Lean Manufacturing Defined
Lean manufacturing is a systematic framework for eliminating waste from a manufacturing system, or value stream, without sacrificing productivity. The value stream comprises all of the activity and information streams that exist between the raw material supplier and the possession of the customer. Lean is about empowering people at all levels of an organization to identify and eliminate waste in order to continuously increase the value delivered to customers.
A lean mentality and culture adds value and reduces activities that decrease value. Put simply, lean manufacturing aims to create more value for customers while reducing waste.
The 8 Wastes of Lean
In lean, “value” is defined as any action or process that a customer would be willing to pay for. Meanwhile, “waste” is defined as anything that doesn’t add value to a product, or cost without benefit. Lean practitioners commonly agree on 7 wastes, which are derived from the Just in Time mentality to reduce costs and increase value:
• Overproduction: producing more, sooner, or faster than is required by the next process or customer
• Waiting: operators standing idle while machines cycle, equipment fails, parts delay, etc.
• Transport (or conveyance): movement of parts and products beyond the absolute minimum necessary
• Overprocessing: unnecessary or incorrect processing
• Inventory: keeping more than the minimum stock of raw materials, parts, work in process (WIP), and finished goods necessary.
• Motion: movements made by operators or machines beyond what is necessary
• Defects: time and effort spent correcting and inspecting rework and scrap
Some practitioners include an 8th waste: unutilized talent. While the first 7 wastes are directly related to manufacturing processes, the waste of unutilized talent is specific to manufacturing management. Remember that lean is focused on humans; without humans, there is no lean culture.
The Lean Manufacturing Cycle
The Lean Enterprise Institute lays out a 5-step cycle for implementing lean:
- Specify value from the standpoint of the end customer by product family.
- Identify all the steps in the value stream for each product family, eliminating whenever possible those steps that do not create value.
- Make the value-creating steps occur in tight sequence so the product will flow smoothly toward the customer.
- As flow is introduced, let customers pull value from the next upstream activity.
- As value is specified, value streams are identified, wasted steps are removed, and flow and pull are introduced, begin the process again and continue it until a state of perfection is reached in which perfect value is created with no waste.
Thinking With Lean Philosophy
To accomplish this goal, organizations implement lean thinking both in their management and production philosophies. According to the Lean Enterprise Institute, “lean thinking changes the focus of management from optimizing separate technologies, assets, and vertical departments to optimizing the flow of products and services through entire value streams that flow horizontally across technologies, assets, and departments to customers.”
Lean manufacturing is a continuously evolving effort that requires understanding and participation from all levels of an organization. Just as important to achieving a lean operation as the technical implementation is lean thinking. There are a variety of strategies for reducing waste in a production process, but it is also important to understand and internalize the underlying philosophies in order to sustain a lean operation and continue to strive toward a perfect, zero-waste operation.