For Peer Review

Adaptation of the Value Stream Mapping approach to the

design of lean engineer-to-order production systems: a case study

Journal: Journal of Manufacturing Technology Management

Manuscript ID: JMTM-May-2012-0054.R3

Manuscript Type: Article

Keywords: Case studies, Production systems, Value stream mapping, engineer-to-

order

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Adaptation of the Value Stream Mapping approach to

the design of lean engineer-to-order production

systems: a case study

1. Introduction

Small and medium-sized enterprises (SME) are numerous and represent the backbone of

the European economy (Müller et al., 2007). Due to their flexibility, the entrepreneurial

spirit and the innovation capabilities SME have proven to make an important

contribution to the economic stability and sustainability of a country. However, to

compete in an increasingly competitive global marketplace, SME have to strive for

world class performance through a consequent implementation of lean principles.

In literature mainly examples for the implementation of Lean principles in large

enterprises can be found but there is still less documented evidence of its

implementation in smaller organizations (Achanga et al., 2006). Furthermore, the Lean

Manufacturing concept is well described in the literature in the context of low-mix high-

volume production, and recently also some research has been done in a high-mix small-

lot size environment (Horbal et al., 2008). However, in small and medium sized

enterprises, especially in those working in the field of construction or construction

supply where the customer order usually determines and triggers the design and

consequently the production, Lean tools and methods known from repetitive production

usually do not fit (Romero and Chávez, 2011). They require different manufacturing

approaches and optimization methods for so called project manufacturing or engineer-

to-order (ETO) manufacturing (Yang, 2013). Major problems can be detected with the

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proper design of one-piece-flow production cells and material flow based on pull

system. However, recent studies show that there are some Lean concepts that can be

broadly applied in most industrial environments, such as “elimination of waste” and

“just in time deliveries” (Gulshan Chauhan and Singh, 2012; Yang, 2013). The purpose

of the paper is to present a case study of implementing Lean concept in a craft-

production oriented small enterprise and to derive from the findings some useful

insights for the adaptation of the Value Stream Mapping approach to the design of lean

engineer-to-order production systems.

2. Literature review

In the past decades a large variety of methods and tools has been developed and used to

design, optimize or evaluate productive systems, helping to improve and to accelerate

the design of lean and agile materials and information flows in manufacturing. Several

researchers (Braglia et al., 2006; Serrano Lasa et al., 2008) reviewed different tools and

methods for the redesign and improvement of production systems. They came to the

conclusion that these “do not cover the same framework as VSM, neither the same

objectives nor the same level or degree of completion of manufacturing systems design”

(Serrano Lasa et al., 2008, p. 42). Among these methods, the most important ones are

flow diagram charts, Icam DEFinition for Function Modeling (IDEF0) and the

complementary Integrated DEFinition for Process Description Capture Method

(IDEF3), Graph with Results and Actions Interrelated (GRAI), and various tools for

material and information flow modeling.

Flow diagram charts represent a hierarchical business system modeling technique

widely used in 90s’ business process reengineering currents. They were mostly

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designed for business processes and thus did not really adapted to manufacturing

process modeling and redesign. IDEF0 is based on the established graphic modeling

language Structured Analysis and Design Technique (SADT) and is oriented towards

hierarchical manufacturing system function modeling, while IDEF3 is a complimentary

technique for producing a dynamic model of the system (Kim et al., 2003, Aguilar-

Saven, 2004). The GRAI method is a decisional modeling technique and is based on

hierarchical production planning (Rahmouni and Lakhoua 2011). The above mentioned

methods tools are purely qualitative, in addition, GRAI does not even consider material

and information flows (Serrano Lasa et al., 2008). In more recent years, different tools

for material and information flow modeling in manufacturing have been introduced that

cover the lack of quantitative aspects in modeling. However, due to their quantitative

character these tools require significant efforts in terms of education and time and thus

are not that frequently used for optimization of manufacturing systems.

In recent years, many publications have extensively documented the implementation of

value stream mapping as a key method to implementing Lean concepts, in various

manufacturing sectors. Value stream mapping (VSM) is a conceptual framework

popularized in many western industrial companies since the publication of the book

“Learning to See – Value-stream mapping to create value and eliminate muda” (Rother

and Shook, 1998) started diffusion of the practice-oriented mapping and optimization

method developed on the basis of a broad empirical industrial evidence.

A value stream can be defined as a sequence of activities required to design and

manufacture/provide a product or service (Erlach, 2010). Value stream mapping

represents a very effective method for the visualization, the analysis and the redesign of

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production and supply chain processes including material flow as well as information

flow (Rother and Shook, 1998; Womack et al. 2002; Matt, 2008). It is used primarily to

identify, demonstrate and eliminate/reduce waste (Seth et al., 2008), as well as to create

continuous flow in manufacturing processes (Marchwinski and Shook, 2003; Hines et

al., 2004). First implemented by automotive industry with a strong focus on low-mix

series production (Schweizer, 2011; Anand and Kodali, 2009; Seth and Gupta, 2005),

value stream mapping was stepwise expanded to various applications (Tapping and

Shuker, 2002; Jones and Womack, 2003) and to other industries (Fontanini and Picchi,

2004; Braglia et al., 2006; Singh et al., 2006; Horbal et al., 2008; Seth et al., 2008;

Taylor, 2009; Singh and Sharma, 2009; Vinodh et al., 2010; Marudhamuthu et. al.,

2011; Chowdary and George, 2012) and was enriched by additional tools and

techniques (Singh et al., 2006; Gurumurthy and Kodali, 2011), especially with

simulation (Lian and Van Landeghem, 2002), for example by the application of QUEST

simulation software for developing the simulation models for current and future state

maps (Anand and Kodali, 2009) which is particularly helpful to quantify possible

effects of process changes in advance and to evaluate improvement alternatives without

disrupting actual production (Parthanadee and Buddhakulsomsiri, 2012).

Braglia et. al. (2006) showed that VSM cannot be used directly for very complex

manufacturing processes with merging flows. Thus, the research team defined a

procedural approach: first the part families are identified, and then the machine sharing

among the targeted families is determined identifying and optimizing the critical value

stream. A key issue in all research activities involving VSM technique in a

manufacturing environment is that suitable part or product families can be identified.

However, in an engineer-to-order (ETO) environment as it can be typically found for

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example in construction industry (Forsman et al., 2011) the tools and methods known

from repetitive production usually do not fit or have to be limited in use for lean

improvements in simple processes (Al-Sudairi, 2007). Another shortcoming of applying

the traditional VSM approach in an ETO environment is that it fails to map multiple

products with different routings and that it lacks suitable economic measures for value

or other typical manufacturing performance parameters (Stamm and Neitzert, 2008;

Braglia et al., 2006). Moreover, the original VSM tool lacks the spatial structure of the

facility layout, and the related impact regarding interoperation material handling delays

(Romero and Chávez, 2011), which, however, is a very typical issue in the large and

heavy good ETO manufacturing. In the context of construction industry, some

researchers report about value stream macro-mapping (VSMM) or value network

mapping (VNM) approaches (Khaswala and Irani, 2001; Arbulu et al., 2003; Fontanini

and Picchi, 2004), especially focusing on the supply chain of a specific engineer-to-

order processes of construction industry. The VSMM approaches focus only on the

optimization of the supply chain steps but do not consider the specific issues of an ETO

manufacturing environment (Dessens and López, 2012). VNM is able to map the

complete network of overlapping flows in a value chain; however, no recommendations

regarding improvements and future state map development are available (Romero and

Chávez, 2011).Thus, a large number of small and medium sized companies which are

mainly focusing their activities on craft-production still cannot fully take advantage of

the efficiency gains that can be obtained by VSM/VNM guided lean implementation.

3. Research objectives and methodology

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The main research question of this paper is: to what extent can the approach of value

stream mapping and optimization be adapted to the specific requirements of an ETO

manufacturing system in SME in order to improve its overall efficiency in terms of

time, quality and costs?

The research question is addressed by discussing the real industrial case of a greenfield

production facility project. According to several authors, case research is most suitable

for the development, testing, disproof and/or refining of a theory or hypothesis

(Woodside and Wilson, 2003; Gummesson, 2005; Vissak, 2010) as well as for the

determination of further research needs (Halinen and Törnroos, 2005; Siggelkow,

2007), especially in a complex and dynamic context (Perren and Ram, 2004). Especially

in the field of VSM single case study based research is frequently applied, so far mostly

in the field of series or mass production: Lian an Van Landeghem (2002) used the case

of mythical train manufacturer, many other authors refer to automotive or automotive

supplier cases (Rahani and Muhammad al-Ashraf, 2012; Schweizer, 2011; Anand and

Kodali, 2009; Seth and Gupta, 2005), appliance manufacturing (Abdulmaleka and

Rajgopal, 2007), to domestic appliance and consumer electronics industries (Serrano

Lasa, 2008) or also to batch production in the roasted and ground coffee industry

(Parthanadee and Buddhakulsomsiri, 2012). The single case study research approach

has proven to be very suitable for studying the effects and usefulness of VSM

application in different industry environments (Chen et al., 2010; Nepal et al., 2011;

Chiarini, 2012; Chowdary and George, 2012), to derive conceptual hypotheses and to

identify further research needs and has therefore been chosen to investigate the

suitability of VSM in an ETO environment and to identify eventual research needs for

adaptation. The case research was performed by using the following main sources of

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information, before project start, during the project and after the project completion: (1)

observations on the shop-floor, (2) a detailed process analysis, and (3) interviews and

informal discussions with the company’s project team consisting of experienced

managers, planners and foremen.

4. Case study

The chosen company is a medium sized Italian engineer-to-order producer of large and

heavy steel constructions, such as steel structures and facades for civil and industrial

architecture, with a yearly turnover of 48 million Euro and about 150 employees. Every

product is unique – consequently, engineering design and production is made to the

specific customer order (batch-of-one production). Even if the final product can involve

some common materials or standard parts, every customer order requires individual

bills of materials and production routings to complete the final product within an agreed

deadline. Demand is irregular. The process typically consists of cutting, machining,

assembly (tack welding), welding (seam welding), and coating.

The company started as a very small craft business and established its niche strategy

from the very beginning focusing on the implementation of technically demanding

individual solutions. The steel constructions realized by the company are true

masterpieces of architecture and engineering and often are designed to become icons of

their locations. Carried by the good reputation in the world of architects, the company

was able to realize an average growth rate of nearly 10% per year during the last ten

years. As a result of continuous growth soon the available space in the existing

production facilities at the old site was no longer sufficient. As a further extension of

the old structure was not possible, the management decided to plan a new production

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plant on a Greenfield site. At the same time, the chance of planning a completely new

production system should be used in order to redesign production processes and layouts.

During the last ten years of steady growth production management had paid more

attention to the timely order fulfilment and neglected the necessary organizational and

structural improvements in manufacturing. The organization was not prepared for these

growth rates and the growing market pressure finally led to a decline of order and

cleanliness, and subsequently to productivity losses and serious quality problems.

Instead of treating the problem at its root and initiate necessary changes in production

processes and organization, more often partial orders were outsourced to third parties

that in turn led to a decline in overall profitability. Production management therefore

took the upcoming redesign of the plant site as an opportunity to reshape the production

processes, structures and organization of according to Lean principles in order to

improve its competitiveness in terms of productivity, times and quality. Traditionally,

Lean focuses on high volume repetitive manufacturing industries like automotive and

consumer electronics. However, the usefulness of implementing Lean concepts in an

ETO environment is also confirmed by recent literature: Yang (2013) formulates several

research hypotheses on the basis of a literature research which investigates key

practices, manufacturing capability and attainment of manufacturing goals from the

perspective of project/engineer-to-order manufacturing, highlighting for example “just

in time (JIT)” and “total quality management (TQM)” as useful Lean concepts that can

be applied to ETO industry. This finding is confirmed also by the research results

presented by Gulshan Chauhan and Singh (2012).

A project was defined with the following twelve steps:

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1. site selection

2. current state analysis of existing manufacturing processes

3. future state mapping of manufacturing processes and optimization of material

flows and layouts

4. planning of new manufacturing (layout) at the new location

5. architectural planning

6. request for construction permit

7. investment planning and cost estimates, financing plan

8. static construction planning

9. scheduling for construction execution

10. invitations to tender (building and equipment)

11. construction execution

12. official inspection and approval

The following considerations mainly refer to the steps 2 and 3.

4.1 Current state analysis of existing manufacturing processes

The current state analysis was performed in the old production plant. As mapping

method, the VSM approach was chosen. In contrast to the usual value stream analysis,

no selection of product families was made because this step is not applicable in an ETO

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environment. Instead, two types of typical projects were classified: (1) major steel

structures for civil or industrial buildings (e.g. industrial buildings, bridges, sports

centres, ski jumps etc.), and (2) smaller steel constructions (e.g. steel stairs, railings

etc.). In this section, only the mapping of (1) will be explained in more detail.

First, the current state of the major steel structures value stream was mapped. In contrast

to the recommendations of Rother and Shook (1998) the current value stream was not

recorded while walking along the actual pathways of material and information flow.

Since no product families are recognizable in the strict sense a different approach was

selected: in a workshop with key representatives of the production management the

current value stream was outlined on a brown paper sheet using, however, the same set

of symbols or icons as for usual mapping tasks (Figure 1).

Figure 1: The current state map as a superposition of n value streams.

Based on the experience of the workshop participants the full range of possible paths

was recorded which material flow passes through depending on project type and

required processing: thus, the current state map does not display one single value stream

but the superposition of n value streams. For an ETO manufacturer, a product is the

final result of a project and thus meets the definition of being temporary and unique: it

usually has unique customer designed elements and the inventory levels are low (Yang,

2013). Although the products are manufactured in environments similar to

manufacturing job-shop conditions, the value stream mapping requires a different

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approach. Due to the uniqueness of the single products/projects quantification in terms

of buffers/lead times and cycle times is not feasible. Thus, this information is not added

to the value stream maps similar to the previously outlined value network mapping

approach.

The following weaknesses in the production and information processes were identified;

the five main weak points are highlighted in lightening bursts (see Figure 1):

1. The production often gets the needed drawings late or drawings are not yet

defined when production is supposed to start; according to two years of data

recording this problem happens in about 25% of the cases. This leads to

rejection and increased coordination effort between production and technical

department. The resulting additional times in production and technical

department were roughly estimated at about 5-10% by the responsible managers.

2. The shipping list is often not available or arrives too late. This leads to problems

in order picking.

3. There is a lack of coordination to bring together the materials for assembly. The

single parts are independently produced and delivered to assembly.

4. The capacity balance between tack welding and seam welding is not sufficiently

flexible. The consequence is a high incidence of uncontrolled buffer stocks. This

can only measured indirectly by an evaluation of the occupied spaces; according

to management estimations, space requirements in this area could be reduced by

about 50% with a better capacity balancing between the two areas.

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5. Lack of overview in the shipping area lead to faulty deliveries to the

construction site. This must be compensated with additional rework and

transports. In almost 10% of cases there are additional deliveries due to missing

parts.

On this basis, ideas for improvement and future state mapping could be developed.

4.2 3. Future state mapping of manufacturing processes and optimization of

material flows and layouts

Rother and Shook (1998) presented a set of guidelines helping to develop a lean value

stream. However, these recommendations are mainly based on best practice obtained in

series or mass production. In an ETO environment, every product is usually “a project”

and is therefore unique. At first sight, a strict orientation at continuous flow does not

seem an appropriate approach. On closer examination, however, some approaches for

achieving a continuous flow can be used quite productively.

ETO extends the make-to-order (MTO) strategy by a stage in which a product is

designed to order according to individual customer needs. The logics and sequence of

the main processes in the ETO model is very similar to the MTO case; however, the

products tend to be highly influenced by the interaction with customers even after

production order release and start of production (Meredith and Akinc, 2007).

To develop systematically a future state map, the guidelines proposed by Rother and

Shook (1998, pp. 40-50) were analyzed during the case research regarding their

usability for an ETO environment and changed or adapted accordingly. On this basis, a

set of guidelines for ETO value stream optimization could be developed.

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Guideline #1: Identify merge-points in the current state map and introduce

synchronization-areas in front of them

This guideline is based on guideline #3 proposed by Rother and Shook (1998) and

adapts it to specific ETO requirements. Merge-points can be defined as those points

where two or more components or modules are simultaneously needed to perform a next

production activity, e.g. assembly (Stamm and Neitzert, 2008). In the original sense, a

lean supermarket is an area between processes that cannot be synchronized to a

continuous flow, where a standard amount of stock is kept in order to supply a

downstream process without interruption; synchronization between two processes with

different cycle times is realized by introducing a pull-principle (e.g. Kanban). However,

as there are nearly no standard components in a pure engineer-to-order production it is

difficult to implement pull principles between production stages. In this context,

supermarkets need a different alignment: they serve as synchronization and picking

zone in front of a merge-activity. This requires a planning of the upstream

manufacturing steps such that the components that have to be synchronized arrive in the

supermarket at the same time or with a minimum time lag. This aspect will be discussed

in guideline #3.

Guideline #2: Combine machining processes with strongly fluctuating workload in one

workshop area operated by a highly flexible workforce

Since the workload of the various machining processes (grinding, drilling etc.) is

subject to very strong fluctuations due to the unpredictable mix and sequence of

different products/projects, they were combined into one shop called "machining"

(Figure 2).

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Figure 2: The future state map.

Workforce was trained to be able to operate all machines within this zone so that due to

a flexible shifting of personnel it is now possible to rapidly react to fluctuations in

workload. Production planning and control department early detects extreme load peaks

that exceed even the improved capacity flexibility and outsources these processing

volumes to external suppliers.

Guideline #3: Split customer orders into suitable production orders, and release equal

time increments of work

ETO producers usually release work by customer order. This has several disadvantages:

large projects especially in construction are usually subject to changes from architects or

clients often long after the production has already started. This leads to the following

dilemma: Expecting changes from the customers, the technical department holds back

the production release as long as possible even risking a non-compliance of the delivery

date. The production management on the other hand tries to anticipate as much work as

to optimally balance the manufacturing capacities. To solve this problem, first the

customer order must be split into several production orders that are released according

to the progress on the construction site (Figure 3).

Figure 3: Hierarchical splitting of documents for production.

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A single production order might contain different components or modules each

following one of n possible different value streams (Figure 3). In this context, a value

stream may be defined as one of n possible pathways through the production system’s

manufacturing steps or stations. For every value stream a unit of work based on a time

increment or “pitch” (Rother and Shook, 1998, p. 47) can be defined. In contrast to the

traditional definition of a pitch as a standard time increment, in ETO production it has

turned out to be more practical to define an upper limit for the time increment. Its

maximum length usually is determined by the single value stream’s bottleneck process.

In total, 4 different base types of value streams and their related pitches could be

identified:

− VSM-1: metal sheet cutting – machining (pitch < 1 hr)

− VSM-2: plasma cutting – machining (pitch < 4 hr)

− VSM-3: sawing – machining (pitch < 1 hr)

− VSM-4: sawing (pitch < 1 hr)

Introducing this scheduling mechanism, production can be flexibly scheduled according

to the highest priority regarding the production orders shipping schedule, and at the

same time the material flow becomes much more continuous.

Guideline #4: Avoid crossings of material flows

In a workshop oriented batch-of-one production, typically material flows tend to cross

due to numerous possibilities of processing sequence combinations. Especially in an

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environment of large and heavy goods production, crossings of material flows create a

lot of non-value-added activities, also often referred to as “muda” or “waste” in the

context of Lean Manufacturing, such as excessive material handling and material

buffers; interviews with material handlers showed, that 10-20% of their time is wasted

with unnecessary material handling caused by bad accessibility of parts in buffer stocks.

Moreover, problems with occupational safety and unnecessary waiting times were

shown in high traffic flow of material intersections. As overlapping of different value

streams may not be completely avoided, it makes sense to reduce the crossings

wherever possible. However, as demand varies widely and data are not enough reliable

for doing a material flow optimization with a traditional transport matrix (Schenk et al.,

2010). In the practical application, the following approach for the use of the transport

matrix has proved to be suitable. The data fields eij in the from-to-matrix contain the

transport intensity information about the relationship between the source Qi and the sink

Zj (Schenk et al., 2010). Transport intensity may be defined as follows:

transportation intensity = transportation frequency x transportation unit

Both transportation frequency and unit cannot be clearly defined due to the huge variety

of different products/projects in a batch-of-one steel construction environment. Thus, an

evaluation based on experience of workforce and production management can be

applied. During a workshop with production personnel, for every eij the transport

intensity is calculated assigning to transport frequency a value in the range from 1 to 3

(1 = low, 2 = medium, 3 = high frequency). The same is done for the transport unit,

assigning a value of 1 to easy-to-carry items that can be transported by every worker, a

value of 2 for components or subassemblies that need to be carried by a forklift truck

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and a value of 3 to heavy steel constructions that need to be handled with an indoor

crane. The multiplication of the two parameters opens a series of values ranging from 1

(very low transport intensity) to 9 (very high transport intensity). For example, there is a

high transport frequency (value = 3) between the plasma cutting station and the grinding

machine; these parts are usually transported by forklift truck (value = 2). From this we

calculate a transport intensity between plasma cutting and grinding of 3 · 2 = 6. This

calculation is done for all data fields eij in the from-to-matrix. Then, the individual

transport relations are sorted in descending order according to their value. The resulting

range can be split in three clusters: stations with transport intensity values of 7-9 have to

be disposed in close proximity to each other, 4-6 are arranged around the core section in

a suitable way, and 1-3 do not need special attention and can be located where it is most

opportune. In a later layout design, this information is extremely useful in order to

select the right location for the single work stations and machines.

Guideline #5: Flexibly assign assembly spaces in accordance with production progress,

priorities and space requirements.

As the modules for each production order differ much in space requirement and priority,

they must be flexibly assigned to varying places in the assembly shop. This can be done

with a space pattern table. This space pattern table simply subdivides the available

assembly area in suitable rectangles Rij, similar to a chessboard. In this industrial case, a

total of 16 rectangles with uniform dimensions of 7m x 14m were chosen, from R11 =

“A1” to R44 = “C4”. These are distributed over a 28m x 56m section of the production

hall. However, this choice depends on the product related assemblies/subassemblies and

their average space requirements and therefore cannot be generalized. When a

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production order is released from the picking zone to assembly, number ≥ 1 of these

rectangles (in case they are more they clearly should be located near to each other) is

assigned to this production order. The commissioned material is transported together

with the accompanying documents to the designated assembly area and handed over to a

“mobile” assembly work group which migrates with the assigned production orders

from one assembly space to the next. This mobile assembly group accomplishes both

tack and seam welding in the defined assembly space; this way the capacity between

tack welding and seam welding is balanced and uncontrolled buffer stocks in assembly

can be avoided. The completed production order is then forwarded to the next station

which is coating or shipping.

Guideline #6: Avoid the storage of residual material near the machines and workplaces.

In a project driven batch-of-one production a habit originating from craft production is

widespread, i.e. to keep the residual material in small buffer stocks nearby the machines

or workplaces, often even for long periods. Although a survey of several companies in

the steel and facade construction has shown that many materials can be used only once

as they are ordered specifically for one project, also these materials are usually kept in

storage. But even if the residual materials can be reused at a later point in time, it is

important to keep them ordered in a central warehouse. This has various advantages.

Firstly, the cost of the often lengthy search is reduced. In addition, the space around the

machine remains free and clean which reduces the handling effort and the risk of injury.

It may be argued that this increases the cost of internal transportation. However, with an

order-related picking of material and components in a central warehouse, these parts are

transported together with other materials and hardly increase internal transportation.

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Moreover, by eliminating unnecessary searching at the single workstations much

productive time can be saved.

The six guidelines are the result of intense work and discussion process with the VSM-

working group of the company. As a result, a future state map (Figure 2) was developed

and implemented as part of the design of the new factory site. VSM offered a good basis

to raise awareness about muda within the project team and led to a series of

improvement measures which have been incorporated into the new plant layout and

process design. Of course there are difficulties to quantify the effectiveness of these

measures in a typical batch-of-one ETO environment. However, the company has been

working with the new processes and within the new layout structures now already for a

sufficiently long time to draw first conclusions, and the efficiency and quality of work

could be improved significantly. Overall, since the implementation of the above

described changes in the new factory site the actual measured output rate (in turnover) -

adjusted for outsourcing, price increases and inflation - grew by 20% without necessity

for more workforces.

Conclusions and further research work

An engineer-to-order (ETO) system typically deals with projects: every product is

unique and is designed and produced according to a customer order. Customer

requirements and shipment dates vary from product to product. Consequently, there is

no inventory in terms of finished products, and also raw material is usually purchased

project-oriented. Furthermore, sequences and cycle times of the manufacturing

processes vary widely and do not allow a proper balance of the workflow through the

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production. Review of VSM related literature revealed that due to the differences of an

ETO environment to series or mass-production the conventional VSM approach needs

to be adapted. The conventional VSM approach is designed for high volume repetitive

manufacturing industries; in a batch-of-one environment it can be applied only project

by project. Against the background of the missing support of meaningful data and

information due to the project-related variations in times, workload and inventory level,

different approaches and guidelines are needed for the optimization process between

current and future state mapping.

In this paper, an adapted value stream mapping approach for an engineer-to-order

environment has been presented and discussed on the basis of the practical insights

obtained during an industrial case research. The case research revealed that although an

ETO manufacturer typically deals with projects and every project is unique, the

mapping and the analysis of the superposition of multiple overlapping value streams

shows general opportunities for improvement. These opportunities were generalized in

6 guidelines for the future state mapping which offer a good basis to start discussion and

to raise awareness about waste within the manufacturing teams. The results obtained are

limited but could be very useful to industry as they produced a set of guidelines for the

optimization or re-design of a value stream in a batch-of-one environment. Despite the

focused nature of a case research and the associated limitations of the findings, the

obtained results encourage assuming the transferability to similar problems. However,

there are still some shortcomings suggesting that there is still much research work to be

done, including improvements on data and information support especially regarding

more details on lot sizing, cycle time and work in process buildup at each process.

Further research will address these issues applying the approach to similar problems. As

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part of an ongoing joint research project involving 12 small and medium sized ETO

manufacturers special attention will be given to the actual shortcoming regarding data

support in the presented ETO related value stream mapping approach. Moreover, the

aspect of production planning and control in this specific context must be addressed in

more detail.

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subcontractors

construction

site

2 trucks/day

SHIPPING

deliveres directly to the construction site

steel girders

steel plates

paint

small parts

INCOMING

GOODS

transiting parts

INCOMING

GOODS

Buffer for

transit parts

TACK WELDING

SEAM WELDING

COATING

PLANT 2

METAL SHEET

CUTTING

PLASMA

CUTTING

SAW

GRINDING PUNCHING

DRILLING

BENDING

Order

Department

Technical

Office

Production

Planning and

Control

Purchasing

Department

reservation, availability check

Internal

order

Purchase

order order per

fax/e-mail

zinc plating

SAW

THREAD

CUTTING

BENDING

Steel girders are delivered in the following states:

cut

cut + drilled

cut + notched

sanded

Suppliers „Direct“

supplier

production

papers Single part

drawing

shipping

list

CNC data

2

3

5

4

project timelines,

technical drawing

assembly drawing,

cutting list

1

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INCOMING

GOODS

METAL SHEET

CUTTING

cutting raw

materials

PLASMA

CUTTING

cutting raw

materials

SAW

cutting raw

materials

MACHINING

CENTER

Grinding,

punching,

drilling, bending

MANUFACTURING

PICKING

ZONE

Picking of

production

orders

I

Technical

Office Sales

Production

Planning &

Control

Puchasing

ASSEMBLY 1

tack and seam

welding

ASSEMBLY 1

tack and seam

welding

ASSEMBLY n

tack and seam

welding

ASSEMBLY

COATING

Corrosion

protection and /

or top coat

SHIPPING

order picking

and shipping

construction site direct suppliers

suppliers

zinc plating

I

I

I

orders

drawings,

BOMs

customer

order

purchase

orders

production

orders

pitches

Material that

has not to pass

through

manufacturing

goes directly to

the picking zone

I

I

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picking

list 1.1

picking

list 1.2

picking

list 1.n

customer

order 1

production

order 1.2

production

order 1.1

production

order 1.n

pitch

order 1.2.3

pitch

order 1.2.2

pitch

...

pitch

order 1.2.1

pitch

order 1.2.k

VSM-3 VSM-1 VSM-4 ... VSM-1

mfg.

docs 1.2.2

mfg.

docs1.2.3

mfg.

docs ...

mfg.

docs 1.2.k

mfg.

docs 1.2.1

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