By Issa Bass

Lean Manufacturing or TPS (Toyota Production System) is a management methodology originated from Japan and more often associated with Toyota Motor Company, It was introduce to the American public by James Womack and Daniel T. Jones in the 90’s.
It is about doing things right the first time and every time on a steady pace. It is also about reducing cycle time and inventory by eliminating waste. 
The underlying foundation of Lean manufacturing is the organizational strategy that constantly seeks a continuous improvement through the identification of the non-value added activities (Muda) and their elimination along with the reduction of the time it takes to perform the value added tasks.
The elimination of waste starts with the specification of the products value and then the identification of the value stream for each product. The value stream traces the production flow from raw materials to finished goods. In other words, the identification of all the processes of transformation through which the products have to pass until they reach the customers.
As in the case of the Theory Of Constraints, the purpose of implementing Lean is to increase Operating Profit, increase Cash Flow and Return On Investments.  To do so, Lean emphases the need to reduce waste, reduce inventory, reduce Cycle Time and set-up time. 
Let’s note that the definition of Inventory in the case of Lean is slightly different from TOC, it is the stock of goods that are ready to be transformed and the stock of finished products ready to be shipped to the customers.
The identification and elimination of waste is done through the following steps:

 1. Specify the exact value of each specific product.
The value of the products is determined by the customers through their desire to buy or not buy them and through the price they are willing to pay for them.

2. Identify the value stream for each product.
Each product is manufactured in a unique way. The value stream traces all the steps required to transform the raw materials into the products demanded by the customers.  Each step must add value to the product, in other words, the product must be worth more when it leaves a step in the process than when it got there. The analysis of the value stream is done for the sake of identifying waste and non value added steps and reducing the time necessary for the value added steps. Some non value added steps are necessary and inherent to the processes but some are unnecessary and cause clutter and can be sources of bottlenecks.

3. Make the value flow without interruptions.
To eliminate waste and clutter, the producer should put in place a production process that yields a steady and constant flow of products. So after the value of the products is determined, the value stream mapped, the clutters removed, the producer should strive to make the production flow relentless on a steady pace. Applying the One Piece Flow principle is one way of doing it and it will eventually lead to the Just-In-Time method: getting the right part, in the right quantity at the right time at every step of the process. A one- piece-flow process is only possible if all the steps take the same amount of time to process the materials before they send them to the next step.

4. Let the customer pull value from the producer.
When the materials flow on a steady and constant pace and the Just-in-Time principles are applied and are working, it becomes easier to predict and plan the work load executions and the deliveries since the time required for the completion of each task is known in advance. Inventory, cycle time, WIP (Work In Process) and complex scheduling are reduced, making it possible to let the customer pull the orders instead of building an excessive outbound stock of products waiting for a potential customer. An excessive stock of product in itself constitutes waste because one cannot know with certitude, how long it will stay unsold, and more money will be spent on its maintenance under the form of labor, warranty and the cost of the space it occupies. Letting the customer pull the products means only producing the products that are ordered by the customers. Let them determine what to produce, when and in what quantity.

5. Pursue perfection.
Opportunities for improvements will always be there, since continuous improvement does not end. Once the process flow has started, the company should keep seeking to uncover best practices. There are always possibilities to improve on existing processes by continuously setting higher targets. This in itself will prevent from falling back to old ways. Process improvements are made through kaizen events with the involvement of all concerned employees.

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TOC can be helpful since it is about identifying bottlenecks and improving them for a continuous improvement. The identification of the bottlenecks may require value stream and process mapping. Once the bottlenecks are identified, a Six Sigma project would be an effective tool to improve on them and TRIZ techniques can efficiently speed up contradiction resolutions and help save resources. By Issa Bass

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Just as in the case of process mapping, the purpose of value stream mapping is to visualize the chain of events that leads to the generation of a throughput in order to pin point a bottleneck, a clutter or opportunities for improvement. Yet it is necessary to distinguish Value Stream Mapping from Process mapping since a value stream is a chain of processes.  By Issa Bass

A Conversation with the Lean Expert -Jeffrey Liker
Jeffrey Liker is Professor of Industrial and Operations Engineering and the cofounder and Director of the Japan Technology Management Program at the University of Michigan.
I have been following his work in the field of Lean Manufacturing for many years and I have concluded that he is without a doubt one of its leading experts. His recent (must read) international best seller books “The Toyota Way” and its companion, “The Toyota Way Field Book” have proved that he is not only a great expert but also an excellent educator.
I have always been fascinated by his unique writing style. In these books, he mixes captivating and very instructive stories about important milestones in the history of Toyota Motor Company with very well circumscribed, straight-to-the-point analysis of the factors that made Toyota one of the most successful companies in the world.
The stories of the Lexus LS400 and the Prius in The Toyota Way are must reads for all business leaders and especially Project Managers. While telling how those two marvels came about, Jeff Liker shows how every step in their design fits in the overall Toyota philosophy.

 

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