Using Lean principles to reduce
2
U
SING LEAN PRINCIPLES TO REDUCE VARIABILITY IN THE
PRODUCTION PLANNING AT
V
OORBIJ
P
REFAB
B
ETON BV
.
Author
F.A. Weenink s1353071
Master Technology Management – Faculty of Economics and Business
Supervisor Voorbij Prefab Beton bv.
Ing. L.W. Plekkenpol Msc
Manager Operationall Excellence – Voorbij Prefab Beton bv.
Supervisor University of Groningen
Dr. ir. W. Klingenberg
Faculty of Economics and Business – department of operations
Co – assessor
Drs. A.J.J. Braaksma
Faculty of Economics and Business – department of operations
Date
3
M
ANAGEMENT
S
UMMARY
The purpose of this research is to improve the performance of Voorbij Prefab Beton bv. by using lean principles to minimalise the variability in the planning of the manufacturing process. In this way the daily capacity changes in the production planning at Voorbij Prefab Beton bv. are reduced. The solution for this problem had to comply with lean principles as stated by Liker (2004) and the lean attributes and tools included in the Voorbij Lean System. Because the solution had to comply with lean principles, it was investigated which lean implementation problems should be taken in account by VPB. This resulted in three problems that occur at VPB. These problems are the failure of their suppliers to deliver on time, cultural resistance and the lack of skill and expertise of lean manufacturing among the employees.
To find the root cause of the research problem, the company was analysed first. After analysing the different departments, the Lean Manufacturing Assessment Tool was used to find out how the company was progressing with their way towards being Lean. After this analysis of the company, the Five-why method is performed to find the root cause of the research problem. By using this method, several causes came forward. It was chosen to focus on the planning that did not conform with the capacity in the wood workshop, because it was indicated that this was the bottleneck. It seemed that the root cause of the research problem was the variability in the process of the wood workshop. Because of this, there were no normal times to make a planning conforming to the available capacity in the wood workshop. This caused the changes that are made on a daily basis.
To investigate a possible solution for reducing the changeover times in the wood workshop a literature review is performed. From this, two possible solutions came forward. One solution was based on planning in order to reduce the setup time. The other solution was SMED (Single Minute Exchange of Dies), designed by Shingo, which focused on reducing the actual process. Introducing SMED will lead to the biggest improvements.
In the last chapter, SMED was implemented. According to Moxham & Greatbanks (2001), prerequisites for starting SMED are not addressed by Shingo. Adoption and implementation of fundamental requirements to perform SMED are classified as SMED-ZERO. After SMED-ZERO, the first stage of SMED already caused a 30% reduction in changeover time.
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A
CKNOWLEDGEMENTS
This thesis is executed in order to graduate for the master Technology Management at the University of Groningen. The thesis is written during my internship and full time contract at Voorbij Prefab Beton bv.
First, I want to thank all my colleagues at Voorbij who supported me during my internship. My thanks go especially to Lard Plekkenpol, as my supervisor at Voorbij, for his support and valuable feedback. Our discussions helped me fulfilling this thesis.
Secondly, my gratitude go to my supervisor at the University of Groningen, Warse Klingenberg. Our meetings, face-to-face or over the phone, always pushed me in the right direction. I also want to thank drs. Braaksma for reviewing my final thesis.
At last but not least, I want to thank my family and friends for their support during the process of writing my thesis.
Franklin Weenink
5
T
ABLE OF
C
ONTENTS
MANAGEMENT SUMMARY ... 3 ACKNOWLEDGEMENTS ... 4 ABBREVIATIONS ... 7 TABLES ... 8 FIGURES ... 91 INTRODUCTION OF VOORBIJ PREFAB BETON BV. ... 10
1.1 Introduction ... 10
1.2 Short History ... 10
1.3 The Product ... 11
1.4 The organisation ... 12
1.5 The Voorbij Lean System (VLS) ... 12
2 RESEARCH DESIGN ... 14 2.1 Introduction ... 14 2.2 Problem introduction ... 14 2.3 Research objective: ... 15 2.4 Research question: ... 15 2.5 Research approach ... 15
3 DIAGNOSIS:THE LEAN PHILOSOPHY ... 17
3.1 Introduction ... 17
3.2 Lean principles ... 17
3.3 Lean attributes/ tools ... 19
3.4 Lean implementation problems ... 20
3.5 Conclusion ... 22
4 DIAGNOSIS:FINDING THE ROOT CAUSE ... 23
4.1 Introduction ... 23
4.2 The planning process... 23
4.3 The production process ... 27
4.4 Lean Manufacturing Assessment Tool ... 29
4.5 Five Why Process ... 33
4.6 Conclusion ... 36
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5.1 Introduction ... 37
5.2 Literature Review ... 37
5.3 Combine different jobs with similar setup requirements ... 38
5.4 SMED ... 40
5.5 Conclusion ... 42
6 CHANGE:IMPLEMENTING SMED ... 43
6.1 Introduction ... 43
6.2 SMED – Zero ... 43
6.3 STAGE 0 – Identifying changeover steps ... 44
6.4 STAGE 1 – Separating internal and external changeovers ... 45
6.5 STAGE 2 - Converting internal to external changeovers ... 47
6.6 STAGE 3 – Streamlining all aspects of the changeover operation ... 48
6.7 Conclusion ... 49
7 CONCLUSION ... 50
8 REFLECTION ... 52
9 REFERENCES AND APPENDICES ... 54
9.1 Journals ... 54
9.2 Books ... 55
9.3 Other ... 55
Appendix 1: An engineering diagram ... 57
Appendix 2: A table planning ... 58
Appendix 3: Examples of the LMA results. ... 59
Appendix 4: Structured way of transferring project information (Dutch) ... 60
Appendix 5: VSM Rebuild ... 63
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A
BBREVIATIONS
Abbreviation Name
5S Systematic approach to a clear and safe workplace
FEB Faculty of Economics and Business
FTE Fulltime Equivalent
LMA tool Lean Manufacturing Assessment Tool (UoG FEB)
LPS Last Planner System
OTED One – Touch Exchange of Dies
PPC Percent Plan Complete
SME Small to Medium-sized Enterprise
SMED Single-Minute Exchange of Dies
TPM Total Productive Maintenance
PD Production Drawing
UoG University of Groningen
VLS The Voorbij Lean System
VPB Voorbij Prefab Beton bv.
VSM Value Stream Map
WPD Work Preparation Department
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T
ABLES
Table 3-1 Toyota‟s building blocks (Liker, 2004) ... 18
Table 3-2 General lean implementation problems (Sosnowy, 2009). ... 20
Table 3-3 Lean implementation problems for SMEs (Sosnowy, 2009) ... 21
Table 4-1 Average production times of the production process. (Kuipers, 2008) ... 27
Table 4-2 Results of the actual rebuild times ... 35
Table 6-1 The production steps classified to internal or external time. ... 46
9
F
IGURES
Figure 1-1 The different departments within VPB. ... 12
Figure 1-2 The Voorbij Lean System ... 13
Figure 2-1 DDC model (de Leeuw, 2000) ... 15
Figure 4-1 The main process at the work preparation department. ... 24
Figure 4-2 An overview of the different planning schemes. ... 25
Figure 4-3 Changes in production capacity on a daily basis. ... 26
Figure 4-4 The difference between planned en real production time. ... 26
Figure 4-5 Process of the Wood Workshop. ... 29
Figure 4-6 Average Result LMA. ... 31
Figure 4-7 Daily analysis of the PPC from week 2 until week 34. ... 33
Figure 4-9 The Last Planner System at VPB. ... 34
Figure 5-1 Result after implementing the method of combining setup with minimal changes in requirements. ... 39
Figure 5-2 SMED: conceptual stages and practical techniques (McIntosh et al, 2000) ... 40
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1
I
NTRODUCTION OF
V
OORBIJ
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REFAB
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ETON BV
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1.1 Introduction
In this chapter a description of the factory is given as an introduction to Voorbij Prefab Beton bv. and its products.
1.2 Short History
In 1935 Cor Voorbij founded Voorbij Beton. In the beginning Voorbij Beton only produced rebar for the concrete elements. From 1958 the firm started to produce traditionally rebarred concrete poles. In the following years, more companies were founded by Voorbij and in 1988 these companies were combined. Voorbij Beton was renamed the Voorbij Groep. In 1996 they sold their shares to TBI Holding. At that time, the annual turnover of the Voorbij Groep was about 56 million euros. In 2004 the Voorbij Groep moved to the production location in Amsterdam. In 2007 the Voorbij Groep was divided into three companies (after takeovers and reorganisations); Voorbij Betonsystemen bv., Voorbij Funderingstechieken bv. and Voorbij Prefab Beton bv. (VPB). VPB also runs a factory in Germany (BFN). Part of the production location in Amsterdam is shown in the picture below.
Picture 1-1 Production Location of Voorbij Prefab Beton bv. in Amsterdam.
Hall 1
Metal W
orkshop
Wood
Worksho
p
T S Element retrieval ElevatorPole pro
duction
Carouse
l
WPD L o g . Concrete productionH
a
ll
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1.3 The Product
VPB is specialised in the production of precast concrete elements. These elements can be divided into standards and “bespoke”or “specials”. The standard elements of VPB are flomels, small electricity buildings, counterweights for Hitachi and piles. The last three elements are shown in the picture below.
Picture 1-2 above: counterweights and piles; below: electricity buildings
In addition to these standards, which form a strong basis, VPB can produce interesting alternatives for special construction projects. They are specialised in the production of complex purpose-built walls and linear structural elements, such as beams and columns. This research is focused on these bespoke elements. The elements can have many different forms and in addition a lot of different facilities can be placed in the elements. Inserted facilities are, for example: gains, screw sleeves, insert anchors, crane facilities, etc. The type of concrete that is used is of importance for the strength and quality of the precast elements.
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1.4 The organisation
VPB is a small to medium-sized enterprise (SME). VPB is divided into six departments (figure 1-1) but, since it is not a very big organisation, the lines of communication are very short. This makes VPB very flexible in, for example, setting up new projects or improvements to existing operations.
Figure 1-1 The different departments within VPB.
In the last strategic plan (2009-2014), the following five main goals were established: 1) Customer focus.
2) Productivity and Innovation. 3) Supplier focus.
4) Employee involvement, care and education. 5) Financial results according to the strategies.
Research is mainly focused in the development of point 2. VPB wants to improve and innovate productivity in the factory by optimizing activities in the Carousel, Wood Workshop (WW) and Rebar Workshop. In addition to that, they want to reduce inventory and lower normal times. The normal time is the time required by a trained worker to perform a task at a normal pace. To reach this goal, VPB constructed the Voorbij Lean System (VLS) in which they use the theories of Lean manufacturing to optimize their processes. The general philosophy of lean manufacturing is explained in chapter 3.
1.5 The Voorbij Lean System (VLS)
The delivery of correct and waste-free value to the customer is the goal of lean production at VPB. By eliminating waste, the throughput time from order to delivery is decreased. In addition to the waste mentioned earlier, VPB also formulated four indirect types of waste: latent skill, energy & water, breakdown and pollution.
The VLS is based on seven pillars as shown in figure 1-2. Every pillar constitutes a lean attribute or lean tool. The pillars are VSM, 5s & visual factory, continuous flow, pull, TPM, set up time reduction and standardized work. VPB started to implement the VLS in 2008 and began by implementing 5s. 5s stands for Sorting, Straighten, Shining, Standardizing and Sustaining. 5s is a philosophy and a way of organizing and managing the workspace and workflow with the aim to improve efficiency by eliminating waste, improving flow and reducing process unevenness. In addition to efficiency, this seems to heighten morale on the production floor and increases safety. After the start of 5s, they began implementing Visual Factory and VSM. VSM stands for Value Stream Mapping. In the VSM of the carousel (Kuipers, 2008), two subjects came forward that are of importance for the start of this research. These subjects were
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changes in the production planning and the throughput from the WW. Visual factory is a term to describe how information is distributed in a lean manufacturing environment. VPB has made the first step by placing planning boards in all departments. This enables necessary information to be easily accessible for those who need it. VPB did not start with the rest of the attributes and tools. These will be discussed later in this research.
Figure 1-2 The Voorbij Lean System
Picture 1-4 Above: stock at VPB (before) Below: stock at Hitachi (After) One major change that has been established because of this Voorbij Lean System is the step from make-to-stock to make-to-order. An example is the production of the counterweights. VPB used to stockpile the counterweights at their location. This caused high inventory levels, bad transport alignment, damaged products and bad financial results. Currently they only produce counterweights that are ordered and the stock is kept by the customer. This resulted in low inventory, two standardised shipments per day, no damage and a positive financial result.
Mainly due to the credit crisis, the market is decreasing and projects have to be accepted at a lower price than in a normal market condition, therefore profit needs to be made on the production floor. To achieve this, VPB started to implement the Voorbij Lean System to reduce waste on the production floor.
Customer satisfaction
VOORBIJ LEAN SYSTEM
P u ll s y s te m s T P M 5 S & V is u a l F a c to ry V S M S e t u p t im e r e d u c ti o n S ta n d a rd iz e d w o rk C o n ti n u o u s f lo w
Production, Logistics, Financials, Sales & Work preparation, P&O, Operational Excellence.
Review Planning Implementation
Mission: Economic Growth, Healthy Organisation, Optimal Company Profits
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2
R
ESEARCH DESIGN
2.1 Introduction
The purpose of this research will be described in this chapter and shows why this research is necessary and how this will be done.
2.2 Problem introduction
This research is being conducted because, in earlier research (Kuipers, 2008), it became clear that VPB did not achieve the planned daily production, due to large variabilities in the production process. The manager of the operational excellence department set up an assignment to research the way of planning at VPB and find solutions to stabilise the planning; by doing so they aim to improve the performance of VPB.
The variability in the process causes many changes in the planning. Variability exists in all production systems and can have an enormous impact on performance. The ability to measure, understand and manage variability is critical to effective manufacturing management (Hopp & Spearman, 2000).The variability law by Hopp & Spearman (2000) states that increasing variability always degrades the performance of a production system. In lines without workflow control, increasing process variability at any station will:
Increase the cycle time at that station.
Propagate more variability to downstream stations.Clearly, if an upstream workstation has highly variable process times, the flows it feeds to downstream workstations will also be highly variable. Therefore, to analyze the effect of variability on the line, we must characterize the variability in flows (Hopp & Spearman, 2000). In addition, Thomas et al (2002) concluded that reducing the variability in daily productivity is more strongly correlated to improved performance than reducing workflow variability. They also concluded that it is possible to have minimal variability in labour productivity even though there is high workflow variability.
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2.3 Research objective:
The purpose of this research is to improve the performance of Voorbij Prefab Beton bv. by using lean tools to reduce the variability in the planning of the manufacturing process. In this way the daily capacity changes in the production planning at Voorbij Prefab Beton bv. are minimalised.
2.4 Research question:
The following research question can be derived from the objective:
Can the variability in the planning of Voorbij Prefab Beton bv. be reduced using the lean principles?
The sub-questions below are formulated to answer the research question: SQ1: What are the lean principles?
SQ2: Which implementation problems can be expected by implementing the lean principles and attributes?
SQ3: What is the root cause of the variability in the production planning?
SQ4: Can this root cause be eliminated by applying a lean principle and/or an attribute from the VLS? SQ5: How can this lean principle or attribute be implemented?
The following limitations in this research are set:
This research focuses solely on the production in the carousel.
In previous research (Kuipers, 2008), it is concluded that the bottleneck in the process is the Wood Workshop.
There is no constraint on capacity.
The possible solutions have to fit the Voorbij Lean System.
2.5 Research approach
A structured approach is necessary to give a well founded answer to the research question. De Leeuw (2000) designed the DDC-model; a problem solution process. Diagnosis, Design and Change are the three main phases in this problem solution process. This process is illustrated in the figure below and adjusted to the situation of this research.
Figure 2-1 DDC model (de Leeuw, 2000)
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Diagnosis:
According to de Leeuw (2000), the start of a problem solution process is a signal (a request for help). The diagnose phase is a transformation of this signal into a management problem. A management problem is a situation where the management thinks that there are possibilities for improvement in certain areas. The term „problem‟ can therefore also cover situations of opportunities, improvements etc.
The goal of the diagnose phase in this research is to analyse the different area‟s related to the problem stated in the research design and to find the root cause. First, lean manufacturing is described, including the lean principles, necessary lean tools and possible lean implementation problems. Secondly, the different departments that need attention, the work preparation department (WPD) and its planning process and the production process are described. Further analysis is done for departments within the production process that need extra attention. Because lean manufacturing is a key element in this research, the progress of implementing the Voorbij Lean System is tested with the lean manufacturing assessment tool provided by the University of Groningen (UoG). In the end, the “five why” method is used to find the root cause of the problem.
Design:
In the design phase the diagnosed root cause of the problem statement is researched. It is expected that in this research a few opportunities will appear. In the end, this research has to result in a „concrete‟ solution. First, a literature review is performed to gain insight in the possible tools to solve the root cause. After this, a decision for the best tool is made. An elaboration of the chosen tool supports the change phase.
Change:
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3
D
IAGNOSIS
:
T
HE
L
EAN
P
HILOSOPHY
3.1 Introduction
The first fundamentals of the lean philosophy (hereafter: „Lean‟) have their origin in Japan. The Toyota production system is the basis for what is now called lean. Womack & Jones (2003) give a short explanation of lean: Lean provides a way to do more and more with less and less, less human effort, less equipment, less time and less space, while coming closer and closer to providing customers with exactly what they want. In addition they state, that lean provides a way to make work more satisfying by providing immediate feedback on efforts to convert waste into value. Waste means specifically any human activity which absorbs resources but creates no value (Womack & Jones, 2003). Toyota has identified various types of non-value-adding waste. These wastes are overproduction, waiting, unnecessary transport, overprocessing/ incorrect processing, excess inventory, unnecessary movement, defects and unused employee creativity (Liker, 2004).
This chapter is structured as follows. First, the lean principles are described (SQ1). Then, the lean attributes and tools used in the VLS are discussed in briefly. Finally, the lean implementation problems are described (SQ2).
3.2 Lean principles
The answer to the research question will be based on the lean principles. Therefore it is necessary to know what the lean principles are. In this paragraph two ways of formulating the lean principles are given. Womack & Jones (2003), use the following 5 principles on their way towards being lean.
Specify value
Value can only be defined by the ultimate customer. Value is only meaningful when expressed in terms of a specific product which meets the customer‟s needs at a specific price at a specific time. (Womack & Jones, 2003)
Identify the value stream
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Flow
After removing the waste from the value stream, the company should make the remaining value-creating steps flow. This means that products are continuously flowing through the company. No department is waiting for products to be able to continue their production.
Pull
A pull production process is a process where the downstream station asks for products when they need it, instead of a push system where the upstream station pushes its finished products to a downstream station. An upstream station should only produce when a downstream station asks for it. In this way overproduction, one of the wastes, is avoided.
Perfection
After performing the first four principles, a company needs to be challenged to strive for perfection. Getting value to flow faster always exposes hidden wastes in the value stream. And the harder you pull, the more the impediments to flow are revealed so they can be removed. Dedicated product teams in direct dialogue with customers always find ways to specify value more accurately and often learn of ways to enhance flow and pull as well. (Womack & Jones, 2003)
A more extensive list of lean principles is given by Liker (2004).
Principle 1 Base your management decisions on a long-term philosophy, even at the expense of short-term financial goals.
Principle 2 Create continuous process flow to bring problems to the surface. Principle 3 Use “pull” systems to avoid overproduction.
Principle 4 Level out the workload.
Principle 5 Build a culture of stopping to fix problems, to get quality right the first time.
Principle 6 Standardized tasks are the foundation for continuous improvement and employee empowerment. Principle 7 Use visual control so no problems are hidden.
Principle 8 Use only reliable, thoroughly tested technology that serves you people and processes. Principle 9 Grow leaders who thoroughly understand the work, live the philosophy, and teach it to others. Principle 10 Develop exceptional people and teams to follow your company‟s philosophy.
Principle 11 Respect your extended network of partners and suppliers by challenging them and helping them improve.
Principle 12 Go and see for yourself to thoroughly understand the situation.
Principle 13 Make decisions slowly by consensus, thoroughly considering all options; implement decisions rapidly.
Principle 14 Become a learning organization through relentless reflection and continuous improvement (kaizen). Table 3-1 Toyota’s building blocks (Liker, 2004)
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3.3 Lean attributes/ tools
Lean attributes are attributes that support the lean principles. Lean tools are used to achieve the result of the lean attribute. Because this research is constrained to the lean attributes and/ or tools mentioned in the Voorbij Lean System, only these attributes and tools are discussed.
VSM
VSM is a lean tool that stands for Value Stream Mapping. VSM is used to identify all the specific activities occurring along a value stream for a product or product family (Womack & Jones, 2003). The goal is to create an overview in such a way that wastes (as mentioned in paragraph 3.1) become visible. VPB then uses Kaizen (Continuous, incremental improvement of an activity to create more value with less waste (Womack & Jones, 2003)) to improve the process. According to Serrano Lasa et al. (2009), the VSM implementation is based on five phases: 1) Selection of product family; 2) Current State Mapping; 3) Future State Mapping; 4) Definition of working plan; and 5) achievement of working plan.
5S
5S is a lean tool utilized to create a workplace suited for visual control and lean production. The five S‟ represent the starting letters of five Japanese words: Seiri, which means to separate needed tools, parts, and instructions from unneeded materials and to remove the latter; Seiton, which means to neatly arrange and identify parts and tools for ease of use; Seiso, which means to conduct a cleanup campaign; Seiketsu, which means to conduct seiri, seiton, and seiso at frequent, indeed daily, intervals to maintain a workplace in perfect condition; Shitsuke, which means to form the habit of always following the first four S‟ (Womack & Jones, 2003).
Visual Factory
Visual Factory is the placement of all tools, parts, production activities, and indicators of production system performance, so the status of the system can be understood at a glance by everyone involved (Womack & Jones, 2003).
Coninuous flow
The lean attribute continuous flow is the progressive achievement of tasks along the value stream so that a product proceeds from design to launch, order to delivery, and raw materials into the hands of the customer with no stoppages, scrap, or backflows (Womack & Jones, 2003).
A tool that VPB wants to use to achieve flow is takt time. Takt time sets the pace of production to match the rate of customer demand and becomes the heartbeat of any lean system (Womack & Jones, 2003).
Pull systems
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TPM
TPM is a lean attribute/ tool that stands for Total Productive Maintenance. It is a series of methods (tools) to ensure that every machine in a production process is always able to perform its required tasks so that production is never interrupted (Womack & Jones, 2003).
Set-up time reduction
Set-up time (changeover time) is time spent in preparation to do a job. It includes time to replace fixtures and attachments on a machine and to adjust the machine until it produces a part that meets specifications (Nicholas, 1998).
Standardized work
This is a lean attribute that gives a precise description of each work activity specifying cycle time, takt time, the work sequence of specific tasks, and the minimum inventory of parts on hand needed to conduct the activity (Womack & Jones, 2003).
3.4 Lean implementation problems
This research is based on lean principles. Introducing a new method in a company is not always an easy switch. Also with the implementation of lean manufacturing problems will arise. Sosnowy (2009) did a literature research and made a list of important lean implementation problems. This list contains problems that can occur in general and problems that concern SMEs specifically. In table 3-2 the general lean implementations problems, as researched by Sosnowy (2009), are listed.
Problem 1 Lack of management commitment and understanding.
(Crawford et al., 1988; Ramarapu et al., 1995; Storhagen, 1995; Wafa & Yasin, 1998; Nicholas, 1998; Liker, 2004; Emiliani & Stec, 2005; Bhasin & Burcher, 2006; Herron & Hicks, 2008)
Problem 2 Lean does not increase overall performance when not implemented companywide
(Crawford, 1988; Emiliani & Stec, 2005; Bhasin & Burcher, 2006)
Problem 3 Companies that fail to configure their supply chain (e.g. suppliers and customers) are unable to apply flow production successfully.
(Nicholas, 1998; Wafa & Yasin, 1998; Emiliani & Stec, 2005; Bhasin & Burcher, 2006; Ramaparu et al., 1995; Fisher, 1997)
Problem 4 Companies that view lean as a set of tools or techniques instead of a direction will not produce sustainable benefits.
(Karlsson & Ahlstrom, 1996; Liker, 2004; Bhasin & Burcher, 2006)
Problem 5 If only a small selection of tools is implemented, production performance will not increase.
(Nicholas, 1998; Liker, 2004)
Problem 6 Cultural resistance towards change prevents a company from implementing lean principles and practices.
(Crawford et al., 1988; Groebner & Merz, 1994; Storhagen, 1995; Emiliani & Stec, 2005; Herron & Hicks, 2008; Dahlgaard & Dahlgaard-Park, 2006)
Problem 7 Companies often lack resources required for training and changes to take place.
(Crawford et al., 1988; Wafa & Yasin, 1998)
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Problems 1 & 2 should not cause a problem for VPB since management commitment and understanding are high. Respectively, they implement lean throughout the whole company, in production but also in supporting departments like the finance department.
Problem 3 has a larger impact on the ability to implement lean at VPB. Customers often do not comply with the engineering diagram made with VPB. In addition, suppliers often do not meet the delivery dates. For example, production drawings that arrive later than agreed on.
Since the understanding of lean is high in the management of VPB, as discussed with problem 1, problem 4 forms not a problem for the company. In the seven pillars of the VLS (figure 1-2) they clearly state directions they want to achieve and not only tools.
VPB is not restricted to a certain number of tools, although the effectiveness and efficiency should be kept in mind, which solves problem 5.
Cultural resistance (problem 6) forms a problem for VPB. Although in some departments the way to lean is accepted; there are areas where this is not (yet) the case. It is of importance that the management of VPB outlines the goal of lean more carefully among the whole company and show what can be achieved.
The lack of resources (problem 7) forms not a problem for VPB. The management acknowledges the time and money it needs and are willing to invest.
The following problems listed by Sosnowy (2009) are based on SMEs. Although he warns for the small amount of literature that the problems are based on, the problems are treated. This can be used for further research but can also be of additional value for VPB.
Problem 8 SMEs are unable to implement lean because it is difficult for them to establish a supportive culture.
(Achanga et al., 2006; Kumar et al., 2008)
Problem 9 SMEs are unable to implement lean because they lack financial resources.
(Achanga et al., 2006; Kumar et al., 2008)
Problem 10 SMEs are unable to implement lean because managers lack leadership and management skills.
(Achanga et al., 2006)
Problem 11 SMEs are unable to implement lean because employees lack skill and expertise.
(Achanga et al., 2006; Kumar et al., 2008)
Table 3-3 Lean implementation problems for SMEs (Sosnowy, 2009)
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3.5 Conclusion
Two different formats of lean principles were given (Womack & Jones, 2003 and Liker, 2004). It was chosen to use the lean principles of Liker, because these are more „concrete‟. The lean attributes and tools used in the Voorbij Lean System were discussed that propagate the lean principles.
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4
D
IAGNOSIS
:
F
INDING THE ROOT CAUSE
4.1 Introduction
The aim of this chapter is to find the root cause of the research objective. To find the root cause more information is needed about the assessed company. First, the planning process at VPB is described and after that the production process. In the research design some restrictions were set. One of the restrictions is that the research question has to fit the VLS, a tool that is used to assess VPBs progress towards lean manufacturing. At last, the “five why” method is used to find the root cause.
4.2 The planning process
The planning process at VPB consists of a few steps outlined in this paragraph. Most steps in the planning take place in the Work Preparation Department (WPD). Besides the WPD, the production leader has a big influence in the production planning.
4.2.1 Work Preparation Department
At the WPD the process from customer to production planning is controlled. The WPD only works with the bespoke precast projects while the logistics department organizes the standard products. The WPD consists of work preparators, salesmen and calculators. The work preparator makes the planning. Its function will therefore be outlined in more detail.
The main goal of the work preparator, as defined in his job profile, is: Taking care of an optimal preparation and monitoring of the projects, within the boundaries of production and the customer. To accomplish this, the most important duties of the work preparator are:
Construct and monitor the production plans. Receive, review and distribute production drawings. Contact point for ambiguities in the production process. Ordering of irregular (inserted) facilities.
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Figure 4-1 The main process at the work preparation department.
The Sales department of the WPD has the first contact with the customer and is responsible for making sales. The calculator supports sales by making quotations for the orders. Calculations are made using the most accurate information available. This information consists of the number of moulds that are needed, the delivery time and the complexity of the elements. After this, Sales and Calculation hand the information over to the Work preparator. The work preparator starts by preparing an engineering diagram.
In an engineering diagram (appendix 1), the time path of the projects process is outlined. Every project requires a few standard steps that are needed in order to guide the project. Examples of these steps are control of production drawings, approval for production by the constructor, production start of the moulds and delivery dates. The work preparator prepares this diagram using the planned delivery dates. From these dates, he calculates back using a few rules which are set by VPB. One of these rules is that the form on the production drawing, on average, is finalised and approved three weeks before start production. This gives the Wood Workshop enough time to prepare the moulds. When a project is much larger than average, this rule is adjusted to a longer period. The complexity of the project can also be a reason to adjust the engineering diagram. When a provisional engineering diagram has been made, it is sent to all stakeholders. In this way, they can give their approval and feedback of the planning as prepared by VPB. After the feedback from all stakeholders, the engineering diagram is finalised.
When the form on the production drawings is final, the work preparator prepares a table planning (Appendix 2). A Table planning is unique for every project and specifies the different tables that are to be used and which elements are made on these tables. The order of the elements is also of major importance. The following restrictions are used to make an optimal planning.
Delivery time.
Number of moulds calculated.
25 Size of the elements.
Type of table. Series production. Placement of cores.
Placement of inserted facilities.
The delivery times are the first priority in preparing a table planning. After this, the project is planned on the number of moulds calculated. In addition, the work preparator tries to achieve the shortest rebuilding times of the moulds by changing the order of the elements. This is where restrictions like element size or placement of cores comes into play. It is for example easier to rebuild a mould from a bigger to a smaller size than the other way around. The size of the rebuild also determines the number of days between two elements. This is mainly based on the experience of the work preparator. When there is almost no rebuild (for example series production), the element can be produced the following day. A relatively small rebuild is planned with one day between two elements and, with a large rebuild, two or more days are planned in between.
When the table planning is finished, the work preparator plans an appointment with the production leaders to discuss the planning in a project information meeting. In this meeting the following most important issues are discussed: the date of receiving production drawings, comments on the „to check‟ production drawings, to decide whether the first planning is feasible, number of elements and the repetition factor (number of elements that are equal), number of moulds that can be used, the reuse of moulds, other non-standard details etc.
Figure 4-2 An overview of the different planning schemes.
In Figure 4-2 an overview is given of all the different planning schemes. Every week a 3-week advance planning is distributed. In this planning, the work preparator tries to level the production quantity from day to day. This has to be done, because new projects are integrated into the overall planning of all the projects undertaken by VPB after the table planning is made. This means, while constructing a table planning, they don‟t confirm it with the overall planning. Because of this, there can be big differences in the overall planning on a daily basis.
The production leader of the carousel, element retrieval department and wood workshop provides the WPD every day with information about the specific elements that are produced each day. The work preparator incorporates this in the overall planning and from this prints and distributes the daily planning. Because of this there are still a lot of changes
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on a daily basis despite the levelling of the 3-weekly planning. In the figure below, the production rates per day are converted to people required on the floor. This gives an overview of the changes.
Figure 4-3 Changes in production capacity on a daily basis.
After some further analysis, it was also found that there is a big difference between planned and normal time on a weekly basis. In figure 4-4 this is outlined graphically. If the value on the y-axis is zero, there is no difference. When it is above zero, the real production time is higher than the planned production time and vice versa.
Figure 4-4 The difference between planned en real production time.
From interviews with the work preparators and production leaders, four important causes of the difference shown above could be listed. This list should be treated as anecdotal evidence.
1
The normal time is not set correctly.2
Waste in production because of late delivery of resources (for example the wooden mould) by internal suppliers.3
Occupation of fte (Full-Time Equivalent) on the floor is too low.4
Malfunction of the machinery.The late delivery of resources can result in waiting times in the carrousel and therefore lowers the labour productivity. Because of the big changes in normal time per day, as illustrated earlier, it may happen that there are not enough people on the floor to achieve normal time. This anecdotal evidence can be used for further research.
Number of people needed according to normal time per day
0,0 5,0 10,0 15,0 20,0 25,0 30,0 24 -1 -2 00 8 24 -2 -2 00 8 24 -3 -2 00 8 24 -4 -2 00 8 24 -5 -2 00 8 24 -6 -2 00 8 24 -7 -2 00 8 24 -8 -2 00 8 24 -9 -2 00 8 24 -1 0-20 08 24 -1 1-20 08 24 -1 2-20 08 24 -1 -2 00 9 24 -2 -2 00 9 24 -3 -2 00 9 24 -4 -2 00 9 24 -5 -2 00 9 time (days) nu m be r o f p eo pl e
Difference planned and real normal time
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4.3 The production process
The bespoke precast elements are produced in five steps:
1. Building/ changeover of the mould on the production table. (Wood Workshop) 2. Putting the rebar and extra facilities in the mould. (Carousel)
3. Pouring concrete in the mould. (Carousel) 4. Finishing of the poured element. (Carousel)
5. Removing the mould and storing of the elements. (Element retrieval department)
The moulds are built on specified working tables. During production these tables move around the factory. The inserted facilities and rebar are delivered by internal divisions. The inserted facilities are brought by external suppliers to the warehouse. At the warehouse these facilities are made ready for production. These facilities are divided and put in a blue box for every element.
Picture 4-1 Production tables moving through the factory.
In recent years, there has been a major shift in the complexity of industrial prefab buildings. For VPB this has resulted in a high variety of prefab elements instead of many series of equal elements. Due to this, changeovers have become a greater part of the total production time and therefore more important as they cause an increase of the throughput time of the tables. It is analysed that the largest production times are in the building/ changeover time of the mould (Table 4-1).
Production step: Average production time:
1. Building/ changeover time of the mould. 3.5 hours
2. Inserting rebar and other facilities. 1.25 hours
3. Pouring concrete. 0.25 hours
4. Finishing element. 0.5 hours
5. Retrieving the element. 0.5 hours
Table 4-1 Average production times of the production process. (Kuipers, 2008)
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4.3.1 Wood Workshop (WW)
In the WW the wooden moulds are build, rebuild, converted or renovated. The WW is split into two parts. In one section the parts of the wooden moulds are build and assembled. In the other part of the workshop the moulds are converted into new shapes or are renovated. The wood workshop is the starting point for new projects. When the production drawings of the project are ready to check, the work preparation department distributes the drawings to the production-/ team leader of the WW. The production-/ team leader checks these drawings on the following items:
Complexity of the elements. Quality of the production drawings. The use of standard sizes.
After this, the team leader checks the inventory of old moulds to ascertain if they can reuse them and in this way save money for new materials and save production time. Three days after the „ready to check‟ production drawings are distributed, the project information meeting as mentioned before takes place.
Picture 4-2 left: overview of the Wood Workshop; right: example of a mould.
Next, the WW has to decide whether they can produce the moulds within the time set (including working overtime) or that they need to outsource them. This decision is based solely on the maximum capacity available.
If the decision has been made to produce the mould in the wood workshop, the different parts of the mould are divided among the specialist carpenters of these parts. The different parts are, for example, side boards, head boards and cores. When these parts are ready, they can be put together on a production table that has already been cleaned thoroughly. The cleaning contains removing all obstacles from former moulds and the table is polished. After this, the mould is assembled. Next, the mould can be transported to Hall1 or the lift, from where the table can be moved to the carousel. After every retrieval of the element, the mould needs to be rebuild, converted or renovated. In general, these are called changeovers. If the project is finished, the table is stored away until it is cleaned again.
29 Figure 4-5 Process of the Wood Workshop.
4.4 Lean Manufacturing Assessment Tool
One of the constraints of this research is that the solution(s) of this research should conform with the VLS. An assessment is enabled to have an objective opinion of the status of lean manufacturing at VPB. The UoG FEB designed a tool to assess a company on its status towards lean manufacturing. In the next paragraph, VPB will be tested on ten attributes within lean manufacturing.
Ten attributes of lean manufacturing are formulated by the UoG FEB to avoid the waste as stated previously. These lean attributes are cultural awareness, workplace organization (5s‟s) & visual management, standardized work, flexible operations, continuous improvement, error proofing, quick changeover capability, total productive maintenance, material control & level production. The assessment tool contains ten attribute worksheets describing the lean best practices that constitute lean manufacturing. These worksheets all have 6-8 questions which are answered with a scale from 0-4 points. This ranges from „the practice is not found on the shop floor (0% occurrence)‟ to „the practice is everywhere in the plant, no exceptions (100% occurrence)‟. The attributes are explained below.
Cultural awareness:
To what extent the shop floor workers are involved and informed about the goals of the company is the main issue in cultural awareness. The company is tested on its openness and clarity of the processes to the shop floor workers. The initiative and the ability to solve problems independent is also researched among the shop floor workers.
Workplace organization & Visual management:
Within this attribute, the company is assessed on its cleanliness and well-structured work floor. In addition, the company is tested on accessibility of necessary information and effective communication. Positive side effects are that safety and errors are noticed earlier because of the improved visibility of the process.
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Standardized work:
To what extent all processes are standardized in the company is the issue with this attribute. Procedures are written for every function that should be used for training employees and to involve them in the process of improvement.
Flexible operations:
With flexible operations, the company is assessed on its focus towards shortening the throughput of the process. Plant lay-out, training of employees and equipment placement are used to improve flexibility.
Continuous improvement:
To what extent employees of the company are aware of the improvement processes. Employees should be trained, informed and motivated to think about possible solutions for the improvement processes.
Error proofing/ poka-yoke:
To what extent defects are minimalized. The processes and procedures should be designed in such a way that defects cannot occur or otherwise are recognised very quickly.
Quick changeover:
To what extent changeover times are minimalized. Changeovers should be scheduled and reduction techniques are used to optimize the changeover time.
Total Productive Maintenance (TPM):
To what extent TPM is implemented. Preventive maintenance activities are focused on increasing utilization and minimizing cycle time variation. In addition, it should be possible to track what maintenance is done.
Material control/ pull system:
To what extent the production process is designed as a material pull system. Upstream processes should be dependent on downstream production. Products can only be made on customer demand.
Level production:
To what extent the production is levelled. Processes in production are balanced or levelled in such a way that the difference between cycle times of linked processes is negligible.
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4.4.1 Results Lean Manufacturing Assessment Tool
After the introduction of the LMA tool, the assessment is performed. The assessment is executed by employees within the company. These employees are divided over different layers or departments in the organization. After the assessment is completed, an average of the main results are shown in table 4-6. In the question forms, the participants were asked to give a score on a scale from 0-4 points. In the results this is converted to a 10-point scale.
Figure 4-6 Average Result LMA.
The first thing that strikes is the small green figure. From this we can conclude that VPB probably scores insufficient on multiple attributes. All attributes will be discussed to see where improvements are needed or opportunities arise.
Cultural awareness:
VPB scores best and sufficient on their cultural awareness. This means that the employees have knowledge of the company goals. This is a result from the canteen meetings, a meeting where the CEO explains the financial and operational status of VPB and its goals, that occurs twice a year. In addition, employees have reasonable freedom and the ability to take initiative. Further research should be done to see where the real opportunities are within this attribute but since this is not a pillar in the VLS it is concluded as a sufficient score.
Workplace organization & visual management:
This is also one of the best scoring attributes at VPB. The lean tools 5s and visual factory are in a pillar of the VLS. These tools should lead to workplace organization and visual management. It is good to see that the use of these tools have a positive effect on the result of the LMA tool.
Standardized work:
VPB scores very low with this attribute. It is one of the pillars they did not start with yet.
0 2 4 6 8 10 Cultural awareness
Workplace organization & visual management
Standardized work
Flexible Operations
Continuous improvement
Error proofing/ Poka-yoke Quick change-over
Total Productive Maintenance Material Control/ Pull System
Level Production
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Flexible operations:
VPB scores insufficient on this point. VPB has tried to increase their flexibility on operations especially on the standard products. In this area they made big improvements but, since this is a smaller part of the company than the bespoke products and not included in the VLS, they score a lower than 50% occurrence.
Continuous improvement:
This is not one of the weakest points of VPB but still insufficient. Especially team leaders, production leaders and other higher placed employees are trained to think of continuous improvement. A great opportunity lies in involving the shop floor workers in the kaizen process, because they actually do the work and therefore have a different insight in improving the process.
Error proofing/ poka-yoke:
Error proofing is not one of the pillars of the VLS. Therefore it can be explained that VPB does not score very high on this attribute. This could also be an opportunity for VPB.
Quick change-over:
This attribute is added to the VLS as setup time reduction. This attribute does not score high and is still insufficient. VPB did not start with this pillar yet but this attribute could become a big opportunity after this research.
Total productive maintenance:
TPM is also one of the pillars in the VLS. VPB has not yet started with implementing this attribute and therefore scores low in the LMA tool.
Material control/ pull system:
This attribute is one of the pillars in the VLS. VPB did not start with this pillar, in this way the low score can be explained.
Level production:
Level production is an attribute that VPB calls continuous flow. They have not yet started with this pillar and is therefore still insufficient.
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4.5 Five Why Process
A further analysis of the variability in the planning of the manufacturing at VPB is performed to find the root cause of the problem. Nicholas (1998) states that to come to the root cause, a lean production method is to ask „WHY‟ five times. This procedure is intended to assure that the root causes and not merely superficial symptoms are detected.
1. Why are there changes in the production planning?
In paragraph 4.2 it was analysed that the work preparation department smoothes the production planning that is constructed three weeks in advance. We also analysed that there are a lot of changes in the daily production planning. Not producing what is in the planning is one reason there is much variability in the production planning. In figure 4-7 a graph of the percent plan complete (PPC) is constructed. The PPC is a method derived from the Last Planner System (LPS), a planning and control system based on lean principles. Replacing optimistic planning with realistic planning is the main object of LPS. The PPC is an element of the LPS to measure the work flow variability.
Figure 4-7 Daily analysis of the PPC from week 2 until week 34.
As can be seen in figure 4-7, the constructed planning is often not followed. On average, two changes in production take place on a daily basis. These changes consist of tables moved to the next day or future planned tables moved to the current day. Since one table can take up a few hours in production, movement of these tables can have a significant influence on the required capacity. It is not only of importance where the variability comes from but also who is responsible for these changes on a daily basis.
Planning is almost always done by different layers in the organization. LPS is about the individual or group that decides what physical specific work will be done. This work is unique because it drives direct work rather than the production of other plans. This individual or group is called the “Last Planner” (Ballard, 2000). The last planner says what WILL be done and should be the result of a planning process that best matches WILL with SHOULD within the constraints of CAN.
The last planner of VPB should be the WPD, but this last planner lies on a different spot within the organization. The process can be constructed as shown in figure 4-9. What SHOULD be done is stated in the engineering diagram and what CAN be done is provided by the production leader. From this information, a table planning and daily planning is constructed about what WILL be produced. As can be seen in the figure, after what will be done is supplied to the production floor, the production leader influences this plan by introducing a pouring and retrieval planning. In this
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planning, the production leader decides in what order the elements are poured and retrieved. However, he does not just change the order of the elements but also which elements are produced.
Figure 4-8 The Last Planner System at VPB.
2. Why does the production leader have to make changes in the daily
planning?
WPD should be the department that provides the production planning to the floor but, as we concluded in the former paragraph, the production leader is responsible for the final planning. To answer the second question an interview with the production leader was held and data analyses were performed.
The main reason for changing the planning is that the mould is not finished. This has different causes. 1) The rebuild of the moulds does not meet the available capacity.
2) The mould is damaged and therefore the rebuild takes longer. 3) Moulds arrive too late from the element retrieval department. 4) Parts of the mould are not ready in the wood supplying department.
The consequence of all these reasons is that the mould arrives too late in the carrousel to make it ready for pouring. In this case, the production leader moves the element to the following day. In addition, elements need to be pulled to the current day. This is necessary to keep the carrousel busy (avoid waiting time) and fit the production planning to the available capacity in the carrousel. This results in even more changes within the “final” production planning.
Four causes have come forward with this question. A decision has to be made which cause has the biggest impact. Empirical evidence has proofed, that it can be concluded that the most important reason for changes in the production planning happen because the planning does not conform with the capacity in the wood workshop (number 1).
3. Why does the production planning not meet the capacity in the Wood
Workshop?
In paragraph 4.2, it is described that the WPD first makes a table planning. This planning is based on the order of the elements to meet the delivery dates. The WPD tries to make the order of the elements in such a way that the rebuild of the mould is as small as possible. For example, they try to put series of the same elements together. Between the
Operations Planning Business Planning
WPD
Engineering diagram
Table planning & dayplanning Info of production leader WPD Supplier Customer Info of customer Demand customer
Production productionActual
Resources
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elements of each table WPD inserts rebuild days, if necessary, to prepare the moulds. When the table planning is finished, WPD inserts this planning in the overall planning. Only now they can see what the influence of the table planning has on the overall planning. Once a week, WPD smoothes the production planning in such a way that the capacity in the carrousel does not fluctuate too much. Because the overall planning is solely based on the capacity in the carrousel this can change a lot in the wood workshop. Therefore the capacity problem in the wood workshop cannot easily be solved by increasing the capacity.
4. Why is the planning solely based on the carrousel?
To answer this question research was done in the work preparation department, where they construct the production planning. The planning program that is used by VPB only plans the day that elements need to be poured. Normal times for the carrousel are used to determine the required capacity. If moving of the elements in the program occurs, the influence on the capacity in the carrousel is immediately visible. In the planning program WPD cannot see the required capacity for the rebuild of the moulds in the wood workshop. The planning program does support the option to see the required capacity in the wood workshop but this is not used because of the absence of normal times for the wood workshop.
5. Why are there not any normal times for the wood workshop?
WPD does not have normal times for the wood workshop and this is why they cannot plan on the capacity that is available in the WW. From empirical evidence, it became clear that there are not any normal times of the wood workshop because the variability in the process times are very fluctuating. To make sure that this is the real problem, time measurements are taken of rebuilds during a project. In table 4-2 the results are outlined.
Time in hour(s) Average Standard deviation Minimum Maximum 3,2 1,9 0,5 6,5 Table 4-2 Results of the actual rebuild times
An average of 3,2 hours with a standard deviation of 1,9 hours indicate that the rebuild times are very fluctuating. Hopp & Spearman (2000) state that if an upstream workstation has highly variable process times, the flows it feeds to downstream workstation will also be highly variable. Sammadar (2001) states that a reduction in setup time will cause a reduction in its variance. In absolute measures, when the setup time is reduced, the difference between the maximum and minimum setup time is smaller.
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4.6 Conclusion
37
5
D
ESIGN
:
I
NVESTIGATE A POSSIBLE SOLUTION TO SOLVE THE
ROOT CAUSE
5.1 Introduction
In chapter 4, it was concluded that the process variability in the wood workshop should be reduced. In addition, it was concluded that the process variability can be reduced by reducing the setup time (Nicholas, 1998). In this chapter a literature review is performed to show which alternatives there are for reducing setup time. After the review, two tools are investigated in more detail to be able to make a good decision for the most suitable tool to use at VPB.
5.2 Literature Review
Setup time is time spent in preparation to do a job. During much of the setup time, the „machine‟ is shut off and produces nothing. During the rest of the setup time, the „machine‟ is running and producing parts but, until the „machine‟ is fully adjusted, the parts are nonconforming and must be scrapped or reworked (Nicholas, 1998). According to Nicholas (1998), the usual ways that companies deal with setups are:
1) Increase the skills of setup personnel. 2) Minimize product variety.
3) Combine different jobs with similar setup requirements. 4) Use large lots.
The first way puts setup responsibility into the hands of a few highly skilled workers; the other ways minimize the number of required setups. These can reduce the setup time in total but are not solutions to minimizing the time per setup. Instead, all of the above „solutions‟ bow to the fact that setups are often complicated, time-consuming and costly (Nicholas, 1998).
The smaller the difference between products, the smaller the difference in processes and operations that make them. This results in less setup time between the products but not all companies have the choice to reduce their variety in product offering. It is also a possibility to schedule the production process in such a way that the successive products have a minor change. This ignores other planning priorities, such as due dates and results in jobs being finished earlier or later than needed. The last of the usual way is producing in large lot sizes. The larger the lot size, the smaller the effect of the setup on each unit. Mainly, the longer the setup time, the greater the impact of producing larger lots on reducing unit operating time (Nicholas, 1998)
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major drawbacks. They limit the possibility of product diversity, reduce quality and flexibility just to have fewer changeovers.
If changeovers are considered as variable, flexible and improvable, it is necessary to change the changeover procedure. Changeovers should be made more simple so that every employee can do them and the time they cost have to be reduced. Simplifying changeover procedure and reducing changeover time provide benefits in quality, costs, flexibility, worker utilization, capacity and lead times and process variability.
The foremost authority on setup reduction is probably Shigeo Shingo. With the SMED methodology, he was able to achieve astonishing improvements on setups for metal-working processes in the automotive industry. It turns out that this method can be universally applied to changeovers and setups in all kinds of processes and industries (Nicholas, 1998).
5.3 Combine different jobs with similar setup requirements
One of the usual ways that companies use to reduce setup time is to combine different jobs with similar setup requirements. In literature, empirical evidence was not found for the results after implementing this method. Therefore, a pilot was conducted to test this method to make a funded and good decision for the solution to the root cause. One of the lean principles stated by Liker (2004), was to use visual control. The purpose for visual controls in lean management is to focus on the process and make it easy to compare expected versus actual performance. The status of virtually every process should be visible in lean management (Mann, 2005). Therefore visual control was used with this method. The goal of this method is to decrease the changeover time of the moulds by adjusting the order in which the elements on a table are planned.
A mid-sized project was chosen to conduct this pilot. First, a new structured way of transferring information to the different departments was implemented. Feedback from these departments to the work preparator should increase the quality of the planning. In appendix 4 this way of information transfer can be found.
The second step was to make a big planning board where the whole planning of the project could be visualised. Picture 5-1 shows this planning board.
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After the first feedback meeting, the work preparator made the first conceptual planning. After that, the different departments gave their feedback by applying orange stickers on the planning where they saw possible improvements in the reduction of the setup time. After repeating this process several times, the work preparator made a final planning. In the figure below, the result in average changeover time from the first planning and the final planning is shown.
Figure 5-1 Result after implementing the method of combining setup with minimal changes in requirements.
By applying this method, the average changeover time was decreased by 4.3%. It was concluded that this was a very little improvement compared to the amount of extra work it took. In addition, this method does not improve the actual changeover process on the work floor, therefore the variance between the setup times did not decrease.
Average changeover time
154 156 158 160 162 164 166 c ha ng e ov e r ti m e ( m inu te s )
