Value stream mapping is a method to create a structured image of the material and information flow on the shop floor. You often hear that a value stream map should be the first and last thing to do during a lean project. It sometimes sounds like all you need is VSM and Kaizen and you are on the road to success. This is bollocks! While value stream mapping is sometimes quite useful, it is not a universal tool.
A Bit of History
The idea of a structured diagram of the material flow in manufacturing was there long before Toyota and lean. A 1918 book Installing Efficiency Methods included diagrams very similar to modern value streams (Thanks, Bryan Lund and Michel Baudin for digging that and other details up).
At Toyota, it was called Material and Information Flow Analysis, or MIFA for short. Another name was MIFD for Material and Information Flow Diagrams. There it was used mainly at the internal lean consultancy group OCMS. From there it made its way into lean manufacturing.
The bible for value stream mapping in the Western world is the best-selling book Learning to See by Mike Rother and John Shook, published in 1999. They also coined the terms value stream mapping (VSM) and value stream design (VSD), and defined the most commonly used set of symbols in value stream mapping.
The modern Western view of value stream mapping stems from this book. However, it almost took on a life on its own, and in the Western world, VSM nowadays features much more prominently than the authors ever imagined, and sometimes even more than they wanted (more on that later).
Why Are Value Stream Maps so Popular?
About the Importance of Value Streams
Often, you hear that value stream maps are the beginning and the end of lean improvements, they are your alpha and your omega, they are your morning and your night, your ying and yang, your A and Z, your … This is bollocks!
The benefit of value streams are by far exaggerated in the Western world. At Toyota, in fact, they do very few value streams. They prefer to work directly on the shop floor.
While I like value streams and use them frequently, I personally find that the Western world puts too much emphasis on value stream mapping. Many invest too much time in making a value stream and then have no time or energy left to actually improve the situation on the shop floor.
I have seen companies where the bonus of the plant manager depended (among other things) on how often per year the plant updates its value stream. Once per year was lame, twice was acceptable, but only with four plant-wide value stream updates per year did the bonus start to look good. Hence, two to four times per year, all shop-floor-related management spent a day drawing value streams. They were rarely used for anything useful, except to improve the chances of a promotion for all involved. In my opinion, these value stream maps were a colossal waste of resources.
Again, value stream maps can be very useful if applied to the right problem. Doing them “just because” is a colossal waste of time!
Then Why Are Value Streams so Popular in the West?
At Toyota, improvements on the shop floor are done by people from the shop floor, and they know it very well. In the West, lean projects are often driven by external consultants. These consultants (hopefully) have a lot of experience in improvement projects, but chances are they have little knowledge of your products and know even less about how you make them.
Hence, they need to understand the shop floor first. However, imagine the consultant telling the client that during the first week of the project they’re not doing anything. They’ll only try to understand what the client knows already – how to make his products. Of course, the consultants still want to bill the client for the time they are doing nothing but learning to understand the client’s system. In all likelihood, the client would be less than impressed.
However, if the consultants tell the client that they start right away with a value stream, it already sounds much better (and much more billable). If the consultants tell the client that the value stream map is the most important thing for lean and cannot be skipped under any circumstances, it is so much easier to bill for the time and to get the support of the client to educate the consultants. Plus, in the end, the consultants even have a nice, fancy chart (the value stream map) to show the client.
Value stream maps are often pushed by consultants that need to familiarize themselves with the shop floor of their client.
Additionally, in Western companies, management often likes fancy slides and frilly charts. Value stream maps fulfill that desire. Yet, having a value stream map and improving the shop floor are not one and the same. Make sure the solution fits the problem. Besides, in my opinion, management rarely goes into the details of value stream mapping of somebody else, but rather treats it as a nice wallpaper.
So Does This Mean that Consultants Shouldn’t Do Value Streams?
Whoa, whoa, hold your horses. Do you really want a consultant fiddling with your shop floor without understanding what is really going on? Giving the consultants time to understand the shop floor is a necessity for a successful lean project! If they make a value stream map on the side, it does not hurt. Just remember that a value stream has a specific use but is not a tool to solve all problems.
However, if you merely want to bring outsiders up to date with your system, another possibility would be to give the consultants a boiler suit and have them work in the line for a day or two along with the normal operators. This also gives them a good understanding of the shop floor, possibly even more than a value stream map would. Although I imagine this may not be too popular with some consultants.
When to Use Value Stream Maps
The value stream map can give you a graphic representation of the information and material flow. This in turn can help you with both understanding and improving your shop floor organization.
When You SHOULD Draw a Value Stream Map
As with all lean improvement projects, you should first have a problem that you want to fix! Then, depending on the problem, you collect data, make different analyses, and use appropriate lean tools to improve your problem. A tool by itself is not a solution. Like many other lean tools, doing value stream mapping for the sake of doing the map won’t help you much.
A value stream map is a flow layout of the material and information flow. As such, it can help you visualize and understand the material and information flow. This can be done for the current state (also called value stream analysis or VSA) and also for the future desired state (also called value stream design or VSD).
As such, value stream maps can help you with understanding the flow of information and material. It can help you to see problems and inconsistencies. Common issues where value stream mapping is often useful are, for example:
- Designing a new manufacturing line (where it is part of the process)
- Improving the flow of material and information of an existing line in a flow shop (in comparison to a job shop)
- Determining lead times and replenishment times in flow shops (e.g., to calculate the number of kanban)
- Reducing unevenness (mura) in the material and information flow of flow shops
Please keep in mind that depending on the exact problem you try to solve, the maps can look differently. For example, if I want to determine the lead times, I count material. However, if I don’t need the inventories, it would be a waste to count them.
When You MAY Draw a Value Stream Map
For other problems, a value stream map may or may not help, depending on the details of your problem. Below are some examples of when a value stream map can be done somewhere during the improvement, but this is not necessarily clear at the beginning of the project.
- Capacity constraints
- Efficiency issues
- Finding and eliminating waste (helps you to find some, but also misses a lot. Not a perfect tool for waste elimination.)
- Cost issues
- Delivery performance problems
- Flow related problems in job shops, because the material flow is not standardized and may differ for every part. This makes a value stream map difficult to draw, and hence usually quite incomplete. You could focus on a more frequent high-value part, but this will still give you an incomplete picture. The more common parts you have, the more it makes sense to do a value stream map.
When You SHOULD PROBABLY NOT Draw a Value Stream Map
Value stream mapping is a useful tool. However, it is not a catch-all multi-purpose tool that solves all of your problem. Any issue not connected to the material or information flow is unlikely to benefit from a value stream map. Similarly, systems without a highly linear information and material flow usually do not benefit from drawing a value stream map either (for this, swim lane diagrams are more useful). Common examples of when a value stream map usually makes no sense are, for example:
- Safety issues
- Ingoing or outgoing quality problems
- Down times and breakdowns of machines
- A manager higher up wants a value stream (Okay, depending on the manager, this one may help your career, so you may move it up to the “definitely before anything else” category)
- Employee morale issues
- Supplier development
- Indirect areas, administrative areas, and support services, because they often have no structured flow. Swim lanes are much better here.
Again, get the right tools for the problem, not the other way around! Value stream maps have a lot of good uses, but they are not for every problem. Do a value stream map if you think it can help your particular problem, but not just because someone tells you to do it. In my next post Overview of Value Stream Mapping Symbols I will go through the value stream mapping symbols, including frequently found alternative versions. More posts discuss Basics of Value Stream Maps, and Practical Tips for Value Stream Mapping. In any case, I hope this was interesting and helpful to you. As always, I am looking forward for comments here or through social media. Now go out and organize your Industry!