The Seven Wastes of Lean Manufacturing and Their Impacts on the Environment
Lean manufacturing, a management philosophy primarily derived from the Toyota Production System, focuses on eliminating waste—called “Muda”— within a manufacturing system. It takes into account many kinds of waste, including the waste of excessive human motion, and aims to integrate each step of production into a holistic, efficient process that reduces cost and improves overall revenue. Under the lean manufacturing system, seven wastes are identified: overproduction, inventory, motion, defects, over-processing, waiting, and transport.
Overproduction
The most serious of the wastes, overproduction can cause all other types of wastes and results in excess inventory. Stocking too much of a product that goes unused has obvious costs: storage, wasted materials, and excessive capital tied up in useless inventory.
Depending, of course, on the product in question, overproduction can have very serious environmental effects. More raw materials than necessary are consumed; the product may spoil or become obsolete, which requires that it be tossed; and, if the product involves hazardous materials, more hazardous materials than necessary are wasted, resulting in extra emissions, extra costs of waste disposal, possible worker exposure, and potential environmental problems resulting from the waste itself.
Inventory
Inventory waste refers to the waste produced by unprocessed inventory. This includes the waste of storage, the waste of capital tied up in unprocessed inventory, the waste of transporting the inventory, the containers used to hold inventory, the lighting of the storage space, etc. Moreover, having excess inventory can hide the original wastes of producing said inventory.
The environmental impacts of inventory waste are packaging, deterioration or damage to work-in-process, additional materials to replace damaged or obsolete inventory, and the energy to light—as well as either heat or cool—inventory space.
Motion
Wasteful motion is all of the motion, whether by a person or a machine, that could be minimized. If excess motion is used to add value that could have been added by less, than that margin of motion is wasted. Motion could refer to anything from a worker bending over to pick something up on the factory floor to additional wear and tear on machines, resulting in capital depreciation that must be replaced.
There are many environmental costs from excess motion. One obvious one is the needless waste of materials used to replace worn machines; another one could be the health resources for overburdened employees, who might not have needed them if motion had been minimized.
Defects
Defects refer to a product deviating from the standards of its design or from the customer’s expectation. Defective products must be replaced; they require paperwork and human labor to process it; they might potentially lose customers; the resources put into the defective product are wasted because the product is not used. Moreover, a defective product implies waste at other levels that may have led to the defect to begin with; making a more efficient production system reduces defects and increases the resources needed to address them in the first place.
Environmental costs of defects are the raw materials consumed, the defective parts of the product requiring disposal or recycling (which wastes other resources involved in repurposing it), and the extra space required and increased energy use involved in dealing with the defects.
Over-processing
Over-processing refers to any component of the process of manufacture that is unnecessary. Painting an area that will never be seen or adding features that will not be used are examples of over-processing. Essentially, it refers to adding more value than the customer requires.
The environmental impact involves the excess of parts, labor, and raw materials consumed in production. Time, energy, and emissions are wasted when they are used to produce something that is unnecessary in a product; simplification and efficiency reduce these wastes and benefit the company and the environment.
Waiting
Waiting refers to wasted time because of slowed or halted production in one step of the production chain while a previous step is completed. To take the classic example, the production line, if one task along the chain takes longer than another, than any time the employee in charge of the next task spends waiting is wasted. The task that takes more time must be made more efficient, other employees must be hired to help, or the workflow must be better coordinated or scheduled in order to make up for this wasted time.
The environmental impact comes from the wasted labor and energy from lighting, heating, or cooling during the waiting period. Additionally, material can be spoiled, and components could be damaged because of an inefficient workflow.
Transport
Transport is moving materials from one position to another. The transport itself adds no value to the product, so minimizing these costs is essential. This means having one plant closer to another in the production chain, or minimizing the costs of transportation using more efficient methods. Resources and time are used in handling material, employing staff to operate transportation, training, implement safety precautions, and using extra space. Transport can also cause the waste of waiting, as one part of the production chain must wait for material to arrive.
Environmental costs to waiting include gas emissions, transportation packaging used, possible damage to the product en route, as well as a whole host of other wastes involving transporting hazardous materials.
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Sources:
EPA.gov “Lean and Environment Training Modules”
Lean Manufacturing Tools, “The Seven Wastes | 7 Mudas”
NASA.gov, “Lean for Government: Eliminating the Seven Wastes”