This chapter is made based on reviews of the existing research that related to project title such as lean manufacturing, value stream mapping, simulation and others important factor that correlate to project title. Besides, in this chapter also contain information and discussion that were relevant and need to consider before beginning the project.
2.1 History and Overview of Lean Manufacturing
The lean manufacturing begins when the westerner has realized the potential of Japanese car maker in producing a car with a mass production of high quality product at a lower cost. Lean is derived from the Toyota Production System and been adapted by the western in their work culture called lean manufacturing and was famously studied with them for that. The produce of the book relates to lean by to Womack et al (1990) title "The machine that changed the world: The story of lean production" that has made the mindset of US manufacturer to change.
Previously, there is a huge gap between Japanese and Western automotive industry. But the study based on Toyota great success at NUMMI (New United Motor Manufacturing Inc.) That made a Western automotive industry gap with the Japanese to become closed. It is important because the Japanese companies have already developed their manufacturing system to a level of production at less human effort, less capital investment, less flooring space, tool, material and time that conclude to a less overall expense (Womack et al, 1990).
The meaning of lean represents a whole system that makes use of fewer inputs in order to create the same output compared to those created by the traditional mass production system. Meanwhile Marchwinski et al (2004) clarifies that lean is a production system for managing and organizing the product development, operations, suppliers and customer related by reducing the 7 waste. When compared to the previous system of mass production, then lean in manufacturing will make products with fewer defects that achieved the demand require. The usage of this lean philosophy can be done with focus on reducing waste in manufacturing by operation management control. The 7 types of waste that need to be eliminated is transportation, inappropriate process, motion, waiting, over processing, unnecessary inventory and also defect.
Lean also can be understood to a concept of value which refers value in customer perspective that differs from the traditional production point of view (Carreira, 2005). In explanation, the value is divided into two which is value added and non value added. Activity that customer willing to pay is referred as value added where the product or service undergo a process which transform them into a more complex state towards finish product. Meanwhile the non value added literally activity that the customer does not want to pay because the activity does not change the product or service into another thing but remain same for example inventory stage. To understand better on lean manufacturing, first one need to be acquainted with the basic principle and techniques as listed below.
2.2 Lean Principle
Lean is a philosophy that began with five principles are also known as lean thinking. In within the manufacturing environment, by understand the principle is basically a basic step before knowing deeper in lean and to improve it. Below is the step of lean principle that follows:
Lean Principles
Figure 2.1: The five key principles of lean thinking (Womack et al, 1996)
2.2.1 Identify Value
The critical starting point for lean principle is identifying value which entirely referred to customer perspectives. The information of product that a customer willing to pay for and only are defined by the customer to is the value of significance (Womack et al, 1996). The producer exists because of the value comes from customer point of view and was created by producer (Womack et al, 1996). Usually producer tends to make what they already make and the customer can only settle for what they offered. The situation shows that the producer does not see what customer really want and when customer no longer accept what has been offered, the producer then will lower their price as a technique to persuade customers to purchase back. It is really important to identify the value or what customer view because the indicator on what activities that add value, activities does not add value but cannot be avoided and activities that add no value and can be avoided can make customer would prepared to pay for the add value product produced by.
2.2.2 Map the Value Stream
The second step in lean principle is to identify and map the value stream. A value stream compresses all of the action, both value added and non-value added from product overview starting at the raw material and finish in the hands of the customer (Duggan et al, 2002). A value stream map is a tool used to chart the flow of materials and information from the raw material stage, through the factory floor, to the finished product. It will provide from starting to delivery process that add value and does not add value to customer perspective. The purpose of the map is to help identify and eliminate waste in the process by providing a systematic approach that empowers people to plan how and when they implement and changes can be made that make it satisfied to customer demand (Tapping et al, 2002).
2.2.3 Create Flow
The third step in lean principle is creating flow by eliminating the waste. According to Womack et al, (1996) flow can be referred as progressive achievement of tasks along the value stream. It is for the product to begin from raw material into customer hand without no breakdown, scrap, rework or backflow. In other word, products need to move continuously from a process to another process without stopping or having to wait in the manufacturing plant. It can be done by putting an effort to eliminate waste or obstacle along process flow and thus resulting in minimizing the non value added and maximizing the value added activities.
2.2.4 Establish Pull
The fourth step in lean principle is to establish pull. The concept of letting the customer pull the product for you as they need rather than pushing products onto the customer is the pull theory (Womack et al, 1996). Production only response to the customer demand by making what the customer wants and when only the customer wants it. The idea is that nothing is made until it is needed, and then made as quickly as possible. Pull also need the product to be sold or deliver at the same time it was produced. In order to establish pull, it requires the ability to design, schedule, and make just what the customer needs and when the customer want it.
2.2.5 Seeking Perfection
The final step in lean principle is seeking perfection or continuous improvement. The concept behind perfection is there is no endless opportunity to improve by reducing costs, scrap, mistakes, space and etc. Perfection are an aspiration goal and can be only attained by definition. However, there is always room for more continuous improvement during the process of pursuing perfection in the system.
2.3 Lean Manufacturing Tool and Techniques
Lean manufacturing is philosophies that reduce time between customer order and product delivery by eliminating the waste in the production line. Another perspective of lean is to attain same production output with less input such as time, space, human effort, raw material and importantly it is direct for less production cost. Lean manufacturing consists of many tools and techniques that are purposely to improve the manufacturing system. The tool and technique that can be used is Kaizen, Kanban, and others. In this following section will explain a brief description about the tool and technique in lean manufacturing that has a relation to the study.
2.3.1 Value Stream Mapping (VSM)
This VSM is a technique originated from Toyota Way and used to identify opportunities for improvement in the production line by helping manufacturing companies to identify the improvement opportunities. Originally, at Toyota this method is known as "Material and Information Flow Mapping" (Rother et al, 2003). The easy to understand characteristic of VSM for its flow of material with information such as cycle time, up time, down time has made it favorable in lean tool. As explained by Tapping (2003), when the usage of correct tool can ensure the workflow improvement to become smooth from beginning process until delivery.
When discussing about VSM, the focus should be on the whole picture and not to focus only on parts or single processes. The aim is to strive for a long term perspective although at first to start in beginning lean implementation may seem too much (Rother et al, 2003). VSM is a tool used in lean manufacturing that providing the flow of material into several processes with information require to deliver to the customer. The VSM is beneficial and easy to use since it only requires a need of pencil and paper as a tool that used to draw the process and information flow.
It is done by choosing the product family and followed through the plant by process flow and observed. It is suggested to ask key questions to find the waste element during the VSM study. The VSM will be drawn up carefully and every process in the current state is measured. After drawing the current state an improved future state is drawn. The elements of VSM include customer loop, production control, supplier loop, information flow and lead time data bar with critical path that provide a full view of the whole supply chain from customer's requirements to supplier's deliver (Lixia C et al, 2010).
Include in the value stream mapping is also the value added and non value added activities. According to Lovelle, (2001) the value stream mapping is a powerful but yet a simple tool which allows the user to see the waste throughout the stream. Although in conventional ways, VSM is created by using a piece of paper and pencil. But nowadays it has advanced to the use of software maps such as the Microsoft Excels, Microsoft Visio and others.
Below is the explanation regarding the creation of a VSM, it can be divided into five basic steps:
Identify the product.
In identifying the product, it is important to choose what product or part for VSM will be focusing on and to avoid it became too complicated. The product that was select also can be sharing a common process.
Create a current VSM.
Then follow by current VSM that usually step that detect waste or non value added in the system. It is based on scope choose earlier and the initial idea of brainstorming might help to determine any missing information required. Then from the information the current value stream mapping (CVSM) was plotted.
Figure 2.2: Current Value Stream Map (Yang-Hua Lian et al, 2002)
Evaluate the current map, identify problem areas.
Followed by evaluation which is a crucial step in the VSM. This is when the VSM is analyzed and problem area was identified. In this step, the possible about waste is identified. In this step also, the Takt time of production can be calculated and compared to the process flow. This is where the room of improvement activity can be focused on.
Create a future state VSM.
Meanwhile the future state of value stream mapping is based on lean improvement or by Kaizen that related to the problem area or non value added. This can be done by changing the current process of improvement in order to minimize problems or non value added.
Figure 2.3: Future Value Stream Map (Yang-Hua Lian et al, 2002)
Implement the final plan.
Lastly implementation step is to create a more standard operation. It is executed by changes the system in the stream flow of product to achieve more efficient production line.
As shown in Figure 2.2 and Figure 2.3, it shows the typical value stream that consists of basic information that necessary. There is information flow, process flow, material flow and production data. According to Sayer et al (2007), the VSM usually contains such as follows:
Process Steps : The VSM shows the process steps in the value stream map represent by icon represent the process.
Inventory : The VSM highlights storage and the amount and movement of work in- progress within the process.
Information flow : This is supporting information required that will show by the diagram on the VSM. This can include orders, schedules, specifications, Kanban signals, shipping information, and more.
Box score : The box score includes in VSM as key information that attain the value of production. It includes the information of distance travel, parts produced per shift, scrap, pieces produce per labor hour, change over time, inventory, uptime, downtime and etc.
Lead time : The lead time is attached at the bottom part of VSM and it indicates the performance of the value stream. Definition of lead time is referring to the amount of time for one piece part to go through all the process. It is divided into value added and value added potions, which the value added is up meanwhile the non value added is down the potion.
Takt time : A box in the upper-right-hand corner of the VSM and has been used to counterpart the pace of work towards the average pace of customer demand. This rate is determined by the formula of production time available divide by the demand. Ideally, all steps in the value stream should then produce according to this rate.
C:\Users\Iskandar\AppData\Local\Temp\msohtmlclip1\01\clip_image001.png
The basic icon use in VSM of current or future is almost the same, it is not standardized and there are many variations of this icon that has been used. The icons have been used as visual represent for various tasks and function within the map. Below are sample of VSM icon that had been used:
C:\Users\User\Desktop\psm\vsmicon.jpg
Figure 2.4 : Show the basic icon in Value Stream Mapping (William G. Sullivan,2002)
2.3.2 Kaizen
Kaizen originally a method of continuous improvement that being used by Japanese management to improve for a better productivity but it is also to teach worker along the process how to perform their work and eliminate waste in through standardization. (Kai) means change and (Zen) is to become good. Kaizen is an activity that is a good and relevant example of bottom up structure of continuous improvement. This is because people in all levels of organization from Managing Director down to operator worker can be involved.
In manufacturing settings, Kaizen can take place in many forms such as reduction of inventory, process simplicity and reduction of defective parts until the simple thought such as cleaning. The methodology in Kaizen is to make changes and the resulting need to monitor so that adjustment can be made until it become stable. This is important because, Kaizen is not only just to continuously improve without monitoring, to monitor is important because to make sure the changes is stable without any problem occur. Then standard of work for Kaizen need to be applied to make sure the worker is done according to the changes that made. Standard are the basis for a comparison and without standard cannot objectively tell what has changed or be improved. Kaizen with standard work only can possibly make it a success.
2.3.3 5S
The 5's are a tool used to improve the condition of working area by eliminating unwanted and unnecessary item and lead to a better productivity . It is also acts as process improvement by cost reduction and increase worker productivity when work in a conducive working area. The 5's is originally produced by the Japanese and then translate into another language as well. The 5'S tool is sort, set in order, shine, standardize and sustain are explained as listed below.
Seiri - Sorting - Sisih
The meaning is to go through all the tools and material in the plant area by only keeping items that essential and need to be used for the current process. Other unused tool and item will be stored or discarded. This can ensure fewer hazards and less clutter to interface during work done at current workplace.
Seiton - Set in order- Susun
This process is the extension of Seiton and has focused on efficiency of the tool used. The goal is to arrange tools, equipment and parts so it will encourage work flow. Tools and equipment should be in place where they will be used. Process are also should take place so it can maximize productivity. The quote that usually used to describe this situation is to make sure there must be a place for everything and everything need to be in its place. Supposedly, by set in order means that all tools or equipment has its own place and after use it need to be placed back to its original place. The tool also needs to be placed in the related process required only.
Seiso - Shine - Sapu
It is simple meaning but yet stills the important and cannot take for granted in the manufacturing environment. Seiso means the need to keep the workplace clean and neat by making sure the work area is cleaned every time during service. If capable, the cleaning process not only done during early shifts or before shift end, but can be done during there is no production or whenever the workplace are not clean and tidy. This can lead to worker satisfaction and increase the worker productivity.
Seiketsu -Standardize - Seragam
Standardize means that work practices operate consistently and in a standardized manner or according to the work instruction. In deep meaning, the standard work is in the form of procedure or work instruction to act as a rule to the worker to obey in their work practice. The standard prepares also need to be clear and easy to understand. Before doing this, the worker also needs to be responsible for the first three 'S' before they can implement a good standardize work.
Shitsuke - Sustain - Sentiasa email
This is processed to maintain high standards and reviewing those standards. In other word, sustain refer to maintaining standards and keeping the facility in safe and efficient order day after day, month by month and year after years. To sustain is hard if the worker takes for granted. In order to sustain require a lot of passion to improve the work surrounding. By having notice regarding the 5S at the manufacturing center may help the worker and act as warning system for them.
2.3.3 Kanban
Kanban comes from a Japanese word that means signboard and concept has been applied in lean and also known as Just-In-Time (JIT) or Demand Scheduling. Kanban operates as the meaning suggest as a visual indicator to create "signal" show needs for the item. This signal can refer as demand for one process step to another production line. Kanban will be control by the operator since they only produce a product based on the visual signal sent by customer. The Kanban card is usually a printed card where it does contain information such as part name, quantity, description and etc. The use of visual signal in Kanban allows the managers or supervisor to see the production schedule just by glance at it.
The idea of Kanban is it acts as a pull system that determines the need to produce according to the actual demand of customer. In manufacturing, the product will only manufacture when there is a "signal" shows the need of part. This is contrast to push system where production will keep producing part although without demand and being controlled by the scheduler. So the Kanban schedules will replace the needs of daily or weekly production schedule. But it is still not replace planning completely because Material Resource Planning (MRP) still used to plan the Kanban and work by empowering the operator to control the production line.
The purpose behind Kanban is also to reduce the level of inventory and thus will reduce the risk of inventory holding. The inventory can be minimized since the production will only produce part that's needed. The inventory will then ideally holds the amount of raw material and parts that will keep the production flowing, the order for a new part will only issue when these parts are actually needed.
2.3.4 Cellular Manufacturing
Implement lean require cellular manufacturing which is a basic tool of lean . It can define as a cell consists a combination of equipment and workstations that are arranged in an organized to that maintains a smooth flow of materials and components through the process (Wilson, 2009). It also has assigned operators that have qualities and trained to work at that cell. Usually it is arranged in C or U shape to ensure the flow of raw material and finished goods easily to be monitored. The arrangement also covers less space than long assembly line and by arranging people and equipment into cells has great advantage in terms of achieving lean goals.
There are lots of benefits of cellular manufacturing, one of the benefits of cells is the one-piece flow concept, which states that each product moves through the process one unit at a time without sudden interruption, at a pace determined the customer's need. Extending the product mix is another advantage of cellular manufacturing. The importance of having flexibility in the process according to Feld (2000) is that when customer demand high variety of products at a faster delivery rate, the flexibility can still make production to accommodate their needs.
Apart from all tangible benefits, the important advantage of cellular manufacturing also went to the familiarize between operator that understood each other operation very well because of the closed loop arrangement of machines, operators inside the cell. The improve relation among operators will improve productivity and benefit company as overall.
2.3.5 Time Studies
In late 19th , Frederick Winslow Taylor is responsible in introducing the stopwatch time study, until today it is still the most widely used time study methods. Basically the time standard is developed by time studies on observations of one worker taken over a number of cycles. It is applied to the same task perform by the worker in the organization. The basic step in time study based on William J et al (2010) are as the following:
Define the task to be studied with informing the worker that study will perform on them
Precisely divide the task according to the element.
Decide how many times to measure the task by determine the number of cycles to observe.
Record the job timing and rate the worker's performance.
Compute the average observed cycle time. The average observed cycle time is the arithmetic mean of the times for each element measured, adjusted for unusual influence for each element:
Determine performance rating and then computes the normal time for each element.
Calculate total normal time of task by adding the normal time of each element.
Compute the standard time. This adjustment to the total normal time provides allowances such as personal needs, unavoidable work delays and worker fatigue.
Normal time does not include such factors as personal delays (getting drink, going to restroom), unavoided delays (machine repairs, waiting material) or rest break. The allowance factor can be based the job time or time worked.
2.4 Waste
Waste can be defined as the activity that add cost but do not add value to the product. Waste definition according to Magee (2007) is a kind of activity in a process that consume more resources and lead in the decrease of productivity efficiency, quality and increase lead time as well. Previously, lean manufacturing only classified under seven categories of waste only and moving through the years, many in lean community has considered eight categories which are under utilized or unused creativity (Carreira, 2005). The seven categories of waste as defined by Liker (2004) are as follows;
Overproduction - Product to be produced is more than it is require that lead to other waste at inventory, transportation and manpower.
Waiting - Production are stop because of worker need to wait for raw material, machine or information before can proceed with the next process and this lead to unproductive. The waiting can occur in various ways for example, due to unmatched worker/machine performance, machine breakdowns, lack of work knowledge, stock outs and capacity bottleneck.
Transportation - Unnecessary motion by carrying work in process (WIP) that delays the movement of material or product.
Over processing - Using unneeded process to produce parts. This over processing may happen because of improper tools, product designs that lead to over processing. This kind of waste to time consume and machines which do not add any value to the final product.
Excess Inventory - It is referring to unnecessary raw material and includes WIP that cause waste in obsolescence, damaged goods, transportation, storage costs and delay. Also, the extra inventory hides problems such as production imbalances, late deliveries from suppliers, defects, equipment downtime, and long setup times.
Unnecessary Movement - It indicates any unnecessary motion that the workers or material movement that have to perform during their work. For example movement during searching for tools that brings no value to the product or process.
Defects - It is occurring when a product failed to meet the specification of products that may lead towards customer dissatisfaction.
2.5 Simulation Modeling
According to El-Haik et al (2006), simulation is an activity based on mimics or imitating the actual system using entities such as computers. It works by focusing on the process flow, logic and dynamic. While Harrel C et al (1996) interpret that the simulation can be considered as a representative of the real world where in reality simulation created to find a design solution that leads to the best solution can be created. By using this simulation model, the experiment with what if the situation can be held to test, understand and evaluate the best operating strategy using the computer software.
Most companies are familiar with traditional methods difficult to benefit from the management commitment required to implement lean manufacturing. This is because some aspects of the identified several areas, including procurement of raw materials, inventory management, labor management, and production control are hard to be changed. Refused to implement lean manufacturing based on improvement is because conventional thinking that still depend and get used to traditional methods compared for improvement method.
This is because some managers are insufficiently justified, and the lack of measurable evidence needed to persuade them to adopt lean (Detty et al, 2000). From some improvement by using the VSM can be evaluated with relatively modest effort, it is not as easy to do so in all cases. For example, predicting inventory levels throughout the production process is usually impossible with only a future state map, because with a static model cannot observe how inventory levels will vary for different scenarios (McDonald et al, 2002).
The used of simulation capable of generating resources requirements with performance statistics and the remaining flexible with the details of a particular organization. It can used to manage the uncertainty and create dynamic view of inventory levels, lead-times, and machine future land use map is different. This allows the quantification payback derived from using lean manufacturing principles, and their effect on the overall system. The information provided by the simulation can enable management to compare the expected performance fat-free system compared with the existing system designed to replace (Detty et al, 2000), and assume that this is significantly superior, it provides a convincing basis for adoption of lean.
There are lots of benefits why in implementing lean tool such as VSM required integration with simulation software. Based on Abdulmalek et al (2007) case study, where development of simulation model can help to contrast between CVSM and FVSM after improvement proposal. This has allowed managers to see the potential benefits using simulation in continuous production by result in reducing waste, better inventory, improve product quality and others. Additional benefits of simulation integrate with lean can be summarized in the point below:
Future VSM can generated with different response to the design propose and exploring several alternatives is easier with the helps of simulation.
Management can get a better comparison between the performance of the existing system and the suggested method by using simulation help, thus it convince management to adopt lean as an improvement (Abdulmalek et al, 2007).
Integration of discrete Event Simulation (DES) package with VSM can help organizations measure the expected advantages of lean manufacturing at the planning and evaluation stage (Detty et al, 2000).
The information that obtains from using DES package can be used as a benchmark to measure the effectiveness of implementing the lean transformation (Detty et al, 2000).
The system can be categorized between discrete or continuous. According to Jerry Blanks and his colleague, discrete system is when the state variable is changing only at a discrete set of point in time. Taking the banking system for example is a discrete system because of customer in the bank will only change when new customer arrived or when the service provided is complete. Meanwhile, the continuous system is when the state variable change continuously over time (Jerry Blanks et al, 2010). For example is production of crude oil in oil platform. So the usage of Discrete Event Simulation (DES) package for the lean improvement is suitable because can capture the process behavior as it develops over time and manufacturing that study is based on discrete system.
There is a lot of simulation software in the market that relate to the study propose. The name of a few well known software common among the analyst are Arena, Automod, Extend, Flexsim, MicroSaint, ProModel, Quest, SIMUL8 and Witness (Banks et al, 2004). All the simulation software has attained qualification for its purposes which translate to equal accuracy and effectiveness. The software only differs in term of its features and content and some differs to the fixture available. From amongst the regularly preferred simulation software, this study has chosen Witness or SIMUL8 as the model simulator. The reason behind the selection is because it is included and taught in the academic syllabus which will in turn ensure the validity of the produced result.
2.6 Reviews on previous case study
This is the summary and comparison of previous case study available that related to the study done. The review of previous case study would provide as a reference assistant in term of overall project construction. Beside, it is also can assist the project being done depart from the approach that has been approached before and thus can gain alternatives for solution method
.
2.6.4 Case Study 4
Title : Lean Manufacturing through Value Stream Mapping and Simulation
Author : Kuah Chuen Tse (2009)
Objectives : To develop a value stream map of the current situation of the photo printer Model X assembly department and develop improvement alternatives by using the simulation approach.
Methods : In this paper, three simulation models were built to compare three improvement alternatives for an assembly department. The improvement alternatives are pull system without line balancing, push system with line balancing, and pull system with line balancing. The key measurements used to evaluate the alternatives are value-added ratio, work-in-progress (WIP) level, work-in-queue level, time in queue, lead time, throughput, and number of operators. The effects of the alternatives were clearly demonstrated by the simulation
Conclusion : Current state VSM was developed to identify the wastes and possible improvement areas in the system. Improvement alternatives were developed and compared using simulation methodology. And lastly, a future state VSM was developed and the best alternative was selected and based on the selected alternative and simulation results.
Table 2.1 : The comparison of case study2.65 Comparison of Case Study
No
Author
Title
Objective
Conclusion
1
Fawaz A. Abdulmalek, Jayant Rajagopal, 2007.
Analyzing the benefits of lean manufacturing and value stream mapping via simulation: A process sector case study
To identify the benefit of implementing lean for application at the large integrated steel mill and develop desirable future state map.
The simulation model was developed by using System Modelling Corporation's Arena 5 software which shows the experiment improvements in selected performance measures were significant. The results shows that using a hybrid production system and TPM could potentially reduce the total production lead-time from its current value of 48 days to under 15 days, a reduction of almost 70% effect on lead-time.Meanwhile, the experiment revealed the WIP inventory of new system could potentially drive down the current average inventory level across all a reduction for almost 90%.
2
Yang-Hua Lian, Hendrik Van Landeghem, 2002.
An application of simulation and value stream mapping in lean manufacturing
To demonstrate the effect of lean using simulation at train manufacturing process line
By modifying the used of VSM by including four phase which shows the detail behaviour of production. It clearly helps to improve the situation with two simulation models are built for two respective scenarios, push and pull (Kanban) systems. The effects of lean can be clearly demonstrated by the simulation that reduce lead time, lower WIP inventory, increase value added ratio and solve the bottleneck problem.
3
Mohamed A. Shararah, Khaled S. El-Kilany, and Aziz E. El-Sayed, 2009.
Component Based Modelling and Simulation of Value Stream Mapping for Lean Production Systems.
To develop a tool combine the VSM with analysis using simulation. It is to ensure better decision for lean implementation at production of stamped steel steering bracket
The combination of VSM simulation software of Simulator using ExtendSim (VSMSx) has shown combination formed a powerful tool. By experimenting using VSMx software, it gives a good overview of interaction with the product. The experiment result shows that setup time, cycle time can affect the inventory of varying it. Beside the buffer size and batch size also can be altered to see how it affects the system. This has shown that the possibilities of simulation can pave the way towards better lean understanding by having good decision making with faster lean implementation.
4
Petter Solding, Per Gullander, 2009.
Concepts for simulation based value stream mapping
To present a concept of dynamic VSM of a system using simulation at Pressure Die Casting (PDC) plant. It is purposely to enable analysis of more complex system than standard VSM
The used of Simulation Based Value Stream Mapping (SBVSM) required builder to have skill in both. When experimenting with it can give information for future and possibilities . It result in showing how difference in lead time and how it relate to value added. The proposed future Kaizen then can be easily experiment by changing the setup times and cycle time.
5
Amr Mahfouz,
John Crowe and Amr Arisha, 2011.
Integrating Current State and Future State Value
Stream Mapping with Discrete Event Simulation: A
Lean Distribution Case Study
Using a tire distribution centre case study to develop a framework of discrete event simulation (DES) as an integration layer between current and future VSM.
In this research explain on current attention was directed into the use of simulation modelling in lean implementation and assessment processes due to many reasons. This research also based on a case study of their distributor and relates to supply chain. It need lean implementation to reduce cost and used of simulation to offers more thorough analysis of a system data including the examination of variability, the determination as to whether the data is homogenous, and the estimation of the probability distribution that fits the data patterns.
6
Charles R. Standridge, John H. Marvel, 2006.
Why lean needs simulation
To show how simulation can address the deficiencies towards lean improvement based on various industrial case studies.
This research explains the lean approach has deficiencies. These deficiencies include modelling and assessing the effects of variation, making use of all available data, validating the effects of proposed changes before implementation as well as identify other possible improvements, and assessing the interaction effects between system components. Various industrial applications are presented that show simulation was required to successfully address operational issues that lean approach failed to identify and could not resolve.
7
Chairat Thammatutto, 2011.
Improving Production Efficiency Through Lean Flexible Cellular Manufacturing Simulation
To develop, tested and implement a Lean Flexible Cellular Manufacturing Simulation to improve flexibility, efficiency and output. It is also to investigate the size of the batch and cellular manufacturing that can improve the flexibility, efficiency and output in the manufacturing system.
Three main steps in simulation methodology used in this study is conception, implementation and analysis. The conception phase is built to represent the real entity of the current system and use of lean to identify possible root causes of waste. In the implementation phase, the conception phase is transferred into the simulation model by using arena software to perform Discrete Event Simulation (DES) and use the Input Analyzer (IA) to perform the distribution fitting. Then final phase is analysis where the technique used is Design of Experiment (DOE). DOE is used as a decision making support tool and has brought a great impact in the analysis phase. The usage of Lean Flexible Cellular Manufacturing (LCFM) can be used to improve the efficiency of the manufacturing system. It can benefit not only to customers but also to the economy side. The WIP is reduced by 70% as a result of Lean Flexible Cellular Manufacturing.
8
Jon H Marvel, Charles R Standridge, 2009.
A simulation-enhanced lean design process
To do develop and enhance the process for lean system transformation that includes Kanban sizing, physical layout and parameters such as system performance.
The method used an integrated simulation modelling to validate the future value stream mapping (FVSM) into experiment lean transformation phase. By using lean that has been enhanced with validate the future value stream mapping (FVSM) using simulation modelling can ensure the FVSM is effectively addressing the current value stream mapping (CVSM) gap. The issue that usually overlooks in traditional lean can be considered its validation by using simulation models. Thus it can help proposed idea of FVSM to become legit to the real situation
9
Mohamed A. Shararah, Khaled S. El-Kilany and Aziz E. El-Sayed, 2011.
Value Stream Map Simulator Using ExtendSim
To develop a tool which combines with the designing tool of value stream maps with the analysis of the simulation model. This is to determine which decision for lean improvement is the best choice.
The method of this study is using software based on VSM that combine with simulation software. It is beginning by performing a component based modelling where it will act as reusable model. It is not feasible to develop a different kind of model for VSM for each production. It contains information such as the conceptualization of input, output and its entities. Before validate, Verification in this case is by testing a variety of settings of the input parameters and checking that the output is reasonable to use. Then it is validated and test it in extreme condition by adding work in progress for determining the level of confidence in the validation.
10
Kuah Chuen Tse, 2009.
Manufacturing through Value Stream Mapping and Simulation
To develop a value stream map of the current situation of the photo printer Model X assembly department and develop improvement alternatives by using the simulation approach.
In this paper, three simulation models were built to compare three improvement alternatives for an assembly department. The improvement alternatives are pull system without line balancing, push system with line balancing, and pull system with line balancing. The key measurements used to evaluate the alternatives are value-added ratio, work-in-progress (WIP) level, work-in-queue level, time in queue, lead time, throughput, and number of operators. The effects of the alternatives were clearly demonstrated by the simulation. As a conclusion, current state VSM was developed to identify the wastes and possible improvement areas in the system. Improvement alternatives were developed and compared using simulation methodology. And lastly, a future state VSM was developed and the best alternative was selected and based on the selected alternative and simulation results.
2.7 Conclusion
This chapter has provided a vital information required to enhance overall understanding of attempted techniques and methods. Other than that, review of previous case study also helps in defining project methodology in the next chapter. Last but not least, review of books, articles, journal and etc has largely assisted on the firm understanding basis for overall study direction.
