State-of-the-art in Lean Design Engineering; a Literature Review on White
Collar Lean
Abstract
Lean is usually understood to be associated with the ‘operations’ of a manufacturing enterprise.
However, there is growing awareness that Lean principles may be readily transferred to the service
sector as well as to knowledge-based activities such as engineering design. To investigate this
possibility, the study described in this paper has systematically reviewed the literature to establish the
state-of-the-art on Lean in new product development. The findings confirm the view that Lean can be
beneficially applied away from the factory; that an understanding and definition of value is key to
success; that a set-based (or Toyota methodology) approach to design is favoured together with the
strong leadership of a Chief Engineer; and that the successful implementation of Lean requires
organisation-wide changes to systems, practices and behaviour. On this basis we feel that this review
paper provides a usefull platform for further research in this topic.
1. Introduction
Lean manufacturing (Womack et al, 1990; Cusumano, 1994; Womack and Jones, 1996; James-
Moore, 1997; Hines, 2004) is emerging as the dominant paradigm for the design of current UK
manufacturing operations. Some see the origins of Lean as a Japanese response to the oil crisis of
1973, examples being Schonberger (1982) who wrote his book ‘Nine Hidden Lessons in Simplicity’
after a study of the Kawasaki production system, and Womack et al (1990) who wrote ‘The Machine
that Changed the World’ following an international study of motor vehicle manufacturing in which the
superiority of the Toyota Production System became clear. Many characteristics of Lean
manufacturing are however, clearly evident in the work of Henry Ford (See: My Life and Work, 1922;
Today and Tomorrow, 1926). At both his Highland Park and River Rouge plants, Ford demonstrated
the essential need to focus on activities that are of service (a value proposition) to the customer and
reduce wastes of materials, time and motion, wherever possible. The value of the Lean paradigm to
the success of manufacturing is without question, whether we base this claim on the success of
‘Fordism’ in the 20
th
century or the Toyota Production System and its derivatives in the 21
st
Century.
Lean is usually understood to be relevant to the ‘operations’ of a manufacturing enterprise, meaning
those processes associated with material supply, component production, and delivery of products and
services to the customer. It is claimed by Womack (1996) and others that ‘Lean thinking’ can be
applied to great effect outside manufacturing operations, although examples of this such as
applications in service-based enterprises are relatively rare. This is not to suggest that there is some
inherent limitation with the Lean paradigm in this context, but it may be that since international
comparisons of manufacturing performance are often easier and waste is more visible in factories,
improved practices are more readily transferred around the world. Clearly, the application of Lean
principles in the service sector represents an opportunity for improvements in competitiveness.
Knowledge-based activities such as design, New Product Introduction (NPI), engineering and Product
Development (PD) are areas within an enterprise where the potential benefits from the adoption of
Lean principles may be significant. To investigate this possibility, the research described in this paper
has been focused on the application of Lean principles to these ‘white collar’ areas that are away from
the factory floor.
The study described in this paper has taken the form of a systematic literature review. The
methodology consisted of identifying relevant databases of publications, searching these using a wide
range of key words and phrases associated with Lean, new product introduction, design, development
and engineering; and then reviewing each article identified. From these reviews it was possible to
compile a set of key findings in which the literature is consistent and also a set of key issues where
questions remain unanswered or where the literature is contradictory. By establishing these findings
and issues, this paper provides a state-of-the-art review of work on this topic and so provides a
platform for more detailed case-based work to improve the understanding of Lean thinking in design-
related activities.
This paper is structured as follows. First, the context of this study is further explained. Then the
research methods are described and the initial results of the search for relevant literature are
summarised. The paper then presents the analysis of the literature and the key findings and issues.
Finally, the results of this analysis are summarised and conclusions drawn.
2. Background: The industrial context
Manufacturing is strategically important to the UK economy. Aerospace, for example, provides
675,000 jobs, £13 billion of exports, and is frequently a leader in the adoption of new technologies and
practices. However, many UK manufacturers face an increasing range of business pressures which
either impact directly on manufacturing operations, such as competition from low cost economies, or
are an indirect consequence of pressures on the whole enterprise. To remain competitive UK
companies are responding in a number of ways. At the level of the enterprise, and consistent with the
Government’s manufacturing strategy (DTI, 2002; DTI, 2004), there is an increasing focus on
innovative, high value and highly skilled activities. This leads to an emphasis on enhancing the design
and development capability within organisations, yet within these non-production functions as with
manufacturing, the pressures from international competition have also increased dramatically in recent
years. Indeed it is argued by Haque (2003) that the continuing existence of a design capability within
the UK requires improvements in effectiveness and efficiency.
There are consequently initiatives to improve enterprise wide productivity in the UK. Increasing
productivity has universal appeal to any western manufacturer faced with increasingly intense global
competition (Lewis, 2000). Within manufacturing operations there continues to be a strong emphasis
on adopting Lean techniques (Womack et al, 1990; Cusumano, 1994; Womack and Jones, 1996;
James-Moore, 1997; Hines, 2004). The synthesis of Lean manufacturing was provided by the
researchers on the International Motor Vehicle Programme of the Massachusetts Institute of
Technology, described by Womack et al (1990) in their book ‘The Machine that Changed the World’.
The term ‘Lean’ was however more widely popularised by the later publication ‘Lean Thinking’
(Womack and Jones, 1996). In this paper, Lean thinking, Lean principles and related concepts will
often be referred to simply as ‘Lean’.
Modern references to Lean have variations in content and perspective. Western companies tend to
focus on Lean through the application of tools and techniques, whereas their Japanese counterparts
talk of philosophy and culture. The philosophical perspective is a multi-dimensional approach
“affecting the entire organisation in every function” (Scaffede, 2002) and encompassing “a wide variety
of management practices, including just-in-time, quality systems, work teams, cellular manufacturing,
supplier management, etc. in an integrated system” (Shah and Ward 2003). Whatever the
perspective, the elimination of waste is the principle that has traditionally been at the heart of the Lean
approach (Ohno 1988, Womack and Jones 1990, Papadopoulou et al 2005). Ohno (1988) identified
seven forms of waste although in practice, the most frequently cited of these is excess inventory. Lean
manufacture discourages holding excessive levels of inventory as this is felt to be a wasteful and
expensive response to operational problems that has the effect of hiding the real causes of these
problems. Reducing inventory is recommended as this will expose the problems and forcing the
underlying causes to be addressed (Bodek 2002).
The case for Lean is usually made by considering the remarkable commercial performance of Toyota
whose profits at the end of 2003 were $8.3 billion. This was greater than the combined profit of GM,
Chrysler and Ford, and for the first time ever Toyota became one of the top three car sellers in the US
(Liker, 2004). In 2006 Toyota is likely to reach the number 1 position. Similarly Womack et al (2001)
provide evidence of benefits of Lean achieved in a number of companies across the world that operate
in very different market sectors from Toyota, such as Porsche and Pratt and Whitney. However,
achieving such improvements is often difficult (Scaffede, 2002) and there is clear evidence in the
literature that the benefits of Lean can not be realised simply by adopting a few tools and techniques.
In the case of Toyota, Cleveland (2006) notes that the Toyota Product Development System has been
key to their success and claims that Toyota’s Lean manufacturing system is actually an extension of
their product development philosophy and not the reverse. Conversely, most Western manufacturers
are focusing their Lean initiatives at operations with (as this paper will demonstrate) few attempts to
adopt Lean in design-related activities.
Following the example of Toyota, there appears to be a significant opportunity to benefit from the
adoption of Lean in product design, engineering and development. Indeed, there may actually be few
practical alternatives and the potential benefits of Lean in design-related activities are certainly worthy
of careful exploration. Therefore, the purpose of this paper is to provide an up-to-date review of Lean
(in its widest interpretation) and its application to the processes of Product Development (PD) within
manufacturing enterprises.
3. Research Programme
3.1 Aim, scope and research questions
The aim of the research presented in this paper was to seek detailed descriptions of the application of
Lean principles to product design, engineering and development. To achieve this, this study has
carried out a systematic review of literature in this field. The scope was limited to publications dealing
with the processes associated with Product Development (PD). This means that studies of the
application of Lean to other types of ‘white collar’ work, such as sales order processing for example,
have not been included. Similarly only descriptive articles reporting on real examples and cases have
been considered so that purely theoretical, conceptual and abstract works have been excluded. An
example of a publication that is clearly within the scope of this review process is that of McManus
(2005) in which the author reviews the result of applying Lean engineering techniques to existing
aerospace programmes.
Our initial approach to this study has been to consider the questions that a typical practitioner might
pose when considering the application of Lean to product design, engineering and development.
These were considered to be:
•
What is commonly meant by the term Lean?
• How is Lean commonly applied?
• Are there any apparent limitations to the application?
• Where are the best examples of good practice?
The purpose of these questions was to guide the search although the authors were mindful that the
literature may not be sufficiently developed to allow all these questions be addressed with full rigour.
Hence, it was not expected that each should necessarily lead to a key finding.
3.2 Search strategy
The search strategy was developed by first identifying the relevant data sources, time frame and key
words. Initially a very broad selection of databases was identified covering journals, conference
proceedings, books, and articles from trade journals. These included Compendex, Inspec and
Emerald, along with the more traditional library cataloguing systems. These databases provide access
to a wide variety of publications such as the Journal of Engineering Design, International Journal of
Automotive Technology, Software and Quality Journal, Journal of Product Innovation, Journal of
Construction Engineering and Management, Proceedings of the Institute of Mechanical Engineers,
Engineering Technology and Systems Engineering.
In order to restrict the search to more recent publications, the time frame for this study was initially
chosen to include only literature published between 1999 and 2005. However, as the research
progressed this was extended, firstly by widening the search criteria to include publications before
1999 and secondly by checking relevant publications cited in the literature that had already been
identified by the original search.
The search strategy used a range of keyword combinations including Lean, product, case study,
engineering, Toyota, NPI, development, introduction and aerospace. Wildcard keywords such as
coordin* were also used, this particular keyword being intended to capture papers discussing how
organisations coordinate resources and undertake cross-functional activities. Thirteen search strings
featuring different combinations of key words were used. There are several interpretations of the term
‘Lean’ and the one that was used here is that chosen by Hines et al (2004). This means that papers
dealing with just-in-time, waste reduction or value adding have all been included in this review.
Furthermore, as alluded to above, ‘white collar’ activities or functions that have been considered are
those that may have some association with PD such as design, research and development, marketing,
sales, production engineering and supply chain management.
The lists of hits for each search string were firstly edited to remove any duplicate records that
appeared. The titles were then checked to ensure relevance to the review. Abstracts of all other
articles and papers were then reviewed before selecting publications for a full review. During this
exercise no restriction was placed on the form of publication so, for example, a series of books with
‘Lean’, ‘product development’ and ‘new product introduction’ in the title were acquired and considered
for further review. Similarly, Internet searches using title/author/keyword combinations also proved
useful.
3.3 Results and analysis
The search strategy initially identified many relevant publications. Table 1 shows the number of
journal articles and conference papers associated with each search string used. In most cases the
number of journal articles exceeded that of conference papers. This might be explained by the
databases indexing the journals more comprehensively. Many of the 550 publications that were
retrieved against the search string ‘Lean+product+development’ were also retrieved against the other
search strings such as ’Lean+product+design’ (370 hits) and ’Lean+product+engineering’ (845 hits).
The large hits score for this last combination reflected the abundance of publications on the
operational aspects of Lean manufacturing as well as papers dealing with product engineering for
Lean manufacturing. Perhaps surprisingly the search string ’Lean+npi+aerospace’ found just 3
publications. Search strings combining ‘Toyota’ or ‘case study’ with ‘Lean+design’ or
‘Lean+development’ resulted in results more in line with expectations and gave 139 in total.
Following a review of the publications that were retrieved, it was established that at the time of the
search there were 24 articles available that are suitable for review as part of this research and that all
were published within the chosen timeframe of 1999-2005. These are shown in tables 2 and 3 by
author, title and source, in chronological order. Our analysis was then conducted on these particular
articles.
Having identified the literature, the first pass of the review process involved briefly summarising each
publication against the initial research questions. This enabled a better understanding of the topics
covered by these papers and some understanding of the emergent themes. Each of the 24
publications was then read in detail by the researchers and mind mapping techniques were used to
capture and represent the consistent messages. These were then distilled into the key findings (topics
on which the views of the authors converged) and issues (topics on which authors had differing
views). Finally, the results were presented to practitioners to test the readers’ interpretations of
publications and check that the terminology was precise. On the basis of this analysis, the following
key findings were developed.
4. Generation of key findings and issues
The literature review process allowed six key findings and three principal issues to be established.
This section presents each in turn.
4.1 The definition of Lean is drifting
In the 1980s Lean was associated with a reduction in waste in the factory, then on quality, cost and
delivery during the 1990s before the focus shifted to customer value after 2000 (Hines et al, 2004).
Today, the emphasis ‘value’ and how it can be maximised, is growing in popularity. The shift from
waste elimination to value enhancement is exemplified by Browning (2000) who argued that during the
PD process maximising value can be achieved by doing more not less. Haque (2004) also argued that
engineers need to move from a production focus in which the primary aim is waste reduction to one of
identifying and enhancing value. Activities that create useful additional information and/or reduce risk
are examples of this. The consequence of this drift is that there is a danger for both researchers and
practitioners, of misinterpreting the ideas that are being put forward during any discussion about Lean.
It is also important to distinguish between the philosophy, principles, techniques, and values
associated with Lean. Again, conversations are frequently held at varying levels, and this leads to our
first finding.
Finding 1: The definition of Lean is drifting. Whilst earlier papers saw a Lean as a philosophy
for waste reduction the emerging view is now one of value creation.
4.2 Lean is applicable to PD processes
There is a wide variety of examples where Lean has been applied in this context with publications in
such fields as software (eg: Middleton, 2001 and Poppendieck, 2005); construction (eg: Javier, 2002)
and aerospace (eg: Haque, 2004 and McManus, 2005).
In software the consideration of the waste principle (Poppendieck, 2005) addresses the shortening of
long information feedback loops, the existence of which is cited as the reason why over 50% of all
newly developed software is seldom, if ever, reused. The result of shortening feedback loops creates
flow, increases speed and quality and hence reduces cost and adds value. Middleton (2001), whilst
showing how the concepts of Lean manufacturing could be successfully transferred to software
development, noted that the major implementation issue was the requirement for deep changes in the
way organisations are managed. In his case work Middleton documented an account of the full
adoption of Lean by a software development company and concluded that the extensive Lean
manufacturing literature is a valuable source of new ideas for software engineering.
Javier (2002) describes the application of the Lean principle of waste elimination in the design process
of the construction industry. The design process is conceptualised as a flow of information, which
lends itself to waste reduction through minimising the amount of time before information is used. Value
generation arises from capturing the customer’s requirements and transmitting these accurately in the
overall design process.
Haque (2003) reported that the application of Lean to engineering processes in the UK aerospace
industry has been lacking, although case studies indicated that the application of Lean to PD was
feasible and capable of delivering benefits for large and small companies. In his later work he noted
the analogy between the roles of information in the PD value stream and material in manufacturing.
This explains his recommendation that engineers focus on the identification and enhancement of
value. Similarly McManus (2005) reported that in the US aerospace industry the application of Lean
design techniques was underway, but that techniques were not well established, and many
practitioners were feeling their way forward.
Finding 2: It is clear that Lean can be applied (although the extent is yet to be confirmed) to
product design, engineering and development in the aerospace and other sectors.