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Lean and The Product Path Diagram

The great thing about lean is that there is always more to learn, there is always improvement in the thinking, the methodologies, the approaches, and the tools that get used. However, the underlying idea never changes, people somehow manage to complicate it when trying to explain what lean is and that perhaps is one of the things that make people think it is harder to achieve than it is.

Lean, when you boil it all down is about flow. It is about flowing only the product that you can sell through your processes in the shortest amount of time and at the best quality possible. If you can do that then your costs drop, you don't keep excess inventory, you don't make a Rolls Royce when the customer wants a Ford and you don't make 50 when they only want 5. That is the premise of lean, that is it, it's not complicated. The benefit of achieving this is that you free up resources and, importantly, cash all of which results in more money in the profit line.

Where things seem to get complicated is the how you go about creating that rapid flow through the business. There are almost more lean 'tools' than you can shake a stick at and that can make it harder than it needs to be. Fundamentally, if you can switch your head into thinking about flowing product through the business and that anything at all that stops it flowing is something you want to remove then you are at least 50% the way to solving any problem.

Get a Map

With any new journey it is good to have a map, so you know where you are going and what the stops are along the way and lean is the same. Historically the answer to the question, how do you build a lean map has been a Value Stream Map. These maps are very powerful and can highlight a whole host of options of things to fix and can show you the entire operation on one bit of paper.


Value Stream Mapping is a Team Sport

Value Stream Mapping is a fantastic lean tool for understanding what is really adds value in your organisations processes, doing it right then is critical, it takes a little time and needs some guidance but you can uncover a great deal about where the real problems lay in the business.

They are however a little complicated and if you have not done them then it can be a pretty daunting thing to do and it is bets to get a coach in to help you and the team. There is however another way to understand the flow of product through the organisation which is simpler and faster to do and in my opinion a lot more useful to most people. It is called the Product Path Diagram and it was the brainchild of Sean Fields and Michael Sanders in their new book Quantum Lean which is an absolute must read for anyone remotely interested in lean. Throughout the book Sean and Michael explain things in a manner that is easy to understand and engaging with lots of examples of things in the real world which is helpful. However, it was their discussion about the Product path that I really liked.

Unlike a Value stream map which has a multitude of different symbols and meanings the product path uses 3. The aim of the product path is to effectively map the flow of the product and map out where it goes and what it does, in each step we want to classify the action into only 1 of the 3 conditions which are represented on the diagram by 1 of the 3 symbols. The conditions:

  • Conversion – this is where the product is actually being worked on by either a person or a machine and is being converted from 1 state to another, i.e. you are adding bits on, taking bits off, drilling holes, you get the idea.
  • Non-Conversion – this is where you are still using resources either in people or machines / equipment, but you aren't transforming the product in anyway, typically you are moving the product, raw material or the person from one point to another as an example, inspecting things, doing rework and so forth.
  • Delay – this is when the product is just sitting there waiting, nothing is interacting with it, no people, no machines, it is just waiting.

Creating your Product Path Diagram

Creating the Product Path Diagram is easy, you just become the product, walk through the process, and go where the product goes. At every step decide if you are experiencing a Conversion, Non-Conversion or a Delay, as a hint if there are people or equipment involve then it's either conversion or non-conversion, if neither are there then it's always a delay! As you walk the process you want to capture roughly what is happening, what activity is being done and roughly how long it is taking, you are not timing the Olympic 100m sprint here, we do not care about fractions of a second or even, in most cases fractions of minutes. Just get the rough-cut numbers because they are going to be good enough, the most important thing is you get an accurate representation of the flow of the product journey.

I do not use the same symbols are Sean and Michael have in the book, I just popped off to the local stationary store and bought 2 different colour squares and some stars. The squares became the conversion and non-conversion and the stars become the delays in the diagram, they are easy to get, and you can move them around don the paper if you want to. Here is a section of one of the maps one of our clients did, that is right, after talking about the process for 45 minutes they went and mapped their whole product path diagram. Here is a segment of that total process.

Firstly, it visually jumps out what is conversion, that is the green square, the orange diamonds are non-conversions, and the gold stars are delays. Why gold stars? They are typically the quickest wins.

Here, the total process time is about 93 minutes for this process segment (remember it is rough numbers) to push out this batch, it was a batch of 4 so that means it is 23.25 minutes per unit but let us think about it as a batch just now. If we group things into our 3 categories: Conversion, Non-Conversion and Delay what we get is a startling result. For two thirds of the time in the process, the product is just sitting, waiting for something to happen, for just over a quarter of the time the product is being moved around, reworked, loaded, or unloaded. It is only being worked on 7% of the time, 93% of the time it is not moving forward in the process.

Get the Right Focus

Too often when companies look to improve things, they look at how they can make an operation quicker. They try to make the machines or process faster, they go out to buy a faster machine, ask people to work a little faster or put more people onto the operation. When really, where we should be focusing is on the other 93% of the time that is not converting the product in anyway.

Our client achieved an analysis of their product within 2 hours using the Product Path Diagram approach in a great simple, visual way that pointed them in the right areas to focus on in a way that you just wont get from a Value Stream Map, well, not quickly anyway. Within two hours we have a process-by-process analysis and a complete product Path drawing and a realisation of just how much unproductive time there was that could be reduced. Just think, if you could remove only 50% of the Non-Conversion or Delay time, in this process step that would be 43 minutes saved or avoided, you can't speed up the actual conversion process to get the same result, what you could do it make quit a bit more of the product with all that extra time, if your customer needs them.

Ready To Start Your Lean Journey?

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Ready To Start Your Lean Journey?

Make a booking now and find out how we can help you Make Things, Better


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Wednesday, 04 August 2021

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