Articles

    Chapter Platinum Sponsor, M.G. McGrath, September 2013: Digitally Defined Fabrication

    DIGITALLY DEFINED FABRICATION

    by Chapter Platinum Sponsor, M.G. McGrath

    Recently, the National Institute of Standards and Technology (NIST) requested that the National Research Council (NRC) appoint an ad hoc committee of experts to provide guidance for advancing the competitiveness and productivity of the U.S. construction industry. The committee’s specific task was to conduct a workshop to identify and prioritize technologies, processes and deployment activities that have the greatest potential to significantly advance the productivity and competitiveness of the capital facilities sector of the U.S. construction industry in the next 20 years. The committee identified five breakthroughs to improve the efficiency and productivity of the construction industry, including breakthrough number three: “Greater use of prefabrication, preassembly, modularization, and off-site fabrication techniques and processes."

    Digitally Defined Fabrication also was identified as part of this new standard in the construction and fabrication industry. In this brief overview, Digitally Defined Fabrication will be established, including the significance of Buidling Information Modeling (BIM) in fabrication, the advantages of Digitally Defined Fabrication, and the process of fabricating building components.


    Digitally Defined Fabrication

    As the construction industry is continually developing, design and fabrication of erection modules is becoming more prevalent in architecture. These changes and developments in the industry challenge our ideas and concepts of what is possible. These new ideas and concepts have shaped a new understanding how project material is created and consumed. Digitally Defined Fabrication has allowed for these new ideas and concepts to come to life through the use of computer-controlled fabrication. Data files are generated using software, such as SolidWorks® and Autodesk® Revit, delivering data from computers to machines allowing for complete control over geometries and tolerances on each of the building components.

    The use of the Digitally Defined Fabrication methods produce opportunities for enhanced collaboration among architects, fabricators and contractors, permitting them to all work from the same centralized file called "theory" in a BIM model. It is significant that each team member builds to that same theoretical location for the project to come together to its entirety on time and on budget. The coordinated data within a completely well-versed BIM model advances the constructability, decreases the cost and empowers design innovations for crafting unique structural components.


    BIM Models in Fabrication

    The use of BIM to support digital prototyping has spurred a design revolution allowing for innovations in the architectural industry. By applying BIM models to buildings, project teams can understand a project, digitally, prior to being built. BIM allows for simulation of performance and constructability, as well as interrelating and interpreting the designs intent. The information encircled in these models is applied to generate instructions for digitally fabricating building elements and this enables cost-effective fabrication of custom designed components.

    BIM allows for fabrication to occur off-site of many types of building components and is becoming progressively collective in driving the necessity to apply advanced processes in the construction industry. These building components include steel framing, curtain walls, facades and building envelope designs, as well as mechanical and piping assemblies. While BIM Digitally Defined Fabrication is in its preliminary phase of gaining traction in construction, the potential to convey productivity gains and advantages are becoming increasingly perceived in the benefits that are delivered to the building industry.


    Advantages of Digitally Defined Fabrication

    Digitally Defined Fabrication and pre-fabrication methods systematically offer numerous advantages in contrast to the on-site, piece-built approach that is commonplace in the construction industry currently. These advantages include, but are not limited to, cost savings, reduced labor schedules, enriched quality and control of tolerances, and enhanced coordination amongst architects, fabricators and builders.

    Cost savings in Digitally Defined Fabrication permits for repetitive components to be prefabricated off-site with the utmost controls of all tolerances involved in the project. These precisions of building components reduce waste and condense construction time. The reduction in labor schedules due to the off-site prefabrication diminishes on-site interferences, as well as decreases lead times; facilitating faster erection and placement of building components on a project. Digitally Defined Fabrication furthermore allows for the enriched quality and control of tolerances via information extracted directly from the BIM project model, reducing errors caused by miscommunication or misinterpretation of the design. The quality of fabricated components generated in controlled settings is superior to those generated on-site. More importantly, the use of Digitally Defined Fabrication allows for enhanced coordination amongst architects, fabricators and contractors, allowing for the theory of the BIM model to be achieved successfully.


    The Process of Fabricating Building Components

    Fabricators acquire schematic designs of the BIM model in the early stages of a new building project from the architect. Fabricators work collaboratively with the architect to create precise shop drawings for the components of the building. Once shop drawings are approved, field measurements are taken so that the building components can be configured with precision that will be essential to complete the project, without having the need to make modifications at the job site. In terms of the building component functions, accurate shop-optimized drawings are crucial. This allows for the raw material to be manipulated to the requirements of the project. To avoid miscommunication or misinterpretation of the design in the fabrication, it is important that communication lines are kept open amongst all those that are involved in the project including the architects, fabricators and contractors.

    Prefabrication, preassembly, modularization and off-site fabrication involve the assembly or fabrication of building systems and/or components at off-site locations. Once completed, the systems or components are shipped to a construction job site for installation. Prefabrication and related techniques allow for the following:
    1. More controlled conditions for weather, quality, improved supervision of labor and fewer material deliveries
    2. Fewer jobsite environmental impacts because of reduction in material waste, air and water pollution, dust and noise and overall energy costs
    3. Compressed project schedules
    4. Fewer conflicts in crew scheduling and better sequencing of work
    5. Reduced requirements for on-site storage
    6. Increased worker safety through reduced exposure to inclement weather and better working conditions.

    Greater use of prefabrication, preassembly, modularization and off-site fabrication techniques and processes is becoming increasingly common practice. The integration of Digitally Defined Fabrication on projects is paramount to any lean construction process. Bringing together multiple trades for a prefabrication project can be problematic in traditional construction, but through BIM-enabled coordination and team integration -- it is not only possible, it is essential. The industry needs to change, and although prefabrication is a technique that is often driven by specialty contractors, the construction industry as a whole needs to understand and adopt prefabrication and related techniques to create lower project costs, shorter schedules, improved quality, more efficient use of labor and materials, and improved worker safety.