Digital Fabrication: Manufacturing Architecture in the Information Age
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Section 4 Modeling and Fabrication Digital Fabrication: Manufacturing Architecture in the Information Age Branko Kolarevic University of Pennsylvania, USA Abstract This paper addresses the recent digital technological advances in design and fabrication and the unprecedented opportunities they created for architectural design and production practices. It investigates the implications of new digital design and fabrication processes enabled by the use of rapid prototyping (RP) and computer-aided manufacturing (CAM) technologies, which offer the pro- duction of small-scale models and full-scale building components directly from 3D digital models. It also addresses the development of repetitive non-stan- dardized building systems through digitally controlled variation and serial dif- ferentiation, i.e. mass-customization, in contrast to the industrial-age para- digms of prefabrication and mass production. The paper also examines the implications of the recent developments in the architectural application of the latest digital design and fabrication technolo- gies, which offer alternatives to the established understandings of architectural design and production processes and their material and economic constraints. Such critical examination should lead to a revised understanding of the historic relationship between architecture and its means of production. Keywords Digital Fabrication, Computer-Aided Manufacturing, Digital Construction 268 2001: ACADIA Digital Fabrication: Manufacturing Architecture in Branko Kolarevic the Information Age 1 Introduction 2 Fabrication “Integrating computer-aided design with computer-aided The continuous, highly curvilinear surfaces that fabrication and construction [...] fundamentally redefines feature prominently in contemporary architecture the relationship between designing and producing. It elimi- brought to the front the question of how to work nates many geometric constraints imposed by traditional out the spatial and tectonic ramifications of such drawing and production processes—making complex curved non-Euclidean forms. For many architects, shapes much easier to handle, for example, and reducing trained in the certainties of the Euclidean geom- dependence on standard, mass-produced components. [...] It bridges the gap between designing and producing that opened etry, it was the issue of constructability that brought up when designers began to make drawings.” into question the credibility of spatial complexi- ties introduced by the new “digital” avantgarde. - W. Mitchell and M. McCullough in Digital Design Media However, the fact that the topological geometries The Information Age, like the Industrial Age be- are precisely described as NURBS (Non-Uni- fore it, is challenging not only how we design form Rational B-Splines) and thus buildings, but also how we manufacture and con- computationally possible also means that their struct them. In the conceptual realm computa- construction is perfectly attainable by means of tional, digital architectures of topological, non- computer numerically controlled (CNC) fabrica- Euclidean geometric space, kinetic and dynamic tion processes, such as cutting, subtractive, addi- systems, and genetic algorithms, are supplanting tive, and formative fabrication, which are described technological architectures. Digitally driven de- in more detail in this section. sign processes characterized by dynamic, open- ended and unpredictable but consistent transfor- 2.1 2D Fabrication mations of three-dimensional structures are giv- CNC cutting, or 2D fabrication, is the most com- ing rise to new architectonic possibilities monly used fabrication technique. Various cut- (Kolarevic 2000). The generative and creative ting technologies, such as plasma-arc, laser-beam, potential of digital media, together with manu- or water-jet, involve two-axis motion of the sheet facturing advances already attained in automotive material relative to the cutting head and are imple- and airplane industries, is opening up new dimen- mented as a moving cutting head, a moving bed, sions in architectural design. The implications are or a combination of the two. In plasma-arc cut- vast, as “architecture is recasting itself, becoming ting an electric arc is passed through a compressed in part an experimental investigation of topologi- gas jet in the cutting nozzle, heating the gas into cal geometries, partly a computational orchestra- plasma with a very high temperature (25,000F), tion of robotic material production and partly a which converts back into gas as it passes the heat generative, kinematic sculpting of space,” as ob- to the cutting zone (Figure 1). In water-jets, as served by Peter Zellner in “Hybrid Space” (1999). their name suggests, a jet of highly pressurized water is mixed with solid abrasive particles and is It was only within the last few years that the ad- forced through a tiny nozzle in a highly focused vances in computer-aided design (CAD) and com- stream, causing the rapid erosion of the material puter-aided manufacturing (CAM) technologies in its path and producing very clean and accurate have started to have an impact on building design cuts (Figure 2). Laser-cutters use a high-intensity and construction practices. They opened up new focused beam of infrared light in combination opportunities by allowing production and con- with a jet of highly pressurized gas (carbon diox- struction of very complex forms that were until ide) to melt or burn the material that is being cut. recently very difficult and expensive to design, There are, however, large differences between produce, and assemble using traditional construc- these technologies in the kinds of materials or tion technologies. The consequences will be pro- maximum thicknesses that could be cut. While found, as new digitally driven processes of design, laser-cutters can cut only materials that can ab- fabrication and construction are increasingly chal- sorb light energy; water-jets can cut almost any lenging the historic relationship between archi- material. Laser-cutters can cost-effectively cut tecture and its means of production. material up to 5/8”, while water-jets can cut much 2001: ACADIA 269 Section 4 Modeling and Fabrication thicker materials, for example, up to 15” thick ti- vals, are produced automatically by modeling soft- tanium. ware from a given form and can be used directly The production strategies used in 2D fabrication to articulate structural components of the build- often include contouring, triangulation (or polygo- ing, as was the case in a number of recently com- nal tessellation), use of ruled, developable surfaces, and pleted projects (Figures 3 and 4). unfolding. They all involve extraction of two-di- Complex, curvilinear surface envelopes are often mensional, planar components from geometrically produced by either triangulation (or some other complex surfaces or solids comprising the planar tessellation) or conversion of double-curved into building’s form. Which of these strategies is used ruled surfaces, generated by linear interpolation depends on what is being defined tectonically: between two curves (Figures 5 and 6). Triangu- structure, envelope, a combination of the two, etc. lated or ruled surfaces are then unfolded into pla- In contouring, a sequence of planar sections, often nar strips, which are laid out in some optimal fash- parallel to each other and placed at regular inter- ion as two-dimensional shapes on a sheet (in a process called nesting), which is then used to cut the corresponding pieces of the sheet material using one of the CNC cutting technologies. For example, Frank Gehry’s office used CATIA soft- ware in the Experience Music Project in Seattle to “rationalize” the double-curved surfaces by Figure 1. Plasma-arc CNC cutting of steel supports for masonry walls in Frank Gehry’s Zollhoff Towers in Dusseldorf, Germany (Rempen 1999). Figure 3. Structural frames in Frank Gehry’s Experience Music Project in Seattle, produced by contouring. Figure 2. Aluminum space frame for ABB Architects’ BMW Pavilion is cut directly from digital data using CNC water-jet Figure 4. Structural framework for Bernard Franken’s BMW technology. Pavilion produced by bi-directional contouring. 270 2001: ACADIA Digital Fabrication: Manufacturing Architecture in Branko Kolarevic the Information Age converting them into “rule-developable” surfaces, of excessive curvature as there are limits as to how which were then unfolded and fabricated out of much the sheets of metal could be bent in two flat sheets of metal (Linn 2000). directions; the same technique was used on other The surface data could be also used to directly projects by Gehry (Linn 2000). The analysis pro- generate a wireframe abstraction of the building’s duced a colored image that indicated through vari- structural framework, which could be then pro- ous colors the extent of the surface curvature (Fig- cessed by the structural analysis software to gen- ure 7). erate the precise definition of all structural mem- 2.2 Subtractive Fabrication bers. In Gehry’s Bilbao project the contractor used Subtractive fabrication involves removal of speci- a software program from Germany called Bocad fied volume of material from solids (hence the to automatically generate a comprehensive digi- name) using multi-axis milling. In CNC (Com- tal model of the structural steel, including the puter Numerical Control) milling a dedicated brace-framed and secondary steel structures for computer system performs the basic controlling the museum (Stephens 1999).