Lean Manufacturing grew out of the Toyota Production System or TPS. Today, Lean Manufacturing is most often referred to as Lean with its concepts and techniques being applied to many fields outside of manufacturing in sectors such as:
Lean Manufacturing roots go back to Henry Ford in the USA, but the techniques were developed and refined in Japan.
James Womack and colleagues brought these concepts back to the USA after studying the Toyota methods, then coined and popularized the term “Lean Manufacturing.” Lean is characterized by speed– better, cheaper and faster–and its’ focus on customer demand. By zeroing on what the customer wants and when he wants it, Lean teaches the wastefulness of excess inventories and their impact on responsiveness.
Toyota developed the system called “Just in Time” or JIT that provides for delivery of parts and components just at the time they are needed. JIT is applied internally to reduce work-in-process inventories and externally to reduce raw material inventories deliverd by suppliers.
Waste Elimination is the underlying principle of Lean. Waste is equivalent to non-value added activities. According to the Manufacturing Extension Partnership, 95% of an organization’s activities do not add any value to the product or service provided. By reducing or eliminating these non-value-adding wasteful activities, more time is spent on those activities that do provide a value-added benefit to the customer.
Eight types of waste are recognized that are generally present in most organizations:
- Excess Inventories: above and beyond what is needed
- Over-processing: putting more effort than is required
- Over-production: Making more product than is needed by the next operation or customer
- Transportation: moving the product in the plant or to the customer
- Excessive Worker Motions: unnecessary motions that add time and can cause injuries
- Defects/Errors: cause rejects and rework
- Waiting: for parts, deliveries, approvals, and
- Underutilized Workers: not using the full physical, emotional and intellectual capabilities of workers
The typical approach to eliminating waste is to decide on a product line family that shares the same operations or resources. All the activities (both value-added and non-value-added) are mapped in sequence. The characteristics of each operation are recorded such as cycle time and downtime. These series of activities is called a Value Stream and the map is called a Value Stream Map or VSM. After the Value Stream Map of the Current State is plotted, the team brainstorms the elimination of wastes that become apparent on the map and depicts a Future State that eliminates these wastes.
Kaizens (to-make-better) are concentrated improvement efforts that enable arriving at the Future State. In Japan, work groups often conduct these exercises on a daily basis looking for daily or “continuous” improvements of their processes. In the USA, it is more common to use a Kaizen Blitz in which a team devotes concentrated effort over a few days to obtain some of the improvements needed to arrive at the Future State.
These events could concentrate on material/information flow, inventory reduction and defects elimination. A 5S event is a special type of Kaizen that deals with Workplace Organization. 5S will be discussed in a later article.
Lean uses the eight wastes mentioned above as symptoms of the underlying root cause for the problems. For instance, excess inventories may be an indication of unbalanced workloads, machine breakdowns, misunderstood customer requirements, and unreliable suppliers.
As Lean has been adopted in other fields analogous examples of waste can be found.
- Patients waiting in the emergency room
- Large number of loan applications waiting to be processed
- Excess copies or blueprints
- Extra tests not contributing to diagnosis
- Designs including features not required
- Making more product than is needed or wanted
- Excessive trips to deliver prescriptions to in-patients
- Scheduling more face-to-face meetings than needed
Excessive Worker Motions
- Poor ergonomics
- Prescription errors
- Misreading blueprints
- For parts or components
- Searching for tools or documents
- Waiting for loan approvals
- Waiting for doctor prescriptions
- People watching a machine or each other work
- Not engaging employees in problem detection and solution
Being on the lookout for the evidence of waste provides a starting point for the investigation of the root causes and for finding solutions to the problems. Lean focuses on the customer and the organization’s performance in meeting the customer demand and customer quality requirements.