Sustainable Manufacturing— The Lean Way

dhavas's picture

A recent buzz word in the manufacturing trade press is “Sustainable Manufacturing.” According to the U.S. Department of Commerce, Sustainable Manufacturing is defined as “the creation of manufactured products that use processes which minimize negative environmental impacts, conserve energy and natural resources, are safe for employees, communities, and consumers and are economically sound.” However, right now in this economy for many manufacturing companies the more significant issue is sustaining the business, period. Do you realize that implementing the Lean Manufacturing practices will not only help you sustain your company, but also minimize its negative environmental impacts?

“How is that true?” you ask.

When you undertake to implement Lean Manufacturing, you are going to be looking for 7 Kinds of waste; waste that when eliminated will conserve energy and material as well as reduce costs, free up cash and improve customer satisfaction. Those 7 kinds of waste are:

1) Excess Inventory – material or product for which there is not a customer demand or a downstream need. It takes up space, may spoil or become obsolete.

2) Over-production – making things faster than at the pace necessary to meet the customer demand or a downstream need. Over-production results in excess inventory.

3) Waiting – material, people or product waiting for the next operation, waiting for missing material waiting for a customer order. Waiting results in lower productivity for your employees and higher levels of Work-In-Process (WIP) and Finished Goods inventory.

4) Transport – movement of material and product that could be eliminated. Transport adds cycle time and uses energy.

5) Unnecessary Motion – actions required of the production people that can be eliminated. These actions place additional demands upon your employees and lower their productivity.

6) Defects – product that will require rework or be scraped. Defective material or product consumes materials, energy and your employee’s time.

7) Inappropriate Processing – operations that do not add to the value of the product. Excessive inspection, testing or recordkeeping often fall in this category and obviously add cost while consuming resources.

By implementing the Lean Manufacturing practices, you can reduce your costs and your inventory because you only build what is needed, when it is needed. You eliminate the energy and material used for building unnecessary inventory. You may be able to reduce your floor space requirements, saving the energy required to heat and cool this space  and the costs to maintain and insure this space also. These savings both reduce your operating costs and your impact on the environment. And, by reducing your inventory, you are no longer funding that inventory, making more cash available to your business.

 A perfectly Lean Manufacturing operation is simply stated, but not easy to achieve. To operate in a perfectly lean manner is to operate as follows:

Within a value stream, build what is needed only when it is needed in a batch size of one at a constant rate determined by customer demand with no time required to change setups between models.

 Let me explain what this brief statement means:

 A value stream – A value stream is the flow of information and material associated with a single product line from order desk to dock. A product line may have a number of models.

 What is needed only when it is needed – This is the “Pull System” of production and is often implemented using a “Kanban” system. A downstream operation informs an upstream operation when more material is needed. The upstream operation produces only the requested material for the downstream operation.

 In a batch size of one – Operating in this way, there is no inventory between operations as is the case when an operation makes a batch of material prior to passing the batch onto the next operation. Therefore, work-in-process (WIP) is not created and stored that cannot be immediately used.

 At a constant rate determined by customer demand – This is what is known as “Takt” time. It is calculated by taking the amount of material that must be produced in a shift, and dividing it by the planned productive hours in the shift. The material is produced at each step of an operation on this interval. Operations are often arranged in cells so that short term variations in the Takt time can be accomplished by changing the number of people manning a cell. Takt time changes that are beyond what can be accomplished with manning are accomplished by adding or removing cells.

It is important to note that to work “at a constant rate” requires that the equipment operate without fault during the production time and only good material be produced.

With no time to change setups between models – When every different model requires a unique setup, the lead-time to produce a given number of items using a lean operation is less than the time required using a traditional batch operation only when the setup time between models is reduced below some threshold value.


With a little thought, you see how operating in this way will reduce or eliminate the 7 forms of waste and their environmental impacts. But, Lean Manufacturing requires a focused effort and should not be undertaken lightly. Operating in a perfectly lean manner is not usually achieved immediately, but rather by continuously improving the operations and flow in a value stream over time. A strong commitment by the company management is needed in order to sustain the drive for change and to address the problems that arise. Nonetheless, the experience of numerous companies, who have successfully undertaken the challenge, has shown that Lean Manufacturing does contribute to sustaining your company and sustaining our environment.