m in height. However this height is rarely necessary, as the most efficient use of the printer (and material) is to fill the whole area of the printer deck with low-rise segmented pieces, which optimises the use of the machine, but ultimately speeds the process up, and conversely these segments can later be glued together using the same binder and catalyst (Dini, Interview 11/12/09, 2009).

It may be easier in the long run to print an entire building, or full height

components, but this will not maximise the use of the machine, nevertheless architects and engineers still desire a machine that will build the structural entirety, as Xavier Dekeste of Foster and Partners states, “the idea is to press print and just do it”, therefore simplifying their role as a contractual supervisor and enabling them to concentrate on their primary function, design. On the other hand, one major advantage of this method is the ability to produce synthetic marble-like stone, not over a period of decades, but hours. It takes one day to print 150mm of stone (with operation maximised at 300mm) for a 24hr period, and comparing this to the other methods shown in this paper, this is by far the slowest and most privative process. During a one-to-one interview, Enrico Dini was quite open to admit the process is relatively slow, partly factorial of the human recalibration upon every layer, he states quite jovially, “there is a certain dumbness to the binary logic”, but it’s also the most sustainable method out of the three. Its inorganic compound does not contain any hydrocarbons, but additionally the sand, which is the dominant material in the granular mix, is widely available globally. And, due to the microcrystalline structure, it possess mineral-like qualities, which during testing have shown significant hardness and high tensile strengths over and above that of concrete (the primary material of CC and Freeform).

Ross Overfield-Collins

Yet the process itself limits the potential of this method. It could be seen in fig. 4.9 that the streams ejected from the nozzles were of a large diameter, which will unquestionably affect the final resolution. Although 25dpi was stated, the printed parts require extensive work, removing the unbound mixture, beating off the recalcitrant parts (Abrahams, 2010), Fig. 4.10: A Hypodermic needle, illustrating the formation of a large droplet size from a small aperture (Image courtesy of WhiteNeedles.co.uk).

and then sanding the exterior. This post processing seems illogical when the objective of RP is to

deliver a working product as soon as it is printed; however because of the scale of the operation these limitations are exaggerated. One such limitation that contributes to this problem is due to the excessive ejection of the binder from the on-off calibration, and similarly the nozzle heads are only 1mm in diameter, yet they eject a 5mm wide stream as a result of the surface tension from the solution at the tip of the nozzle. This is easily demonstrated by examining a hypodermic needle when little pressure is applied to the plunger, small droplets appear far greater than the head of the syringe itself (fig. 4.10). Moreover Prof. Mark Burry stated that when the drops form as a solid, the binder naturally spreads linearly when it comes into contact with the compound (SmartGeometry Day 2: Public Symposium and Reception , 2010), and when the roller flattens the successive layer, which is designed to increase the density of the material, further compresses the previous layers which exaggerates the previous inaccuracies; consequentially a designed 5mm bead is compressed to an approximate diameter of 10mm.

This is well documented and during our interview

Enrico Dini (2009) mentioned that as a result of this process, an object, i.e. a pipe with a designed internal diameter of 80mm could end up with an internal diameter of no greater than 50mm. This can be compensated during the design stages, however using modern methods of construction as a precedent, in particular modular units, construction operatives and designers often prefer precise methods (Corus, 2007), and were primarily attracted to RP in the first instance because these processes offer a greater design freedom, with the capability to produce accurate buildings (Schumacher, 2004) and ease of part integration.

Ross Overfield-Collins

Yet designing, ordering and retrofitting of windows and doors is still a necessity with this approach, as the method is thus far, incapable of producing a building with a high enough resolution to incorporate other elements, per Freeform. However it can be seen from fig. 4.8 that conduits can be printed (Dini, Interview 11/12/09, 2009) as part of the structure, so by optimising the structural element, internal geometry has proven to reduce the materials whilst effectively improving the strength through load distribution. And, beneficially, this house has also shown that hidden services could be integrated during the physical erection of the components on-site (Gardiner, 2010).

4.3.1.Interview with Enrico Dini During the interview with Enrico Dini, it was put to him that this method is not necessarily the most accurate system with regard to edge definition etc. He continued to mention that he is the solitary financier of this project, but interestingly he has looked into lunar construction with this method, much the same as Contour Crafting, but where CC has been given research grants from NASA, Enrico Dini has collaborated with the European Space Agency, and in particular the Aurora Programme, which has led to a research contract between these partners, plus the likes of Lord Foster (Foster and Partners) to provide the design. The main issue to improve the system is funding of governmental proportions. Bearing in mind this is a two-man project up until now, Enrico claims it would take close to 20 staff for materials development, 20 staff for chemicals, 40 staff working on the machine and a further 20 developing the software, totaling an approximate 100 extra staff required to make this system commercially viable for the mass market.

However

learning and development could be made through lots of smaller, independent parties, and this seems to be the direction Enrico is heading, as part of the Architectural Associations remit is to install a version of his machine in the Metropolitan University, London.

They themselves will be able to concentrate academic studies on the

apparatus, and will be able to offer new solutions and processes to the technology, much the same as Contour Crafting, and Freeform, with their associate research establishments. In the near future Enrico believes his system will be marketed toward outdoor furniture, bathroom modules and curved cladding, all of which have been demonstrated by

Ross Overfield-Collins

D-Shape already. But the system is still costly; nearly £2000/tonne including operating and development costs, yet in the future one would hope this becomes more competitive and nears the quoted £750/t. Much of which is labour costs as the materials alone are £175/t, so if the system becomes more accurate, there will be an associated saving in the amount of after work that is necessary for a commercial product. Enrico is well aware of this and mentions D-Shape “cannot match the cost of off-site construction right now but they [Modern Methods of Construction] cannot produce freeform structures like D-Shape”. Enrico has been working on this technology since 2004, Freeform before 2006 and Contour Crafting prior to 2001. Earlier research was carried out by Joseph Pegna in 1997, which demonstrated a similar use of blanketing sand deposition and selective application of binder, per D-Shape, and perhaps could be accredited with the notion that RP technologies could be used in the construction industry.

He highlighted the

importance of building scale, in his research he calculated that to fully scale up existing Fused Deposition technologies, individual beads of material would be 10mm in circumference, not flat like D-Shape, he further concluded that whatever process is developed must be able to deposit materials at construction rates (Pegna, 2007) and the idea was developed still, where the latter must be a pre-requisite in addition to the resolution of the smallest designed element, for functionality purposes (Soar R. , 2006). These are the desired characteristics of a viable mega scale RP processes, but where all three methods falter, is the combination of both these elements in the same operation. Despite the need to use multiple materials, the primary operations are still to be developed to their operating potential. Here lies the crux, where is this technology heading?

mega scale Rapid Prototyping the future of

Ross Overfield-Collins

5. Discussion 5.1. Drivers for change It is being promoted by the Housing Forum that product availability will accelerate when house designs are tailored to the requirements of manufacturing processes (Homing in on Excellence, 2002). But why should this be so where, after all the clients themselves are reportedly asking for more bespoke designs. According to Gibb (2003) and with comparisons to off-site manufacture, the client is also keen to improve; the construction and procurement time; quality of the finished product; total cost to the client, and, productivity issues, in that order. Yet using off-site manufacture the design freedom is somewhat hindered by the preengineered nature of the modules or components, often box-like, inorganic structures. In the past architects have been accused of not thinking about how products are going to be made, and this is true of many concept designs which are increasingly being abandoned because of cost. Professor Behrokh Khoshnevis found his own 30m x 10m housing project scrapped because of the economic downturn (Pimlott, 2009). But where investment can provide this step-change is with the intervention of government legislation and funding of an equally grand scale. Zero Carbon homes has definitely shown a change in the regulatory frameworks, which could be a major factor for the investment in off-site production, yet this issue of sustainability is a barrier that mega scale RP has to overcome. Vice versa, RP is not the resultant of sustainable development; it is merely the means through which it may be delivered.

5.2. Sustainability For 20,000 years building has needed intense manual labour, so why is the industry still facing problems such as low productivity, poor quality, low safety and a skilled labour shortage? It is widely known that skilled labour in the UK is in short supply, which could partly be the reason why the associated quality is one of the key drivers for the adoption of new construction methods.

Ross Overfield-Collins

By using automated construction, especially ‘Rapid Prototyping’ on site, construction processes will ultimately entail further loss of unskilled labour in the industry, or, the ability to not need to employ as many people on site. Mega Scale RP may however provide more employment in the software development and hardware production sectors, and it will invariably require operators to be qualified and/or trained to run the software i.e. software engineers with a background in construction. So in regard to the sustainability of personnel, by using mega scale RP employment will in fact decrease on-site. And this itself raises issues of low-skilled jobs available to the economy, one which the government will look upon unfavorably as this is the sector most closely linked with unemployment (Pierrard, 2003). But where there are reduced personnel, there is an inevitable reduction of injuries on site. It is true that engineer’s build in safety factors (which may involve over-engineering components) and I would stress at this point that this increases costs of materials. Yet the issue is not added material in view of safety, it is the waste and amount of materials being used.

Environmentally concerned corporations continually address this idiom,

however it is the time it takes to construct the buildings that has a large affect on the profitability of a project. Rt Hon Nick Raynsford stated after a government led MMC initiative, that “an average of 13% of man hours on a project is wasted on non-value activities” (McKeown, 2009), if this is reduced even by as much as half the savings would be drastic. Further to the above, RP systems use immense amounts of energy and consequently running costs are at a premium (Grimm T. , 2002). Similarly a mega scale operation would also use a discernable amount of said energy to power the automation, let alone the high powered computer required to calculate printing paths.

But

emerging

technologies

‘Free

Electricity’ can utilise the physical properties of

Fig. 5.1: The Hummingbird/Sundance electrical generator, by Innovative Technologies Ltd.

magnetic repulsion to rotate an electrical generator. This simple yet effective system could be incorporated into the design and provide a truly sustainable machine. It would therefore be the role of the materials technologist to provide the most ecological raw product to further enhance the sustainable credentials of the system.

Ross Overfield-Collins

5.3. Investment 5.3.1. Investment in the Construction Industry Currently, in order to meet sophisticated clients needs, modular construction is being used with common regularity, whereas previously ‘tried and tested’ methods were the only course of action; however, modern trends seem to favour off-site production (Pan, 2005), whereby a bespoke production line (often robotically controlled systems) will deliver a modular, ‘flat-pack’ assembly ready for fast on-site erection. André Manseau’s book, Building Tomorrow (2005), shows the majority of innovations in the construction industry are generally incremental and quantative data on innovation in the construction industry is rare. Traditionally the construction industry is what some may say impotent to change, even though it is generally agreed that there is a need for more innovation. It is exacerbated by poor research and development efforts, just 0.3% of turnover, compared to a staggering 10% of the pharmaceuticals industry, and the majority of which originates from the supplier of the materials i.e. the use of CNC in the steel industry, not the methods of construction, or the application of the materials (Eurostat, 2000). Most importantly of all is that the public and construction industry know very little about Rapid Prototyping. The more the technology is used in architectural firms and the more mega scale rapid manufacture is publicised, the lesser the animosity will be towards the method and a greater chance for such technologies to be taken up by large construction companies.

5.3.2. Investment in Mega Scale RP The construction industry relies heavily on other industries to deliver new technologies, and new products within the construction industry are not likely to appear without high capital investment. Innovation can be costly, as all three case studies have shown their dependence on research grants, so when there is so much interest in the systems from large reputable companies, why do they not invest? Commissioner for CABE, John Miles identified that “the parties who need convincing are those being asked to risk their capital in transforming house building into a manufacturing industry” (Abley, 2002). Speaking out at the Homing in on Excellence

Ross Overfield-Collins

Conference, he continues that because of the secretive nature of R&D “it will continue to be difficult to recoup initial investment in the current climate”. The case studies have shown that printing a building in full or in component form is a long way from being fully developed.

Although additional research has been undertaken in

material properties, engineering of the components and reducing wastage etc., the issue is delivering this on a scale suitable for construction. This research, much like the investment from Enrico Dini was in the private sector, and it should be put to the reader that the major driver for evolution is therefore governmental investments and incentives. As minor investments incur naturally slow/small step changes, which although they develop the process, the method takes and has been shown to take decades to materialize as a common user product (Sedean, 1996).

5.4. Software One of these minor step changes, which could have a big impact on providing a more integrated client input to the design, is the use of so called black box software.

This

seemingly invisible software can interact and modify the design to new calculated in addition to engineered parameters of the structure, which could improve the client’s satisfaction. But moreover in conjunction with mega scale RP, could offer self-build clients and any layman for that matter, an opportunity to provide a structurally sound and individualised building (Peters, 2010).

5.5. Designing the Future The large benefit of using mega scale RP is its ability to realise almost any design conceived, even for the most ambitious of architects as long as it is engineered properly it should be buildable. The only limitations of this technology in the future is the designers own ambition.

…………………………

Lindsay Lucas: Technical Project Manager at Kingston Communications

By using mega scale RP nearly all architectural styles could be catered for, unlike other methods of construction, yet similarly with most current building methods there are always limitations to the design, whether it is material limitations or the buildability of the design. Construction managers continually favour designs that are easy to construct, if the machines are capable of printing the building in one operation, the machine would do this for them, and hence items like jointing details need not be an issue.

Ross Overfield-Collins

Another point to raise is the affordability of the design. Off-site construction is generally used in conjunction with associated economies of scale, or mass production.

The

advantage of this is the product can be continually improved as the design team becomes familiar with the system and can use any after sales knowledge to better the cycles of manufacturing and design (Abley, 2002). But whereas modern methods of construction may not be able to provide economic low-volume production, the mechanism for virtual prototyping and physical printing of a one-off building, could increase the design flexibility, productivity (Hopkinson N. &., 2006) and hence introduce a mechanism for economies of small-scale production. The majority of current off-site manufacture can only produce buildings and components consisting of flat panels, however what happens if you wish to manufacture more organic structures. You could make it from numerous flat sections arranged in a way that creates curves. But architects today are increasingly moving away from the box shapes and looking into more fluid forms like Eda Yetisâ&#x20AC;&#x2122; Hurricane House (fig. 5.2). These types of structures are self-supporting using

SLS),

(modeled offer

vast

spaces within, and are very complex in their make-up. This sort of design could be incorporated

into

Mega

Scale RP, as it is possible to do it on a macro scale already, illustrated in fig. 5.2. Fig. 5.2: Eda Yetisâ&#x20AC;&#x2122; Hurricane House Prototype, produced by Selective Laser Sintering, highlighting the structural use, and the possibility of engineered buildings (Photo Taken at the Architectural Association Stand EcoBuild 2009)

If the same material where to be used for the up-scaled

operation it should be feasible to assume that the building could withstand the same scalar structural forces as per the macro version. In view of EcoBuild 2009, No method of construction so far can offer fast production of this form of construction and that is possibly why it is not a reality yet. But architects are used to using and adopting 3D modeling, whereas construction operatives are only just realising the

potential of this software and are warming to the use of systems like BIM (Madsen, 2008).

Ross Overfield-Collins

5.5.1. Archineering “The new language (or style) of architecture seems to be based upon the adoption of a new generation of 3D modeling tools” (Schumacher, 2004), Zaha Hadid’s partner, Patrik Schumacher goes on to mention how the use of CAD was keenly taken up to support the ambitious ideas of the designer as it allowed new levels of structural complexity, fluidity and plastic articulation previously very difficult to draw and engineer. With today’s knowledge virtually anything can be built, but if some elaborate structure is preferred the client must be willing to bear the detrimental aspects of his/her aspirations, namely the programme, quality, cost and possibly safety (Corus, 2007).

And with

current practice architects often have to be restrained from creating something too oblique otherwise engineering the structure cost-effectively would be near impossible, as a result designers must only design that which can be built using existing methods. If architects intend to use mega scale rapid prototyping as a construction method there is little reason why they cannot produce elaborate buildings.

However the primary

designer’s role may change to include greater engineering capabilities, resulting from the lack of intermediacy between design and construction.

Consequently for the

purpose of this paper these design personnel will be coined Archineers, and because there is no possibility of post design changes once the print is under way; the designed building must therefore be ready to build upon completion of the design. So due to the irreversible nature of the construction method, design must be absolute and final upon handover to the construction team.

5.6. Materials, Methods and Integration Increased responsibility at the design stages also encompasses greater opportunities to maximise efficient innovative space solutions, yet by examining the case studies it was clear to see the potential of this is still yet to be fully realised.

5.6.1. Integrating two Materials In essence there are three major materials used in construction, dense/load bearing, plastics and metals. It was shown that producing a smooth transition between different materials is near impossible with current methods, yet if the material were to be premixed, per D-Shape, with three troughs of (a) Material A; (b) 50% Material A – 50% Material B; and (c) purely Material B. These materials could be deposited in sequence

Ross Overfield-Collins

where the integration occurs, but in addition the CAD model would not necessarily need to define the different printing characteristics as the mechanisation and operation is the same. These may be retrospectively coloured separately in the modeling stages, but the automation software for the binding agent need not recognise the significance of the separate material. Therefore this issue could be technological rather than a software issue, which is defined by Hopkinson et al. (2006) as being one of the major barriers for dual material grading. However where Hopkinson has not conceded that to achieve optimised components like those designed by Loughborough (fig. 5.3), the process may need to involve deposition methods i.e. FDM, rather than the previously tested Laser Sintering.

Fig. 5.3: Typical cross section of a wall (A) and a comparison of an impressionistic view (B) of the capabilities using mega scale RP (image courtesy of Loughborough University)

The major advantage of using a deposition method over powder blanketing operations is the ability to create voids without any un-sintered powder filling said voids. There are two

emerging technologies that look the more likely to provide this technique, namely HighViscosity Jetting and Fused Deposition (fig. 5.4).

The latter offers a powder-based process, but unlike other powder systems, this jets the material into a melt pool, and where paste systems may

find

integrating

materials

difficult this system could find the difficult, Fig. 5.4: Fused deposition systems. This particular example is a Fused Metal Deposition. Note the air stream and melt pool (images courtesy of Trumpf and Hopkinson, 2006)

mixing of compounds and grading between the two a simpler operation.

Ross Overfield-Collins

5.6.2. The Operating Mechanisms There is a possibility of moving printer heads not only in the x,y,z axes, but in the elevation plane, printing cantilevers, beams and arches could thence be possible without the necessity of formwork, so long as the materials have sufficient stiffness and a good mechanical bond to overcome the effects of gravity. By making use of 5/7 axis robotic arms these elements could be easily produced as the arm can manoeuvre in several planes at once. Yet the limitation is that there would be far fewer printer heads when using this system, hence slowing the construction process. Unless either several of these were used at once (expensive), or only one was employed to produce just these elements alone, and a standard 3-axis rig to produce the rest of the building. The likelihood of integrating both a rig and robotic arm at once is very slim at present as the two systems are both complex in their own right, but combining the two would involve years of research and development, that would probably come after either one type is commonplace on the market. Enrico Dini estimated this to include 100 extra employees. Consequently automation should be kept as simple as possible, and the best solution at present would be the 3-axis rig, which all three of the mega scale rapid manufacture research groups are using.

Fig. 5.5: Multi-axis Robotic arm using Contour Crafting techniques. It shows that Contour Crafting has considered using a robotic arm, but developing such a system in the first instance would be very expensive, hence alternatives have been sought. (Image courtesy of CRAFT).

Robotic arms would favour the paste layering systems of Freeform and Contour Crafting and high viscosity jetting, but as ecologist Colin Baker states, â&#x20AC;&#x153;the most prosaic things in automation are the things that may trip you upâ&#x20AC;? and robotic arms are no exception (Baker, 2009).

The previous and most prolific use of robotic arms is in the car

manufacturing industry, however they are not necessarily free-moving machines. Once the robot is placed in a position where it may weld or do otherwise; it learns this and then returns to its original resting position.

The movements are all therefore pre-

planned, and thus the associated computer coding cannot be used for different movements, necessitating the development of new movement algorithms (Dini, 2009).

Ross Overfield-Collins

It has been suggested that a gantry system like all three methods was expensive and wasteful in resources, and could be construed as slow to erect unlike a hexapod system (Lipkowitz, 2006). RoboCrane is one such area Contour Crafting is looking into, and operates in a similar fashion to cable operated cameras as seen in many stadiums around the world.

But the future use externally, may be an issue as the crane is

suspended on wires that have proven unreliable in terms of stability where winds increase the tension in the cables, consequently an inaccuracy occurs at the foci of the camera. This is compensated by extra stabalising equipment, however this may not be possible with a printer nozzle as the stabalising equipment cannot eradicate all jerky movements so inaccuracies will inevitably occur.

On screen this is alleviated by

switching to a different camera perspective however when printing a building the equipment would need to be 100% reliable, with little or no flaws in the accuracy of the automated movement. A more suitable application would be to use hydraulic arms (fig. 5.6) or roller screws, which would extend and contract the arms according to the position required for material deposition. However it can be seen that this rig would be just as complicated and expensive as the gantry approaches to manufacturing.

Fig. 5.6: Hexapod System by NIST. A surprisingly accurate CNC system which can tilt the head of the mechanical head, albeit to a limited degree, however it offers a versatility far greater than standard gantry sytems (Image courtesy of National Institute of Standards and Technology, USA).

Ross Overfield-Collins

5.7. Acting on the Drivers for Change Some people whom were interviewed did offer some animosity toward the idea of printed structures. It must be said that robotics in construction was heavily researched by the Japanese during the 1990’s, to varying degrees of success. It was with this in mind that Nick Nisbet, of AE3C, speaking at EcoBuild (2009), mentioned that “there is not a lot of enthusiasm about robotics on site...this area is nothing new and was seen as a gracious failure by the media in Japan”. His and many other personnel in the industry are looking toward the use of robotics in factory conditions. He similarly mentioned that it would be detrimental to leave an expensive machine out in harsh conditions where another system under cover could produce the same building in better working conditions, without the problems associated with high winds, driving rain etc. However interestingly, he did note that if the system could do away with scaffolding completely this would be a “big gain”, but would only become prevalent if value supports the use of this system.

5.7.1. Quality-Cost Correlation Automation of off-site manufacturing has improved upon both quality and the cost implications; some may even go far as to say it has now become the standard to model all other processes against (Baker, 2009). This is most relevant in the production of steel structures, where the manufacturing processes’ are often computer numeric controlled (CNC), and hence offer a controlling mechanism for factory tolerances.

The graph

below however shows the relationship between achieving this greater accuracy and cost. It shows that the lesser the

tolerances,

the

greater the cost of site production through extra work. D-Shape is also is suffering from this, but surely

if all, or most

elements are produced using

the

same

Fig. 5.7: The influence of dimensional accuracy on steel structures v. cost calculation (image courtesy of Urbanska-Gaewska, 2008)

technique, supply-demand curves would suggest, the more times you use a system (like robotics, which can achieve high accuracy), the running cost will reduce. So it may be

Ross Overfield-Collins

the opinion that if high tolerances are required, and they invariably are, robotics is the best method of producing such results, cost-effectively. It is unfortunate that all three case studies shown are still currently very expensive processes. It is true that material costs are still high, but what the massive research investments toward Loughborough University (ÂŁ3.8m+) have shown that this process is still being explored in regard to its niche, let alone its development.

As part of Loughboroughâ&#x20AC;&#x2122;s

Freeform exploratory study they simulated a scaled version of a machine

Z-Corporation

this showed

itself to

beneficial than traditional wall construction techniques in terms of cost and speed and is

Fig. 5.8: Freeform wall construction cost comparison (Image courtesy of Buswell, R.A. et al., 2007).

illustrated by fig. 5.9 & 5.10 consecutively.

5.7.2. Speed Rapid

manufacture

not

necessarily

concerned with hastening the manufacture process.

The name is actually a misnomer

conceived for marketing purposes, but the elimination of any tooling does in fact reduce the time to manufacture a prototype object, much like a one-off building.

However figure

5.10 emphasises that this is only of a large benefit

where

very

detailed

sections

are

Fig. 5.9: Comparison of Freeform Construction v. traditional construction: time to completion of a wall section (Image courtesy of Buswell, R.A. et al., 2007).

produced. And it must be noted that traditional large walls are not necessarily high detail items, thus speed may therefore be unaffected by the elimination of tooling for these components. If a wall or building element were to be of enhanced detail i.e. insulation and wall thicknesses were changed in relation to required performances, or the wall was an organic form; rapid manufacture techniques may then prove beneficial for the project delivery time.

Ross Overfield-Collins

The reduction in construction time is possibly one of the most attractive aspects to a contractor. And when comparing the speed of the mega scale RP process’, Contour Crafting outshines its competitors for the rate at which a structure could be built, where more representative methods of RP i.e. D-Shape and FreeForm, suffer from slower build speeds. RP is largely constrained by the printing area, and much the same could be said about the printing area of the latter two, but where Contour Crafting is largely unrestrained in terms of printing area, its speed and deposition thus far does not deliver an air tight structure. Consequently any sustainable credentials in regard to energy usage and daily performance cannot compete against existing building techniques (Kwon, 2002).

5.7.3. Quality The same process has exhibited some development problems in terms of the binary onoff nature of the extrusion path. D-shape shows a similar lag time between the software and the shut-off valve of the liquid, consequently both systems work best in continuous printing motions, however where this will become a distinct disadvantage for the integrity of the structure, is the edge detail of the components. Once again for CC, the trowels, which smooth the outer edges of the concrete, do offer a solution to the external and internal surfaces.

However where the nozzles are

required stop and start, before and after an opening, like a doorway or a window, the surfaces adjacent to these components will be unfinished, and one would assume that in modern methods of construction these elements are very weather/air-tight. Yet the processes shown by D-shape and CC offer neither of these qualities. Much the different could be said for FreeForm’s approach, as the research institute is focusing on using existing RP techniques such as deposition and even new approaches like high viscosity jetting. Which have shown on a macro level to offer the high levels of edge definition and resolution that is required for integrating modern active and passive systems, like air thermo-siphoning (stack effect) trunking, HVAC and light tubes etc.

5.7.4. Design Freedom From an engineers perspective Jalal El-Ali, of Buro Happold said the “main interest is making structures more efficient by controlling the amount and distribution of material in the structure according to its needs” (2007). He continues “we have the knowledge to design such buildings, we just need the tool”.

Ross Overfield-Collins

The major advantage for rapid prototyping, yet the major disadvantage of Contour Crafting is the degree of architectural freedom. CRAFT have shown themselves capable of producing walls, however these are largely only in the vertical or near vertical; the exception to this is the ability to produce domed sections.

However this seemingly

archaen approach may not suit the architects who are actively following, and have a vested interest in the project, like Xavier Dekeste of Foster and Partners, and similarly Gehry Technologies (Pimlott, 2009).

As Dr. Khoshnevis stated, “Architects are the

strongest advocates of this technology” (Mudholker, 2006), so a process, which does not restrict/limit their design intuition should be a priority for mega scale rapid manufacture. It was shown that the less radical approaches to mega scale RP i.e. Loughborough Universities Freeform and D-shape, demonstrated that architectural styles and highly engineered components could be catered for, thus geometrical optimisation was a distinct possibility and similarly the use of material is easily reduced, hence providing a more sustainable part. In the case of D-shape this has been proven with structurally engineered stone and a structure has been built which most likely couldn’t have been produced by any other means without huge expense. It is because of this skin and core strategy, akin to many RP processes, those new selfsupporting geometrical forms like Eda Yetis’ Hurricane House could become commonplace in our society, but the technology can also accommodate more classical avant-garde Gaudi designs without a major team of stonemasons. It could even provide a viable option for restoration projects, where plaster roses are difficult to replicate and damaged gargoyles on the extremities of religious buildings are equally challenging and time consuming to reproduce. For this reason Mega Scale has a future application in the industry. In collaboration with black box software it also has the potential to provide clients with the tool to build previously unthinkable designs. Moreover by exploiting operational parameters and characteristics, automated construction can provide integration and increased functionality above and beyond existing construction capabilities. Further still RP is proving itself to be one of the drivers for material diversity, like compressive (spongy) structures, gels, fabrics and solids, although much of this is impractical on a mega scale due to the time consuming nature of micro fabrication. Nevertheless it does highlight the range of possibilities that Mega Scale operations could be providing to the industry in the coming future.

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5.8. The Future of Mega Scale RP in construction The ultimate goal for Mega Scale construction was highlighted earlier as a process that must be able to deposit materials at construction rates, but also one that incorporates the resolution of the smallest designed element. In ideal circumstances a perfected system would utilise the speed of Contour Crafting paste layering system for the main structure, but for pipes, services and cantilever sections, Fused Deposition or High-Viscosity Jetting is favoured as it can offer good quality â&#x20AC;&#x2DC;tightâ&#x20AC;&#x2122; structures. In reflection both systems would preferably act in unison, and this would ultimately require the Fused Deposition or Jetting to speed up, or vice versa, the paste layering should slow down. Seen, as the latter is more the likely it would be deemed that the speed of a multi-material process would be inhibited by the same method that could provide the detailed elements necessary for a fully functioning building upon completion of the printing action. It should be noted that in order to produce structures that offer true spatial and topological optimisation, powder-blanketing operations are likely to hinder the design process rather than benefit it. Aerated structures or honeycomb structures which in construction have proven themselves to be very light yet strong functional arrangements, may only be possible through material additive processes. Consequently particular research and investment ought to be forwarded into the speed of these processes, should this state-of-the-art construction method become a feature in modern day construction. Climatic variation could be accommodated by the use of off-site construction and unlike current off-site methods, curved panels with different wall thicknesses could be produced. Likewise off-site manufacturing could also provide a better quality product as a result of these factory tolerances that may otherwise be affected by external factors. This purports the necessity to manufacture components or sections of the building as no feasible transport system could deliver a complete building economically. But to fully maximise the logistical implications, these panels should also be in accordance with standardised lorry widths and lengths (Royal Haulage Association suggests 3m x 12m as a typical value).

Ross Overfield-Collins

Energy shortages may also be accommodated in the design, but also off-site processes could utilise technologies like Free Electricity, as illustrated in this paper. Skills shortages would be dealt with, as the automated nature of the process will use fewer workers in total, but more skilled labour. Which is a tough political prospect, whether this could be construed as a positive, is possibly yet another area for research, but one which could provide an insight into the extent of the barriers to innovation. One area where this process will benefit all is the reduction of waste. The system uses less material as a result of its design characteristics, but on a similar subject could integrate immerging underground waste management technologies, like that of EnVac (see appendix), into the actual structure, or even individual rooms if necessary. Tension structures may also only be possible with the correct support for the extrudate or similar to be printed upon. Rapid prototyping machines have previously been able to produce cantilevers and spans by using water-soluble printed formwork. This may be useful for producing doorways and such like, but like smaller machines, it will require a lot of messy after-work to the structure. But it has been proven time again by D-Shape that after work increases the final cost, thus this is another area for consideration of future research. Further areas to note are: 1. Integration of Two Platforms, where robotic arms much like a human arm can access very tight spaces, and a more traditional gantry rig collaborate. 2. Integration of Two Materials on a Mega Scale, and; 3. Non-Cartesian Robotics (free thinking nano-bots)

Ross Overfield-Collins

6. Conclusion: the Direction This Technology is Heading Although this process has the potential to deliver on so many drivers for change, the fact of the matter is, it will not be able to do so in the near future unless the correct funding and research is applied to these technologies. However it would appear that there are two different directions which mega scale rapid prototyping is heading toward. Firstly the process of Contour Crafting uses the extrusion process to build the envelope, whilst using several robotic applications to deliver the modular floors, services et al. in a specific manner that will allow the extrusion process to be a continuous operation until the entire structure of the building is completed. Secondly, both D-shape and FreeForm offer more conventional modular delivery systems. Either by having an on-site factory based system or an off-site production plant, as seen in many modern methods of construction. Loughboroughâ&#x20AC;&#x2122;s own research has examined the two of these options and concluded the use of off-site manufacturing was more attractive to clients because of the space advantages it gives the clients and contractors at their particular site, and it should be this method, which also uses common user plant, logistics etc. that is recommended for use with mega scale RP construction. This paper agrees with the above statement, as this has the added advantage to get rid of any superfluous protection against the elements. Contour Crafting would most likely need an exterior cover to allow operations to work in conjunction with adverse weather, however where components are built in factory conditions, construction could remain unharmed and untainted by what is happening externally. Moreover where the use of powder systems are necessary, for instance Fused Metal Deposition; this powder and the inert gasses required to build the material in the melt pool will not be affected, thus the quality of the final product should remain high. Obviously if this could be replicated on site it would provide enormous benefits in material supply, logistics, and continuity of the building fabric. But one must note by building an envelope of such grandeur prior to construction, this defeats the object of printing a building in the first instance. Referring to the title of this paper, it could be said that this process is not in fact an evolution as such, but a development of existing ideas. It was shown by academics at Loughborough University that in the near future the system is likely to be used in a similar fashion and even

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in competition with off-site manufacturing.

The key advantage in this respect, is the

geometrical benefits that modular units cannot address, as these are largely pre-engineered units, which principally become cost effective due to the limited structural design required at the procurement stages. Because of ‘black box’ software, mega scale RP can offer the same level of procurement savings, but where off-site construction reduces the supply-chains, mega scale RP would reduce this further to only a few major material suppliers. So by manufacturing the building using RP the current off-site manufacturing methods could quickly become outdated and could offer an easy transition for construction managers and clients alike. The similarity of the management structure to off-site construction would prove beneficial for those in the industry who may prove impassive to change, but moreover would allow other mechanisms like logistical transportation, and even site plant to easily adapt to the new structures that could be delivered. It is true that the aim of contour crafting is to build/print a structure in its entirety and this may be of great benefit if geometrical limitations are addressed, but out of the three methods examined, it is the only one which is carving its own niche, whereas both D-shape and Freeform offer solutions as site factories or off-site construction plants. Contour crafting still uses modular elements to enhance the speed of construction, but the common trend of all the research institutes is the integration of the functional components within the fabric of the structure. The ability to offer new architectural possibilities will be the major driver for this method, and it is for this reason, which stands out over and above the rest, that Mega Scale Rapid Prototyping will indeed become the future of manufacturing. Yet investment at this stage is crucial, but it is the construction industry and government who need to be convinced of this technology, not the architects, as the former are the ones who are likely to risk their investment capital. Like Aristotle states, in his discussion on causation, this is only likely to happen where “there is the goal or end in view, which animates all the other determinant factors as the best they can attain to” (Physics II, iii; 195a 24-26).

There are still material and technological barriers to overcome before this method can become more widespread, much of which has been highlighted in this paper. But once these have been fully developed, off-site Mega Scale Rapid Prototyping could become commonplace and is likely to deliver a new process for the digital age of construction.

Bibliography

Ross Overfield-Collins

It must be noted that there has been several government parties who oppose the claims from the proprietor of this technology. However one knows that using magnets which repel each other, it is possible to rotate the non-static of the two. This alone gives an insight into the potential and illustrates the point of this technology in a simplistic manner.