Rapid Prototyping in Architecture

It is not too farfetched to predict that in the future a complete building will be built from a computer. Similar technology has already begun to be used by the industrial design and manufacturing industries. One of the best-known and oldest technologies is called Stereo Lithography, because it involves a laser beam moving through a vat of ultraviolet-sensitive liquid polymer, which follows the contour of a digital 3D model. The beam strikes on a layer of ultraviolet-sensitive liquid polymer, and then the thin layer is solidified. The laser will keep repeating the same process from the bottom to the top of the 3D model. A temporary framing support for the model is required, because the process is from the bottom up. Stereo Lithography machines are manufactured by 3D Systems Inc., and they are also known as Stereo Lithography Apparatuses (SLA). The final model usually requires a little bit of sanding, and it is inappropriate for an office setting because this process produces toxic fumes. The following is a list of processes that may assist the automation of the building industry. These existing technologies can immediately assist the building industry; however they do require some modification to suit individual building types. It should be noted that these manufacturing processes are crucial to the development of building automation. Computers can produce precise results, while manual labor is imprecise. The direct digital manufacturing process can reduce errors and make digital building components affordable. The original prototype is always costly, but the cost can be reduced to a bare minimum by using rapid prototyping processes.

Rapid prototyping (RP) is a digital modeling process, which is a real physical model of a component (in prototype form) that is entirely created directly from a 3D CAD drawing. RP systems generate quick prototypes by constructing an additive and layer-by-layer process that is driven by 3D CAD data. RP is also known as desktop manufacturing or free-form fabrication. RP machines require STL data files, which are generated by the CAD system. An STL file is a data file format designed specifically for rapid prototyping machines. Any rapid prototyping system can use the STL file from any type of 3D CAD system that outputs the STL data. RP machines operate quite differently than typical CNC machines. RP machines are subtractive in nature, because they join together liquid, powder and sheet materials to form complex forms. Using layer-by-layer technology, RP systems fabricate plastic, wood, ceramic or metal objects based on several cross-sections from a 3D CAD model.

RP cannot be mistaken by rapid manufacturing (RM) or rapid tooling (RT); however, all the above mentioned processes involve 3D CAD files. RM is a rapid manufacturing process. RM is an ultimate process that manufactures parts directly from a computer. The benefits of any rapid processes are that fewer steps are required to achieve the final result and that

The original prototype is always costly, but the cost can be reduced they are much faster than the traditional methods. According to Wohlers, some companies are beginning to use rapid prototyping technologies to manufacture finished parts. Most of these applications are geared to small quantities of parts, because there are still some technical difficulties for RM in reaching the production capacity of injection molding, die-casting, or sheet metal stamping at the time of this publication. These technical difficulties are: inferior surface finishes to production molded parts; inadequate dimensional accuracy and repeatability; durability and cooling efficiency; small limited part sizes; and the time and expense associated with removing excess resin and performing post curing operations. "These applications are proving that rapid prototyping can be suitable for production in terms of speed, material properties, accuracy, and surface finish. Moreover, rapid prototyping of mechanical CAD designs is well established and will continue to grow. Soon many other applications will follow suit. Indeed, organizations will rely on the technology for sculpture, architecture, mold flow analysis, molecular modeling, forensic analysis for solving crimes, and a variety of uses yet to be conceived."1

RAPID PROTOTYPING
Stereo Lithography Apparatus (SLA) - This is the oldest (discovered in the late 1980s) and most common technology. It involves a laser beam moving through a vat of ultraviolet-sensitive liquid polymer which follows the contour of the digital 3D model. The beam strikes on a layer of ultraviolet-sensitive liquid polymer, and then the thin layer is solidified. The laser will keep repeating the same process from the bottom to the top of the 3D model. A temporary framing support for the model is required, because the process is from the bottom up. Stereo Lithography machines are manufactured by 3D Systems Inc. The final model usually requires a little bit of sanding, and it is inappropriate for an office setting because this process produces toxic fumes. SLA is simple, fast and accurate.

Idea Applications

* Prototype or Presentation Model a quick, fast, and concise process for conveying the design intent. SLA is inappropriate for creating the final form, because the end result is highly fragile.
Object 3D printing - this process uses ink-jet technology with photo polymer resins. The ink-jet like head drops fine deposits of resin while a UV lamp cures these droplets immediately. Object 3D printing is also a layer-by-layer process. Objects created by 3D printers are highly detailed and accurate. No sanding is required, because the object is cleaned with a low-pressure water jet in the process.

* Appropriate for architectural model

* Form and fit analysis

* Concept and presentation models

* Sales and marketing samples

* Tooling patterns

Z Corporation's 3D printer - The Z Corporation's 3D printer works by creating physical 3D models directly from digital data, layer by layer. A part can be printed at the rate of 25mm (1") vertical per hour. It is fast, versatile and simple comparing to other similar systems, allowing architects/engineers to produce a range of concept models and functional test parts quickly and inexpensively. The system is ideal for an office environment or educational institution, providing product developer's easy access to a 3D Printer. "A 3D CAD file is imported into the proprietary system software. The software slices the file into thin cross sectional slices, which are fed to the 3D Printer. The 3D Printer creates the model one layer at a time by spreading a layer of powder and ink-jet printing a binder in the cross-section of the part. The process is repeated until every layer is printed and the part is complete and ready to be removed."2

Idea Applications

* Ideal for conceptual models, architecture models, and functional testing prototypes

* Require Z-bond solution to make the component stronger.

* Can be used to make strong, high-definition parts and is the material of choice for printing color parts.

* Can be used to quickly fabricate parts that can be dipped in wax to produce investment casting patterns.

* Can be used to create sand casting molds for non-ferrous metals.

* Has been optimized for infiltration with Z-Snap epoxy to create
parts with plastic-like

When the search for a rapid tooling solution begins, it is common to use traditional tooling techniques as the benchmark. The goal becomes the replication of all the quality of a cut tool while slashing the delivery time and expense. With these standards, the options become limited. These imposed limitations can make it best to seek out a tool shop that is extremely fast and efficient at building cut tools in aluminum or steel. In the evaluation of projects, Accelerated Technologies often finds that a machined tool is a far superior solution.
Under the original, narrow definition, rapid tooling has limitations in many areas. These include:

* Tool life

* Accuracy

* Surface finish

* Resin selection

* Tool configuration

* Cycle time

* Part size

Each available rapid tooling solution presents limitations in at least two of these areas. When the strengths and weaknesses of the processes are presented, many elect to use traditional methods that may require more time. It certainly will be a dream comes true if technology brings down cost of buildings. Shopping for a designer house will be one of the choices open to everyone, not the privilege of a few. A 10 to 15 year recycling time for a house will be appropriate, because the recycling cost will be lower than the renovation cost.

Fast prototyping cannot replace our current building practice, but at least it will help to construct a mock-up to improve the design. It is a known fact that a full-size building mock-up is necessary to eliminate errors and the need for future design modifications. Fast prototyping can accelerate the mock-up process, bring down the cost, and speed up the final construction time.

Full-size building component prototypes are not yet in production, because they require detailed connections and some modifications. It is not hard to imagine, that in the near future an entire house will be manufactured by an LOM machine or other RP processes directly. Such a notion is exciting and will revolutionize the building industry. Rapid tooling is a powerful process that can definitely make the building process faster, cheaper, and better.  If you find this article interesting, and want to find out more about how emerging technologies change the field of architecture.  Please go to Amazon.com or barnsandnoble.com to check out Mr. Chang’s new book- Making of Digital Forms: A Study in Emerging Technologies in Architecture.

Footnotes
1) Wohlers, Terry, Computer Graphics World, November, 2001

2) ZPrinter 310 Plus Brochure, www.zcorp.com, March, 2008