Value stream mapping is a powerful tool to the lean and also to the Six Sigma practitioners nowadays. It helps to visualize the whole system more than the single process level; individual can see the flow of both the materials & information. In textile and RMG sectors, how value flows from ‘order placement’ to ‘delivery’ the goods on customer’s hand can be visualized by seeing the value stream map. And how can we manage the processes in a better way than the current system that also can be derived from analyzing present state map. It is the beginning of the journey to continuous improvement.
The rule of change:
“It is not necessary to change, survival is not mandatory.”¹ It’s simple. The world market is like the galaxy. You know, our galaxy is expanding all the time, so being our business markets. Same law powered by the nature, fashioned by the leader, catalyzed by the behavior of the people and many more parameters. What do you expect?
The time you are reading this, it’s unique and it’s just gone. I am sorry for that. If you think that you are successful and it will remain still, you are wrong. Success is a product of continuity of what you were and what you are. It’s just the difference between two time fraction; not a constant. So, my point is “it’s time to change”. Yeah, I am talking about the textile and RMG markets of Bangladesh.
What is Value Stream Mapping (VSM)
Value stream mapping is a visual tool to map the set of all courses of actions to bringing a product to the end users through three critical measurement tasks.
- Problem solving task is the task to run from concept through detailed design and engineering to production launch.
- Information management task is to run from order taking through detailed scheduling to delivery.
- Physical transformation task is to proceed from raw materials to a finished product in the hands of the customer.
If managers are asked about their integrated business functions, most of them can’t answer that. You are thinking why you need to know all of that? Let me tell you why. ‘Whenever there is product for a customer, there is a value stream, and the challenge lies in seeing it’3. You can’t see the whole and so you can’t see the holes.
To understand how value stream can be able to benefit you, before that we have to know a little bit of finance. Taichiiohno in his “workplace management” book, give a theory of making profit in business. There are mainly three ways to earn profit.
- Price – Cost = Profit
- Profit = Price – Cost
- Price = Cost + Profit
Yeah, you know algebra well. They are all the same. But Taichiiohno begs that they are not the same. Let’s start with the last one. Here the profit is set first and after that the cost, then the price been given. Basically government uses this pricing strategy. Second one is a little bit different. This strategy is for the luxury goods where cost can’t be minimized. Then price is set later. The first one meant to be that the price is set by the market. And if you have to survive you have to minimize the cost. And that is I am talking about while it’s the textiles and RMG industries.
Value stream mapping helps you to visualize all the process from ‘call’ to ‘cash’ and shows you where you can cut cost. Basically there are three kinds of activities
- Value added (VA)
- Non value added but unavoidable (NVA)
- Non value added and avoidable (waste)
Here a generalized format that is divided into following three parts
- Understanding product families
- Designing the present state map
- Designing the future state map
1. Understanding product families
2. Designing the present state map
A. Takt time calculations: Takt time is the pace or rhythm or heart bit of production. In Lean, takt time is the rate at which a finished product needs to be completed in order to meet customer demand.
Table 1: Takt time calculation
B. Process path design: every process and their precursors are found out first.
Here the cycle time(C/T) is divided into two parts Manual time and automatic time. Manual is the cycle time that is done by operator himself and automatic time is the time needed by machines to complete the each process once. Defect rate is the rate of defects that is expressed in percentage. The changeover time is the time needed to changeover a style, changeover after shift break etc. Uptime is the availability of the machines. Machine need to stop for various reasons time to time. Uptime is the percentage of how much time the machine is available. It is also expressed in percentage.
From inventory data table, the input and output inventory amount and DOS (days of supply) is deducted. DOS is the ratio of “amounts on hand” to “daily demand”. At last the process path is designed with timeline. In timeline there is two time mentioned. One is DOS (Days of supply) that indicate the level of inventory and how much time is needed to consume the inventory. And another is C/T (cycle time). Then the process lead time (PL/T) is deducted by adding all the DOS time and Value added time (VA/T) is deducted by summing up all the cycle time (C/T).
From the information of figure 2 we can calculate the Process Cycle Efiiciency (PCE). It indicates how efficiency is your process cycle.
C. Designing the present state map
A complete present state map shows both the physical flow and the information flow. Three type of information is needed to run a process.
b) Information between the suppliers and the production control team
c) Information between the facility process and the production control team
After all the information get the information web is also need to be included to get the final present state map. Present state map like figure 3 is the blueprint to Present state map like figure 3 is the blueprint to visualize the whole process.
3. Designing the Future state map
From the present state map one can visualize the total value chains of a product from idea generation to delivery. Future state map is the modified version of the present state map. It’s an art to design and see the whole value stream. There are many tools available to improve the production process, cut cost, reduce non value added activity (Muda), reduce unevenness (Mura), reduce overburdening (Muri) in Lean principle. Such as supermarket system, measure overall equipment effectivesness (OEE), heijunka, Just in time (JIT), FIFO (Fast in fast out), LIFO (Last in fast out), standard minute changeover, reducing the bullwhip effect, kaizen, kanban, jidoka etc.
Most of all 9 questions should be raised while designing the future state map. They are-
- Where can we balance cycle times (C/T) with talk time?
- Where can we connect process through one piece flow?
- Where must we pull with Kanban (A system to reduce inventory cost and ensure smooth production flow). to maintain flow?
- Will we pull sequentially or based on replenishment?
- Where will we schedule production pacemaker?
- How will we level the mix and volume of production (heijunka)?
- Where can we use automation (jidoka)?
- We must study the current state for which process have losses and must be improved?
- What to do, when to do, whom to delegate?
Value stream mapping is the door to walk ahead to the journey of lean. Where lean is all about respecting people while eliminating the 3 M’s which are muri (overburdening), mura (unevenness), and muda (non value added activity). Sadly, respecting people is often left out which turns lean manufacturing into mean manufacturing.
 Dr Edward Deming
 The Machine that Changed the World, Womack and Jones
 Learning to see, Lean Enterprise institute, Mike Rother& John Shook
 Lean thinking, Womack and Jones
 The introduction to lean six sigma approach, MIT open courseware
 Adapting lean Manufacturing principles to the textile industry, Kelly Ann Goforth
 Workplace management, TaichiiOhno