The upsurge of interest in Japanese management practices and their perceived benefits (Pegels, 1984; Voss, 1984; Cusumano, 1988) brought the issue of their implementation at the focal of point of the lean research. The link between implementation and the ability of firms to harness the benefits of manufacturing innovations invented in Japan is straightforward. Knowledge is key to correct implementation so first of all, companies need to be certain of “what exactly” they endeavour to apply (Mehra and Inman, 1992). Wafa and Yasin (1998) acknowledge that unless the implementation of the adopted system is successful the expected benefits will fail to materialise.
Investigating the implementation of JIT in manufacturing operations in the U.S., Mehra and Inman (1992) highlight the limitations of research in this area by recognising that findings are not adequately supported by empirical evidence and as such they are hardly generalisable. Their remarks however, appear to be at odds with recommendations made by Sakakibara et al. (1997) who maintain that despite being limited, the empirical literature can be used to verify the importance of JIT practices. Depending on the adopted research methodology, relevant studies can be broadly classified as conceptual and empirical with the former based purely on secondary research and the latter employing at least one primary research method e.g. questionnaire surveys, interviews, field observations. This distinction is important as different approaches succeed in capturing the perceptions of different circles academic and/or practitioner (Zhu and Meredith, 1995).
Another point of divergence in the available literature concerns the primary research objective of the investigations undertaken. Whilst certain studies propose a complete implementation methodology, framework or model for the adoption of leanness, others place emphasis on the identification of the most significant or widely adopted elements, components, building blocks, tools, techniques, practices and so forth. As a result, the
findings reported in different studies are difficult to compare and generalise (Papadopoulou and Özbayrak, 2005).
Hallihan et al. (1997) observe that lack of consensus in providing universal definitions of systems and their components as well as the absence of standard terminology in the descriptions of features they encompass not only prevent generalisation of the research outcomes but cause great confusion. They proceed to explain that different terms are used to designate the very same feature as frequently as different features are grouped under the same term. Shah and Ward (2007) concur and argue that the semantic confusion surrounding LP results in the same components of LP being masked under different terminology.
The review of the relevant literature suggests that classification is another point in which previous studies fail to converge. Harrison (1992) states that due to their diverse nature, organising techniques encompassed in manufacturing systems into clusters is a complex task. Classification in this context concerns differentiating techniques into core or supporting main or infrastructure (ibid; Flynn et al., 1995). However, there exist studies which simply focus on the identification of critical implementation elements and discuss their prioritisation without separating them into core and peripheral or proposing any form of categorisation (Keller and Kazazi, 1993).
Early literature delving into the implementation of leanness was primarily focused on the TPS. Nevertheless, as interest in the success of the TPS continued to grow, there was a subsequent widening of focus away from the TPS on systems resembling it including JIT manufacturing and LP (McLachlin, 1997). The literature concerned with the implementation of leanness is effectively split into three main strands. The first considers the implementation of the TPS whereas the second and third the implementation of JIT and LP respectively. The most significant volume of research is interestingly covering the second strand.
2.5.1 TPS practices and underpinning philosophy
Mehra and Inman (1992) found that although several studies consider the implementation of leanness within the context of a wider discussion, there is no significant volume of literature specifically addressing this issue. This observation holds true for the early TPS literature. Despite focusing primarily on JIT and the full utilisation of worker capability as the two most distinctive features of the TPS, the seminal work of Sugimori et al. (1977) provides useful guidance on how enabling practices interrelate to support the implementation of the TPS.
Monden (cited in Sakakibara et al., 1997) is credited with the dissemination of key TPS practices in the US through a series of articles focusing on JIT (1981a), the adaptation of the Kanban system (1981b), production smoothing (1981c) and reduction of set-up times (1981d). An integrated approach towards the adoption of the TPS providing an overview of the overall JIT methodology and supporting practices is presented in subsequent publications by Monden (1983, 1998).
The TPS and its overarching layers are discussed in Pegels (1984). Further to describing the operation of JIT and the role of the Kanban information management system, this work provides guidance on a range of shop-floor alterations required to facilitate the smooth operation of the Kanban system and achieve the objectives of JIT production. The overview of Kanban requirements focuses on simultaneous operations (andon yo-i-don), re-designed processes, modified tooling to enable quick machine set- up, multi-task workforce, autonomous inspections and production line warning systems (andon jidoka).
The illuminating review of the full features of the TPS presented by Ohno (1988) provides broad insight into how the system can be adopted. However, what distinguishes this work from the literature concerned with the issue of the TPS implementation is that it places emphasis on the importance of understanding the philosophy behind the innovations developed at Toyota and proposes their holistic adoption as a total production management system.
Spear and Bowen (1999) decode the DNA of the TPS and argue that Toyota’s success lies not in specific practices but in four ground rules implemented in its factories. According to the authors, it is these rules which are observed in Toyota plant visits and hold the key to the implementation of the TPS. The premise of their research centres on Toyota’s commitment to be a learning organisation which employs an almost scientific method to introduce changes. The scientific method is based on hypotheses formulation and experimentations as part of a rigorous and ongoing problem-solving process involving workers and managers at all levels of the organisation. The first three of the proposed rules are design rules determining how the content, sequence, timing of operations can be specified and how the latter can be linked to form a simple and direct product path. The fourth rule describes how workers can be engaged in continuous improvement following the scientific method.
Highlighting the importance of the proposed DNA code in fully understanding and exploiting the potential of the TPS, Towill (2007) develops a triangular prism model to describe the TPS production delivery process. The key elements of the TPS are
organised in four interlinked levels corresponding to vision, principles, toolbox and learning organisation. In line with the prism model, the main TPS principles relate to task interfacing and control which are prerequisites for task coordination and information flow; pathways control is linked to value stream mapping to remove unnecessary pathways and non-value adding steps and improvement programmes. Interestingly, waste elimination features as one of the main tools of the TPS whilst in the early TPS literature (Sugimori et al., 1997, Shingo, 1981; Ohno, 1988) it is regarded as the ultimate objective and goal of the TPS. Practices supporting JIT production including batches of one item and balanced product mixes are also listed as TPS tools. Towill acknowledges that all the tools incorporated in the TPS prism model may be viewed as standard industrial engineering and production management practices. This observation is consistent with Hayes’ (1981) findings according to which Toyota’s success was the result of the emphasis placed by its managers on manufacturing basics and constant improvements of the entire manufacturing process.
The recognition of this fact also lends support to the view that the main point of differentiation of the TPS from conventional manufacturing systems lies in the concept of the learning organisation. The coaching of workers, the function of an internal consultancy and training of suppliers are the key elements listed in the learning organisation level of the model. Apart from being an effective visual tool, the four level prism presented in Figure 2.3 constitutes one of the most contemporary illustrations of the TPS.
Source: Towill (2007)
Figure 2.3 TPS four level prism delivery model
Efficient Production Delivery Process (PDP)
Task Control Pathways Control Task interfacing Improvement mechanisms Standardised activities Reduce waste Batch-of-one
Design for manufacture
Eliminate defects Streamline flows Eliminate delays Balance product mix Learner-leader-Teacher roles
Operations management consultancy Supplier support centre
Vision (Good beliefs) Principles (Operational guidance) Toolbox
(Solving specific problems)
Learning organisation
Inspired by the work of Spear and Bowen, Jayaram et al. (2010) develop a conceptual framework comprising rules and practices which typify the TPS. Their aim is to study the individual as well as synergistic effects of rules and practices on manufacturing performance measured in terms of cost, quality and time criteria. The proposed set of rules sets the context for the implementation of the practices. The rules govern structural work design and seek to promote learning and problem-solving not only within the organisation but externally by involving suppliers. The TPS practices comprise the Kanban system, preventive maintenance, GT, set-up time reduction techniques, in-plant Electronic Data Interchange EDI), shared production schedule information with suppliers and JIT supplier delivery.
Their regression analysis reveals overall positive relationships between TPS rules and practices and manufacturing performance. However, the combined effects of interacting rules and practices on performance create a jumbled picture consistent with the complex nature of the TPS. These findings confirm that some of these synergistic effects may be lost if a piece-meal adoption of TPS practices is attempted instead of an integrated implementation.
2.5.2 JIT production elements and techniques
In contrast to the TPS, the implementation of JIT production is considered as the central or simply a side issue in a plethora of papers. There are two possible reasons for this and it is likely that they are interrelated. Since the introduction of the TPS, its proponents have consistently promoted JIT as the main driving force behind the system. One explanation for the attention drawn to JIT may therefore lie in its widespread recognition as the most dominant concept of the entire system. The second possible explanation may be found in the daunting challenge presented by the sheer magnitude, scope and complexity of the TPS. It is logical to assume that due to the latter researchers took a partial approach when attempting to disentangle its true essence by decomposing the system and focusing on JIT as one of its integral parts. Voss (1984) presents the following list of manufacturing practices which contribute to the success of Japanese firms: clean and orderly workplace; minimised inventory; problem prevention; continuous incremental improvement; incorporating quality in product design and workforce training; equipment policies relating to standardisation and maintenance. These recommendations are based on findings previously reported by Hayes (1981). The use of robots and quality circles are identified as practices of secondary importance. The list further extends to practices reported by other authors
including Kanban, MRP, worker ability to stop the line, attention to detail and strategic operations policy.
Voss’s main objective is to examine the level of adoption of these practices in the United Kingdom (UK) using the cases of one British manufacturing firm and one Japanese owned firm based in the UK as a test-bed. The survey results demonstrate a selective adoption of practices by the British firm. The same empirical results however confirm the widespread adoption of the majority of practices by the Japanese firm with some exceptions concerning the use of robots, quality circles and Kanban. The exclusion of quality circles is not surprising as workforce involvement in quality and continuous improvement is emphasised in other practices incorporated in the list. It is further not surprising to see autonomation excluded as when the concept was originally introduced in the context of JIT it was not associated with the use of robots (Hayes, 1981; Ohno, 1988). Nonetheless, the finding that the Japanese firm had not adopted the Kanban system is intriguing considering its emphasised importance for the operation of JIT production (Sugimori et al., 1997) and the fact that its antidote MRP was not utilised either.
With regards to the adoption of the Kanban system, similar findings are reported by Voss and Robinson (1987) in research employing questionnaires and interviews to establish the level of application of JIT techniques in the UK manufacturing industry. A list of 17 JIT purchasing, manufacturing and supply techniques identified through secondary research was used to collect and analyse the responses of manufacturing companies already implementing or planning to adopt JIT. Flexible workforce, WIP reduction, product simplification, preventive maintenance and statistical process control were ranked as the most frequently implemented or considered for adoption techniques.
Practices including mixed modelling, smoothed line build rate, parallel lines, U-shaped lines recognised by the authors as core JIT techniques were identified in the empirical survey as the least commonly used or considered for adoption with Kanban featuring at the bottom of the ranking table. In line with the authors’ interpretations of the findings, the results revealed a preference towards easier to implement techniques whilst it was noted that elements requiring significant commitment to JIT principles or high investment costs were less favoured.
Harrison (1992) proposes a classification scheme whereby JIT techniques are organised as in-company, inter-company and supportive mechanisms. In-company JIT techniques support the conversion of the manufacturing system into a JIT production
facility and comprise amongst others integrated JIT/MRP, pull scheduling, lot size reduction, layout conversion, total quality and total productive maintenance. JIT deliveries, EDI and long-term contracts are some of the inter-company techniques used to extend JIT to suppliers whereas supporting mechanisms are peripheral systems and procedures e.g. Value Engineering (VE), Statistical Process Control (SPC), undercapacity scheduling used to facilitate the implementation of core techniques. Elements of JIT which are critical to the successful implementation of the system are examined by Mehra and Inman (1992). By reviewing previous literature in which JIT implementation was either the main focus or one of the issues addressed, the authors identify 20 JIT elements which they further group under the following four broad implementation factors: management commitment, JIT production strategy, JIT vendor strategy, JIT education strategy. A questionnaire survey is employed to determine the criticality of each of these factors in the successful implementation of JIT. The statistical analysis of the survey data demonstrates a positive relationship between successful JIT implementation and two factors, namely production strategy and vendor strategy. Specific elements grouped under production strategy include set-up time reduction; in-house lot sizes; GT; cross-training; preventive maintenance whilst vendor lot sizes; sole sourcing; vendor lead time, quality certification of suppliers are JIT elements clustered under vendor strategy. Despite being of certain value, management commitment and education strategy were not verified as critical factors for the successful implementation of JIT.
Keller and Kazazi (1993) regard the creation of a JIT culture and the need for management commitment, workforce involvement and robust relationships with suppliers as the main prerequisites for the effective implementation of JIT. Their broad conceptual research identifies a set of critical JIT implementation techniques which are prioritised in the following order: Total Quality Management (TQM), inventory minimisation, commitment to the principle of getting things right-first-time, maximum flexibility, education and training. Warning lights (andons), autonomation (jidoka), continuous improvement (kaizen) and fool proof devices (poka yoka) are further recognised as important JIT implementation tools.
An auditing procedure designed to assess the speed and effectiveness of JIT implementation is developed by Kazazi (1994). The proposed auditing method is based on a checklist comprising 77 items which are grouped under five areas. 59 items relating to design, implementation and operation of JIT are identified using theoretical and empirical data and grouped under the following four headings: manufacturing technical system requirements, supplier relationships, human resources, quality and
reliability. The remainder 18 items concern performance criteria used to measure the benefits resulting from the successful implementation of JIT. As the main focus of this study is the assessment of JIT effectiveness, the identification of the 59 common JIT implementation practices is a useful by-product of this research.
An investigation specifically focusing on critical elements of JIT implementation is carried out by Zhu and Meredith (1995). The authors acknowledge that previous research attempting to address this issue produced mixed findings and use secondary research data to compile a list of 24 JIT implementation elements which are further ranked in terms of how frequently they are reported in the surveyed literature. Frequency distributions of the data based on research method and author (academic or practitioner) are presented and analysed. Apart from slight variations in the ranking, the same elements dominate consistently the highest ranking positions. More specifically, the ten most frequently reported implementation elements of JIT are: quality circles; set-up time reduction; cross-training; quality certificate of suppliers; GT; in-house lot sizes; vendor lead time; JIT education; relationship with supplier; vendor lot sizes. It is noteworthy that Kanban and other fundamental JIT techniques relating to pull scheduling are not listed among the 24 identified elements. By relying merely on theoretical research, a significant limitation of this study is that it fails to associate the adoption of the identified JIT techniques with specific manufacturing contexts. As a result, direct comparisons of these results with the findings reported in studies considering manufacturing in certain geographical regions are neither straightforward nor safe.
Flynn et al. (1995) posit that TQM practices improve JIT performance by eliminating process variability and rework time whilst JIT practices improve quality performance by exposing problems and providing timely process feedback. Although the main aim of their study is to examine the interaction and trade-offs that exist between TQM and JIT, part of their research is concerned with the synthesis of conceptual data in order to identify practices unique to JIT. The authors claim that the overlapping that exists between TQM and JIT creates great difficulties in accurately associating practices with each specific system.
In the context of their work, practices are the approaches (inputs) used to achieve desirable performance (output). The following elements are proposed as unique JIT practices: Kanban, lot size reduction, set up time reduction and JIT scheduling. Further to a set of unique TQM practices a list of common infrastructure practices which create
the appropriate context for TQM and JIT is also presented comprising among others management support, workforce management and supplier relationship approaches. In a similar study investigating the individual and combined effects of core and infrastructure JIT practices on manufacturing performance, Sakakibara et al. (1997) argue that the crucial role of supportive practices in the successful implementation of JIT is manifested by the high awareness and appreciation of these practices in the early JIT literature. Combining observations from plant visits and secondary research,