When Continuous Flow of Product in a Facility is Restricted the Option is to Use
VALUE STREAM MAPPING
மதன் குமார் கி Madhan Kumar K
மதன் குமார் கி Madhan Kumar K
Manufacturing Excellence Manager (TPM, Lean Manufacturing and Six sigma Expert) @Britannia
"Whenever there is a product for a customer, there is a value stream. The Challenge lies in seeing it."
What is Value Stream Mapping?
"Value Stream" may be a new phrase in your vocabulary. A Value Stream is all the actions (both value added and non value added) currently required to bring a product through the main flows essential to every product.
- the production flow from raw material into the arms of customer, and
- the design flow from the concept to launch.
This looks at the production flow from customer demand back through raw material, which is the flow we usually relate the lean manufacturing and precisely the area where many have struggled to implement lean methods.
Taking a value stream perspective means working on the big picture, not just individual processes; and improving the whole, not just optimizing the parts. If you truly look at the whole and go all the way from molecules into arms of the customer, your will need to follow the value stream product across many firms and even more facilities. But mapping this entire stream is too much for getting started. This page covers the "door-to-door" production flow inside a plant, including shipment to the plant's customer delivery of the supplied parts and material, where you can design a future state vision and start implementing it right way. This is a good level at which you begin your mapping and implementing effort.
Value Stream mapping is a pencil and paper tool that helps you to see and understand the flow of material and information as a product makes its way through value stream. What we mean by value stream mapping is simple: follow a product's production path from customer to supplier and carefully draws a visual representation of every process in the material and information flow. Then ask a set of key questions and draw the future state map of how value should flow.
WHY VALUE STREAM MAPPING IS AN ESSENTIAL TOOL?
- It helps you visualize more than just the single process level, i.e. assembly, welding, etc., in production. You can see the flow.
- It helps you see more than waste. Mapping helps you see the sources of waste in your value stream.
- I provides a common language for talking about manufacturing process
- It make decisions about the flow apparent, so you can discuss them. Otherwise, many details and decisions on your shop floor just happen by default.
- It ties together lean concepts and techniques, which helps you avoid "cherry picking"
- It forms the basis of an implementation plan. By helping you design how the whole door-to-door flow should operate--a missing piece in so many lean efforts--value stream maps become a blueprint for lean implementation. Imagine trying to build a house without a blueprint.
- It show the linkage between the information flow and a material flow. No other tool does this.
- It is much more useful than quantitative tools and layout diagrams that produce a tally of non-value added steps, lead time, distance traveled the amount of inventory and so on. Value Stream mapping is a quantitative tool by which you describe in detail how your facility should operate in order to create flow. Numbers are good for creating a sense of urgency or as before/after measures. Value stream mapping is good for describing what you are actually going to do to affect those numbers.
Drawing Current State Map:
Developing a future state begins with the analysis of the current production situation. This section shows how to create a current state map using a simple A3 paper & a pencil. Mapping begins at the level of door-to-door flow in your plant, where you draw process categories like "assembly"or "welding", instead of recording each processing step.
Once you see the overall flow through the plant, you can change the level of magnification; zooming in to map every individual step within a process category, or zooming out to encompass the value stream external to your plant.
As you map the current state, it is important to evaluate the processes with the creation of a future state in mind. It is necessary to understand what you want to achieve when you get "lean" in order to know what the current obstacles are.There may be several goals that you would like to achieve with your lean effort. Here are a few of the higher-level objectives that are typical characteristics of a lean value stream. For your initial efforts in creating a connected value stream, these should be your primary objectives. Subsequent activities can focus on more specific point kaizen improvements and continued elimination of waste.
1. Flexible processes to respond quickly to changing customer requirements, especially increased variety of products. Is the process capable of producing any part at any time?
2. Short lead-time from customer order to completion and delivery of the product.
3. Connected processes with continuous flow and pull of materials.
4. Each value stream may have separate "flow loops" within the value stream that are identified by points when flow is not possible. These are dictated by the current process limitations.
5. Simplified information flow within the value stream that comes from internal customers (the following process).
6. Aclear awareness of the customer requirement (the "voice of the customer"). In a pull environment, the customer (next operation) dictates what is done and when. The voice of the customer should provide:
a. Required rate (takt time)
b. Required volume (quantity)
c. Required model mix
d. Required sequence of production
7. Every value stream and flow loop within the value stream will have a "pacesetter" process that will establish the rate (per takt time) for all other opertions.
Symbols used to create the Value stream mapping is show in the below figure.
After completion of current state map the view looks as shown in the below fig.
The Future-State Map:
The purpose of current state value stream mapping is to identify/highlight the sources of waste and eliminating them by implementation of a future state value stream that can become a reality within a short period of time. The goal is to build a chain of production where the individual processes are linked to their customer(s) either by continuous flow or pull and each process gets as close as possible to producing only what is customer need when they need it.
Key Questions to draw a future state map:
- What is the takt time based on the available working time of your down stream process that are closest to the customer?
Or Takt time = Total available time /customer demand time/nos.
- Will you build to a finished goods supermarket from which the customer pulls, or directly to shipping?(The answer to this question depends on several factors such as customer buying partners, reliability of your process, and the characteristics of your product. Building directly to shipping will require either reliable, short-lead-time, order-to-delivery stream, or more safety stock. Fortunately, your order-to-delivery lead time involves only those processes from the pacemaker process downstream to delivery)
- Where you can use continuous flow process?
- Where will you need to use supermarket pull systems in order to control production upstream process?
- At what single point in the production chain(the "pacemaker process") will you schedule production? ( Remember that all material transfers downstream of the pacemaker process need to occur as flow)
- How will you level the production mix at the pacemaker process?
- What increment of work will you consistently release and take away at the pacemaker process?
- What improvements will be necessary for the value stream to flow as your future state design specifies? (This is the place to note any equipment and procedural improvements that will be necessary, such as reducing changeover time or improving machine uptime. We use the kaizen lightning burst icon to indicate these points in the process)
Complete Future State Value Stream Map is shown in the fig below:
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Source: https://www.linkedin.com/pulse/value-stream-mapping-madhan-kumar-k
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