1
Design for Manufacture and Assembly (DfMA) in construction: the old and 1
the new 2
Weisheng Lu
1
, Tan Tan
2*
, Jinying Xu
3
, Jing Wang
4
, Ke Chen
5
, Shang Gao
6
, and Fan Xue
7
3
4
This is a copy of the peer-reviewed Accepted Manuscript of the paper:
Lu, W., Tan, T., Xu, J., Wang, J., Chen, K., Gao, S. & Xue, F. (2020). Design for
Manufacture and Assembly (DfMA) in construction: The old and the new.
Architectural Engineering and Design Management, in press. Doi:
10.1080/17452007.2020.1768505
This document is available for personal and non-commercial use only, as permitted by
Taylor & Francis Group’s Architectural Engineering and Design Management. The final
version is available online: http://www.tandfonline.com/10.1080/17452007.2020.1768505
5
Abstract 6
Design for manufacture and assembly (DfMA) has become a buzzword amid the global 7
resurgence of prefabrication and construction industrialization. Some argued that DfMA is 8
hardly new, as there are concepts such as buildability, lean construction, value management, 9
and integrated project delivery in place already. Others believe that DfMA is a new direction 10
to future construction. This paper aims to review the development of DfMA in manufacturing 11
and its status quo in construction, and clarify its similarities and differences to other concepts. 12
A multi-step research method is adopted in this study: First, an analytical framework is 13
generated; Secondly, a literature review is conducted on DfMA in general, and DfMA-like 14
concepts in the AEC industry; The third step is to compare DfMA with related concepts. This 15
study reveals that DfMA as a philosophy is hardly new in construction, and the empirical 16
implementation of many DfMA guidelines has begun in the AEC industry. The findings 17
suggested that DfMA is a new and mixed ‘cocktail’ of opportunities and challenges to 18
improve construction productivity with the advancement of construction materials, production 19
and assembly technologies, and ever-strengthened logistics and supply chain management. 20
This study sheds light on three research directions: DfMA implementation and guidance 21
strategies, DfMA frameworks and blueprints, and applications in cast in-situ or intermediate 22
prefabrication construction. Our research findings provide a synopsis of DfMA research and 23
development in construction. This paper can also serve as a point of departure for future 24
theoretical and empirical explorations. 25
26
Keywords: Design for manufacture and assembly; Construction Industrialization; 27
Prefabrication; Construction 28
29
1
Professor, Department of Real Estate and Construction, The University of Hong Kong, Hong Kong, e-mail:
wilsonlu@hku.hk
;
2
PhD Student, Corresponding Author, The Bartlett School of Construction & Project Management, University College
London, London, e-mail: tan.tan.17@ucl.ac.uk
, Tel.: +44(0) 77 1614 8651;
3
PhD Candidate, Department of Real Estate and Construction, The University of Hong Kong, Hong Kong, e-mail:
jinyingxu@connect.hku.hk
;
4
PhD Candidate, Department of Real Estate and Construction, The University of Hong Kong, Hong Kong, e-mail:
jingww@connect.hku.hk
;
5
Associate Professor, Department of Construction Management, Huazhong University of Science and Technology, e-mail:
chenkecm@hust.edu.cn
;
6
Lecturer, Faculty of Architecture, Building and Planning, The University of Melbourne, Australia, e-mail:
shang.gao@unimelb.edu.au;
7
Assistant Professor, Department of Real Estate and Construction, The University of Hong Kong, Hong Kong, e-mail:
xuef@hku.hk
;
2
1. INTRODUCTION 30
Design for manufacture and assembly (DfMA) is an emerging approach in the global 31
architecture, engineering, and construction (AEC) landscape. In 2013, the Royal Institute of 32
British Architects (RIBA) published a Plan of Work for DfMA implementation. In 2016, 33
Singapore’s Building and Construction Authority (BCA) issued an official guide facilitating 34
DfMA and its incorporation with Building Information Modeling (BIM). In 2018, the UK 35
government’s Infrastructure and Projects Authority published a revised National Infrastructure 36
and Construction Pipeline detailing its preference for the Platform Method for Manufacturing 37
and Assembly Design. The report also publicized its use for prefabrication and other offsite 38
construction methods in public projects. The Hong Kong government’s 2018 document 39
Construction 2.0 also emphasises the importance of DfMA. In the research realm, the DfMA 40
literature is growing, while industry leaders such as O’Rourke (2013) and Balfour Beatty (2018) 41
consider DfMA to be the future of construction. 42
But is DfMA merely old wine in a new bottle? According to Boothroyd (2005), DfMA 43
evaluates and improves product design by considering the downstream processes of 44
manufacturing and assembly. Similar if not identical concepts have been introduced to improve 45
AEC productivity and efficiency. For example, buildability assesses designs from the 46
perspective of those who will manufacture and install components and carry out the 47
construction work (Lam and Wong, 2009); lean construction adapts the concept of lean 48
production/manufacturing to the AEC industry with a view to maximising value and 49
minimizing waste (Koskela, 1992; Alarcón, 1997). Value management (VM) focuses on the 50
early design stage and advocates achieving value for money by deliberating over functions and 51
costs (Kelly et al., 2004; Shen and Liu, 2004), with downstream manufacturing and assembly 52
within the critical scope of the exercise. 53
This paper aims to clarify the concept of DfMA in the AEC industry. First, we review 54
the literature on its history in the manufacturing industry and current DfMA developments in 55
construction. The research then goes on to compare DfMA with the concepts mentioned above 56
to find their similarities and differences. Based on the review and comparisons, this study 57
further provides prospects and challenges for DfMA. The remainder of the paper is organized 58
as follows. Section 2 is a detailed description of the research methodology. Section 3 is an in-59
depth analysis of the DfMA research, while Section 4 compares DfMA with similar concepts 60
with a view to answering the key question of this study. Section 5 articulates the prospects and 61
challenges of DfMA, while conclusions are presented in Section 6. 62
63
2. METHODOLOGY 64
A multi-step research method consisting of brainstorming, literature review and in-depth 65
comparative analyses is adopted in this study. First, given the long history of DfMA 66
development, an analytical framework is required to demarcate a reasonable research boundary 67
and guide the analyses. Since DfMA has only recently been popularized in construction, this 68
research includes DfMA-like construction concepts (e.g., fabrication-aware design) to allow it 69
to be fully investigated. Brainstorming, as a creative training method, can find a set of practical 70
solutions through objective and continuous analysis of the issues discussed (Rawlinson, 2017). 71
To establish the analytical framework for this study, an hour-long brainstorming session was 72
held. Six researchers from different disciplines participated, all with at least six years’ research 73
experience in the AEC industry and two with around 10 years’ experience in engaging with 74
construction prefabrication in China and Hong Kong. Taking into account the possible bias of 75
brainstorming, this step is only used to determine the scope of the discussion without having a 76
conclusive effect on the outcome of the discussion. As a result of the session, the scope of the 77
study was limited to seven broad DfMA-related categories: origins, definition, processes, 78
3
guidelines, comparisons, prospects, and challenges. The analytic framework developed is 79
shown in Figure 1. 80
81
82
Figure 1 DfMA in construction: an analytic framework 83
84
Second, guided by this framework, a search was conducted for the relevant literature on 85
DfMA in general, as well as DfMA-like concepts in the AEC industry specifically, using the 86
bibliographic database Google Scholar. Keywords used in article selection included ‘design for 87
manufacture and assembly’, ‘design for manufacture’, ‘design for assembly’, ‘DfMA’, 88
‘fabrication-aware design’, ‘architectural geometry’, ‘architectural design’, ‘construction’, 89
‘assembly’, ‘construction industry’, and ‘AEC’. These keywords were adopted to reflect usages 90
across research disciplines and countries. For example, architecture researchers prefer 91
‘fabrication’, while in engineering ‘manufacture’ is used to describe the building production 92
process. Mathematicians try to use architectural geometry to bridge the gap between complex 93
architectural design and applicable construction. Year of publication was limited to the period 94
2009 to 2019 to capture the latest DfMA research and trends in AEC. A total of 1979 results 95
were generated from the initial search. Then, the strict filtered process was conducted to narrow 96
down the scope of target articles. Articles that included related key terms in the 97
title/summary/keyword were considered for review, and only journal articles were selected to 98
ensure that all retrieved articles could be analyzed by using the same analytical structure as their 99
research objectives and methods. A snowball technique (Lecy and Beatty, 2012) involving 100
checking the references of the selected papers was applied to find relevant papers that may not 101
have been included. Finally, 30 publications highly related to the DfMA in the construction 102
were derived for the analysis of DfMA definition and research trend. 103
The third step was to develop an in-depth understanding of DfMA by comparing it with 104
similar concepts, such as buildability, value management, lean construction and 105
prefabrication/Modular integrated Construction (MiC). The literature on these concepts was 106
extracted and reviewed for the comparative study which mainly focused on the connotations, 107
extensions, and applications of the concepts and DfMA and analyzed their similarities, 108
differences, and linkages. These comparisons were triangulated with the past experience of the 109
authors involved in BIM and offsite construction in Hong Kong, China, and the UK. 110
111
3. DFMA: HISTORICAL DEVELOPMENT AND STATUS QUO 112
3.1 Historical development of DfMA 113
DfMA originated during World War II when Ford and Chrysler applied it as a principle in their 114
weapon production processes. At first, it was used in manufacturing industry. Formal 115
approaches to design for manufacture (DfM) and design for assembly (DfA) emerged in the 116
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late 1960s and early 1970s, reflected in UK standards published in 1975 on the management of 117
design for economic production. The academic exploration of DfMA also began in the 1970s 118
with the practice and research of Boothroyd and Dewhurst. Since then, there has been much 119
development of DfMA within the manufacturing industry. 120
According to Boothroyd (2005), DfMA provides a methodology for evaluating and 121
improving product design by considering the downstream processes of manufacturing and 122
assembly. It thereby signifies a shift from traditional, sequential design thinking to a non-linear 123
methodology. The implementation of DfA and DfM has the potential to bring considerable 124
benefits, including reducing assembly and manufacturing costs, improving quality, and 125
shortening production time by simplifying products. But these are only considerations of 126
production efficiency. Due to the requirements of sustainability, some scholars have begun to 127
consider the consideration of disassembly and recycling during the design phase. Researchers 128
are beginning to focus on the design of the environment, recyclability, life cycle, etc. These 129
studies are sometimes referred to as Design for excellence (DfX) (Kuo et al., 2001). DfX is a 130
related methodology, where the ‘X’ refers to excellence in aspects including testability, 131
compliance, reliability, manufacturability, inspection (DfI), variability (DfV), and cost (DfC). 132
DfX in general aims to provide a standard philosophy, methodologies, and tools to optimize a 133
design (Gatenby and Foo, 1990; Kuo et al., 2001; Eastman, 2012). For example, DfX techniques 134
can improve quality, efficiency, productivity and design flexibility, and decrease life-cycle 135
costs using concurrent design concepts (Maskell 1991). DfX research emphasizes the 136
consideration of all design goals and related constraints in the early design stage (Kuo et al., 137
2001). Huang (2012) describes two streams of ‘X’, one with emphasis on a particular business 138
process and the other on a performance metric. DfA falls into the former since it focuses on the 139
assembly process while using multiple performance measures (inspectability, compatibility, 140
recyclability, serviceability, etc.). Design for modularity, on the other hand, is an example of 141
the latter since it looks into modularity across several business processes from manufacturing 142
to assembly, installation, distribution, and operation. DfMA falls into the business process 143
stream, while both the manufacturing and the assembly processes serve as focal issues. Since 144
the late 1990s, hundreds of papers have been published on the application of DfX in 145
manufacturing. However, this phenomenon has not happened in the construction industry. This 146
makes it difficult to find all the information needed to apply DfX in the construction industry. 147
148
3.2 DfMA processes and guidelines 149
Researchers such as Swift and Brown (2013), Bogue (2012), and Emmatty and Sarmah (2012) 150
have developed some guidelines for the application of DfMA, as shown in Table 1. It is a 151
systematic procedure that helps companies make the fullest use of manufacturing and assembly 152
processes, e.g., through emphasizing the ease of manufacture and assembly by minimizing the 153
number of parts (Kuo et al., 2001; Eastman, 2012; Bogue, 2012). DfMA aims to determine the 154
cost impact of those materials and processes, and finds the most efficient use of the component 155
design (Ashley, 1995). 156
157
Table 1. A non-exhaustive list of DfMA guidelines 158
Guidelines
Benefits
1
Aim for mistake-proof design
Avoid unnecessary re-work, improve quality, and reduce time and
costs.
2
Design for ease of fabrication
Reduce time and costs by eliminating complex fixtures and tooling.
3
Design for simple part
orientation and handling
Reduce time and costs by avoiding non-value adding manual effort.
4
Design with predetermined
assembly techniques in mind
Reduce time and costs when assembling.
5
5
Consider modular designs
Reduce time and costs due to simplified design and assembly.
6
Consider design for
mechanized or automated
assembly
Improve assembly efficiency, quality and security.
7
Use standard and off-the-shelf
components
Reduce purchasing lead time and costs.
8
Use as similar materials as
possible
Reduce time with fewer manufacture processes and simplified
jointing.
9
Use as environmentally
friendly materials as possible
Reduce harm to the environment.
10
Minimize precast component
types
Reduce time and costs with simplified design, manufacture, and
assembly.
11
Minimize connector types and
quantity
Reduce time and costs with simplified design, manufacture,
assembly, repair and maintenance.
12
Minimize the use of fragile
parts
Reduce costs due to fewer part failures, and easier handling and
assembly.
13
Do not over-specify tolerances
or surface finish
Reduce costs with easier manufacture.
Sources: Swift and Brown (2013); Bogue (2012); and Emmatty and Sarmah (2012) 159
160
However, current DfMA practices in construction still, by and large, follow DfMA 161
guidelines developed in a manufacturing context without sufficiently considering the 162
differences between construction and manufacturing. For example, DfMA procedures in 163
Boothroyd (2005) consider DfA and DfM but not the downstream logistics and supply chain 164
(LSC), which plays a critical role in offsite prefabrication construction. Some construction 165
DfMA guidelines proposed, e.g., Gbadamosi et al., (2019), Kim et al., (2016), and Banks et al. 166
(2018), originate more or less from manufacturing-oriented guidelines. While inspiring, some 167
of these guidelines are not necessarily a good fit with construction’s characteristics, leading to 168
an inability to improve manufacturing and assembly. Some guidelines are proposed in a 169
fragmented fashion without necessarily forming an organic whole, leading to a lack of 170
comprehensiveness, or “easy to use” throughout the building process. The RIBA, in recognizing 171
the potential of DfMA in construction, added an overlay of DfMA to its time-honored Plan of 172
Work. Following RIBA’s vision (2013, p. 24), much “soft-landing” work remains to implement 173
DfMA in construction. 174
175
Connecting general DfMA guidelines (Table 1) with the heterogeneities of the AEC 176
industry to develop DfMA examples could inspire and encourage practitioners. Our stakeholder 177
engagement with the industry has revealed that practitioners including clients, designers, 178
contractors, and suppliers do explore such examples from the perspective of their separate 179
companies. An industry-wide database of DfMA examples could increase its application. 180
Another observation from the literature analysis and industry engagement is that we need to 181
develop DfMA strategies operable in terms of scope, policy, procedure, and so on at company, 182
even industry, level. RIBA’s plan of work and various published DfMA blueprints are certainly 183
meaningful points of departure. To embrace DfMA, individual companies need to work with 184
researchers to devise such operable strategies. Frameworks and guidelines that can link general 185
guidelines with company-specific requirements are highly desired. 186
187
3.3 Cross-sectoral learning 188
When looking at the history of DfMA in construction, scholars often cite the pioneering 189
modernist architect Le Corbusier who, in his influential book Towards a New Architecture 190
(1923), advocated industrialization of construction and proposed the famous maxim, ‘A house 191
is a machine to live in.’ However, the popularity of DfMA in construction is a recent 192