Compared to approaches of mass customization in consumer products or furniture, there are usually few if any direct connections between the architectural product configuration software and the digitally driven manufacturing process. The traditional distribution of responsibilities between the design team and the contractors or fabricators makes any degree of automation between design and production presently a journey into legal no-man's-land.
Shop drawings exist for many good reasons and cannot easily be eliminated. The need to verify whether an architectural product or component is correctly designed and meets code clearly sets apart all attempts for mass customization with their counterparts in product design.
Verifying whether an architectural product and its components meets code, represents the design intention, and can be manufactured is usually a much more complex undertaking involving a number of independent parties. There is usually no one party that is expert in all areas, and this specialization necessarily creates a need for design verification.
Typically a given design environment has to be able to communicate with manufacturing facilities at many different companies. This makes any direct integration extremely difficult to achieve. A further problem in the building industry is its fragmentation: Fabricators are often small to midsize companies, and the production volumes necessary to generate the economy-of-scale effects in a modularized production setting of mass customization are normally missing.
The Architectural Skylight Company(ASC) of Waterboro, Maine uses an object-oriented design approach to designing and manufacturing custom skylights. This system supplements AutoCAD with several plug-ins, including third-party software and programs developed by ASC. It allows technicians to import geometry generated by the architects, build upon this model, and generate a complete model of the skylight or curtain-wall parametrically in 3D.
The same model, after several post-processing steps, is used directly for computer numerical control (CNC) manufacturing of frame members and for the CNC cutting of custom glass sheets.
With this integrated approach to design and manufacturing well established and proven, ASC has sought to expand its market by setting up a system capable of producing smaller skylights for small to medium-size commercial and residential construction.
An online interface was set up, allowing customers to design custom skylights within the given manufacturing constraints. Within two and a half years of its implementation, over 65,000 skylights were designed online. The system is mostly used by glazing contractors, but also by architects and individual homeowners.
Online Design Process
The online design interface is structured into a series of simple steps that, at each level, enables a choice between either preselected options or the input of dimensions or desired performance values. The design process starts with a selection among the four basic types.
In the following steps all other parameters are defined, beginning with the basic dimensions, followed with a selection of frame and glass qualities and finishes. In case the user specifies dimensions that are beyond the range of the supported modularized product line, the system prompts an alert and points to the closest possible value.
During the design process, an image displays a photorealistic rendering of the specific configuration. A quote for the custom skylight is instantly available online based on the 3D model in the AutoCAD-based environment.
This same model is eventually used to generate machine instructions for fabrication; it is also used to derive the bill of quantities, specifications, and all 2D drawings. Users can download the specifications, overview drawings, and construction details — all representing the specific version chosen during the online design session.
Once the desired skylight is ordered, the glass dimensions are automatically generated from the 3D model and electronically sent as text and drawing files to the glass fabricator. The desired glass type and coating are also included in this order, again derived from the bill of materials generated by the 3D model.
To minimize storage costs, ASC does not store aluminum profiles in all available finishes. Once a skylight has been purchased, an affiliated metal finishing company automatically receives the order to finish a certain amount of a particular frame profile. This customized stock is then sent to ASC "just in time" for subsequent machining.
Before any machining of metal profiles, the software system creates a set of printed 2D fabrication or shop drawings that are used for quality control, to guide the assembly of the unit in the shop, and to support the installation on site.
The code is automatically generated from the 3D model and sent to one of the machining centers. The programming computer-aided manufacturing (CAM) software includes nesting routines that optimize material use of the customized frame stock. Technicians check the fabricated parts to the 2D fabrication drawings.
A barcode system is employed throughout the manufacturing process to track each part during the various machining and finishing steps. Once all parts have been fabricated, units are assembled as much as possible to avoid any errors in the field and to maintain a tight quality control. Custom skylights are generally shipped within four weeks of the purchase.
Business Paradigm of the Future?
One of the main challenges of mass customization is the need to be cost-competitive with equivalent mass-produced items. This objective can only be achieved if the complete design-to-delivery process is highly streamlined to eliminate any potential inefficiency.
For customized architectural products or components, the industry-specific fragmentation is a major obstacle to mass customization. Only a few companies have successfully transitioned into mass customization, and with few exceptions those usually had a well-established position in niche markets or were, such as the large window manufacturers, among the market leaders in their field.
Most of the successful mass customizers also pursue another business model at the same time — the manufacture of standard windows or, in the case of ASC, designing and building high-end custom products for large projects. This diversification, and potential of transferring know-how between related production modes, is probably another reason for their success.
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Daniel Schodek is the Kumagai Professor of Architectural Technology at the Harvard Design School, where he taught CAD/CAM classes for many years. He is the author of Structures, Fifth Edition,the leading text in the field, and several other books. His coauthors also teach at the Harvard Design School.
This article is excerpted from Digital Design and Manufacturing: CAD/CAM Applications in Architecture, copyright © 2004, available from John Wiley & Sons and at Amazon.com.