Full factory fit-outs are conceivable using DfMA and where this isn’t feasible, the objective is to find solutions whereby the majority of the fabrication occurs in a factory.
Modelling demonstrates DfMA’s emphasis on improving the quality of the design and process.
Design for manufacture and assembly (DfMA) is a process adopted in prefabricated building whereby systems are designed to include components that may be manufactured individually and that are assembled either in a factory or on site. This is a substantially different paradigm from traditional approaches to construction and requires a holistic re-think of the conventional design and build. However there are many advantages of embracing DfMA when seeking to achieve resource-efficient and cost-effective solutions that translate to a competitive advantage in the building and construction industry. CAMPH is researching DfMA concepts as part of its effort to boost prefabricated construction in Australia.The shift from on-site construction to manufacturing and assembly requires a substantial change in the project workflow with a strong emphasis on the design and planning phase. All issues must be resolved prior to components being manufactured so that problems are not encountered on the assembly line, which can be costly and result in considerable project delays. Early engagement of the manufacturer during this phase is important so that they can discuss practicalities associated with transport, cranage, assembly, installation sequence and on-site connection of components.
Researchers at ARC-CAMPH are considering how DfMA may be become part of advanced prefabricated systems. There are three streams of research in ARC-CAMPH incorporating DfMA: innovation in design and enhanced end-user experience, novel materials and composite structures, and advanced building systems and assembly techniques. Some of the research is focusing on developing a “main frame” for a structure, a concept famously conceived by architect Renzo Piano. The concept involves a universal framing system developed for different building categories that is combined with sub-modules or attachments for installation within the universal framing system. The sub-modules may be planar systems such as wall panels and floor cassettes, or volumetric systems such as bathroom pods. There is a practical limit for the degree of prefabrication however, whereby the capabilities of prefabricated construction are outweighed by the ability to customise on-site. The weight of a module is a primary consideration for cranage when assessing the feasibility of a given system, therefore a full factory fit-out may not be achievable. A hybrid methodology is often deemed a suitable compromise whereby the majority of the fabrication occurs in a factory and the remainder occurs on-site. This philosophy also enables limited modifications to the structure to accommodate conditions encountered on site that are difficult to predict during design.
Design is interlinked with assembly requirements and therefore manufacturing capabilities. In order to minimise the complexity of assembly and reduce resources required on-site, it is necessary to reduce the number of assembly operations, adopt self-locating and self-fastening features and standardise and integrate modular parts wherever possible. The challenge is to develop a system that is highly standardised yet offers sufficient customisation that buildings appear individually designed. This is a particular challenge when seeking to achieve mass customisation. The emphasis of the manufacturing component is on reducing product cost whilst improving quality of the design and process. Modulum Homes is a company partnered with ARC-CAMPH that has developed a system involving these principles. Their system involves pre-cut and pre-drilled components resulting in a build time that is reduced by one-third relative to traditional building methods. The peak body for the off-site construction industry, prefabAUS, has many members employing DfMA as part of their operations. BIM is another key area of research within ARC-CAMPH and is recognised as an ideal partner to DfMA, having many benefits related to quality and efficiency as well as facilitating greater collaboration with the supply chain. BIM offers a common platform among architects, designers, engineers and the supply chain to not only streamline manufacture, but also to better service and maintain the asset throughout its design life. However, it should not be perceived as a panacea to assembly issues. As an example, all components will have a geometric tolerance that may accumulate during on-site assembly due to human error. Therefore, manual intervention via checks and continual on-site monitoring is prudent.
“The shift from on-site construction to manufacturing and assembly requires a substantial change in the project workflow with a strong emphasis on the design and planning phase. All issues must be resolved prior to components being manufactured so that problems are not encountered on the assembly line, which can be costly and result in considerable project delays.”
David Heath – CAMPH
The technologies being developed at CAMPH may also be used to build highly sophisticated facilities such as those used by health care and defence. The University of Melbourne has an extensive experience in protective structures research for the defence sector. The integration of this work with prefabricated construction offers new possibilities for rapidly deployable mobile facilities that house high tech equipment.
It is imperative that advanced manufacturing, particularly operations employing DfMA, have an efficient supply chain. The Advanced Manufacturing Growth Centre’s Sector Competitiveness Plan 2017 reports that Australia’s manufacturing industry is only weakly linked with the global supply chain for foreign inputs to generate goods and services for export. Moreover, it notes that “Australian manufacturers are missing opportunities to reduce costs, to drive innovation through the transformation of inputs, and sell into new markets.” Some manufacturers have already explored technologies available through the global supply chain. One example is Envirosip, an industry partner to ARC-CAMPH that is sourcing materials internationally, then locally manufacturing highly durable panelised systems for prefabricated construction.
DfMA is particularly pertinent in light of the new paradigm for manufacturing in Australia which focuses on increased productivity. Factory-based semi-automated production lines have been estimated to offer three times the level of productivity relative to comparable site-based construction. Sophisticated semi-automated production lines are being employed in Australian prefabrication companies such as Timber Building Systems, an industry partner of ARC-CAMPH. State-of-the-art production line systems are available off the shelf from manufacturers such as Weinemann, Randek and Hundegger. While costly manufacturing technologies are often considered a barrier to entry to the prefabricated buildings market, it has been demonstrated that investments in technology are strongly associated with increased competitiveness. The Advanced Manufacturing Growth Centre’s Sector Competitiveness Plan 2017 notes that the manufacturing firms in the top 25% for productivity exhibit 3.17 times the R&D intensity relative to their counterparts in the bottom 25%, and 1.75 times the number of patents.
The effective use of DfMA in prefabricated construction is therefore an avenue to not only increase productivity but also to increase the competitiveness of Australia’s prefabrication industry. The global prefabricated buildings market is vast and there are increasing opportunities to participate. A report titled ‘Global Prefabricated Buildings Market – Key Trends and Opportunities to 2017’ found the Asia-Pacific prefabricated buildings market in 2012 was valued at US$44.4b. While China’s share of this market was 61%, Australia’s share was only 6.8%. The report also estimated the global prefabricated market to be valued at $US90.1b. The Beijing Municipal Commission of Housing and Urban-rural development recently announced that Beijing is seeking to conserve energy, improve efficiency and upgrade the building industry by setting a target of 30% of new buildings being prefabricated by 2020. This initiative is accompanied by supporting measures including proposed tax cuts, improved project approvals, and financial support by the government.
In light of these global developments, here is increasing pressure to increase productivity and deliver lower price projects in the building industry. Prefabricated construction employing DfMA offers the ability to enhance confidence in project schedules whilst reducing budgets and timeframes. Sophisticated digital technologies are playing an important role in achieving this outcome and newer technologies on the horizon such as additive manufacturing and automation are poised to advance the industry even further. Through research projects and training activities that partner postdocs and PhD candidates with prefab companies, the ARC Centre for Advanced Manufacture of Prefabricated Housing is exploring how DfMA and other technologies can benefit our building and construction industry.■