Lean Thinking and Methods - Kaizen
Kaizen, or rapid improvement processes, often is considered to be the "building block" of all lean production methods. Kaizen focuses on eliminating waste, improving productivity, and achieving sustained continual improvement in targeted activities and processes of an organization.
Lean production is founded on the idea of kaizen – or continual improvement. This philosophy implies that small, incremental changes routinely applied and sustained over a long period result in significant improvements. The kaizen strategy aims to involve workers from multiple functions and levels in the organization in working together to address a problem or improve a process. The team uses analytical techniques, such as value stream mapping and "the 5 whys", to identify opportunities quickly to eliminate waste in a targeted process or production area. The team works to implement chosen improvements rapidly (often within 72 hours of initiating the kaizen event), typically focusing on solutions that do not involve large capital outlays.
Periodic follow-up events aim to ensure that the improvements from the kaizen "blitz" are sustained over time. Kaizen can be used as an analytical method for implementing several other lean methods, including conversions to cellular manufacturing and just-in-time production systems.
Method and Implementation Approach
Rapid continual improvement processes typically require an organization to foster a culture where employees are empowered to identify and solve problems. Most organizations implementing kaizen-type improvement processes have established methods and ground rules that are well communicated in the organization and reinforced through training. The basic steps for implementing a kaizen "event" are outlined below, although organizations typically adapt and sequence these activities to work effectively in their unique circumstances.
Phase 1: Planning and Preparation. The first challenge is to identify an appropriate target area for a rapid improvement event. Such areas might include: areas with substantial work-in-progress; an administrative process or production area where significant bottlenecks or delays occur; areas where everything is a "mess" and/or quality or performance does not meet customer expectations; and/or areas that have significant market or financial impact (i.e., the most "value added" activities).
Once a suitable production process, administrative process, or area in a factory is selected, a more specific "waste elimination" problem within that area is chosen for the focus of the kaizen event ( i.e., the specific problem that needs improvement, such as lead time reduction, quality improvement, or production yield improvement). Once the problem area is chosen, managers typically assemble a cross-functional team of employees.
It is important for teams to involve workers from the targeted administrative or production process area, although individuals with "fresh perspectives" may sometimes supplement the team. Team members should all be familiar with the organization's rapid improvement process or receive training on it prior to the "event". Kaizen events are generally organized to last between one day and seven days, depending on the scale of the targeted process and problem. Team members are expected to shed most of their operational responsibilities during this period, so that they can focus on the kaizen event.
Phase 2: Implementation. The team first works to develop a clear understanding of the "current state" of the targeted process so that all team members have a similar understanding of the problem they are working to solve. Two techniques are commonly used to define the current state and identify manufacturing wastes:
- Five Whys. Toyota developed the practice of asking "why" five times and answering it each time to uncover the root cause of a problem. An example is shown below.
Repeating "Why" Five Times1
- Why did the machine stop?
There was an overload, and the fuse blew.
- Why was there an overload?
The bearing was not sufficiently lubricated.
- Why was it not lubricated sufficiently?
The lubrication pump was not pumping sufficiently.
- Why was it not pumping sufficiently?
The shaft of the pump was worn and rattling.
- Why was the shaft worn out?
There was no strainer attached, and metal scrap got in.
- Why did the machine stop?
- Value Stream Mapping. This technique involves flowcharting the steps, activities, material flows, communications, and other process elements that are involved with a process or transformation (e.g., transformation of raw materials into a finished product, completion of an administrative process). Value stream mapping helps an organization identify the non-value-adding elements in a targeted process. This technique is similar to process mapping, which is frequently used to support pollution prevention planning in organizations. In some cases, value stream mapping can be used in phase 1 to identify areas for which to target kaizen events.
During the kaizen event, it is typically necessary to collect information on the targeted process, such as measurements of overall product quality; scrap rate and source of scrap; a routing of products; total product distance traveled; total square feet occupied by necessary equipment; number and frequency of changeovers; source of bottlenecks; amount of work-in-progress; and amount of staffing for specific tasks. Team members are assigned specific roles for research and analysis. As more information is gathered, team members add detail to value stream maps of the process and conduct time studies of relevant operations (e.g., takt time, lead-time).
Once data is gathered, it is analyzed and assessed to find areas for improvement. Team members identify and record all observed waste, by asking what the goal of the process is and whether each step or element adds value towards meeting this goal. Once waste, or non-value added activity, is identified and measured, team members then brainstorm improvement options. Ideas are often tested on the shopfloor or in process "mock-ups". Ideas deemed most promising are selected and implemented. To fully realize the benefits of the kaizen event, team members should observe and record new cycle times, and calculate overall savings from eliminated waste, operator motion, part conveyance, square footage utilized, and throughput time.
Phase 3: Follow-up. A key part of a kaizen event is the follow-up activity that aims to ensure that improvements are sustained, and not just temporary. Following the kaizen event, team members routinely track key performance measures (i.e., metrics) to document the improvement gains. Metrics often include lead and cycle times, process defect rates, movement required, square footage utilized, although the metrics vary when the targeted process is an administrative process. Follow-up events are sometimes scheduled at 30 and 90-days following the initial kaizen event to assess performance and identify follow-up modifications that may be necessary to sustain the improvements. As part of this follow-up, personnel involved in the targeted process are tapped for feedback and suggestions. As discussed under the 5S method, visual feedback on process performance are often logged on scoreboards that are visible to all employees.
Implications for Environmental Performance
At its core, kaizen represents a process of continuous improvement that creates a sustained focus on eliminating all forms of waste from a targeted process. The resulting continual improvement culture and process is typically very similar to those sought under environmental management systems (EMS), ISO 14001, and pollution prevention programs. An advantage of kaizen is that it involves workers from multiple functions who may have a role in a given process, and strongly encourages them to participate in waste reduction activities. Workers close to a particular process often have suggestions and insights that can be tapped about ways to improve the process and reduce waste. Organizations have found, however, that it is often difficult to sustain employee involvement and commitment to continual improvement activities (e.g., P2, environmental management) that are not necessarily perceived to be directly related to core operations. In some cases, kaizen may provide a vehicle for engaging broad-based organizational participation in continual improvement activities that target, in part, physical wastes and environmental impacts.
Kaizen can be a powerful tool for uncovering hidden wastes or waste-generating activities and eliminating them. Kaizen focuses on waste elimination activities that optimize existing processes and that can be accomplished quickly without significant capital investment. This creates a higher likelihood of quick, sustained results.
- Potential Benefits:
- Potential Shortcomings:
- Failure to involve environmental personnel in a quick kaizen event can potentially result in changes that do not satisfy applicable environmental regulatory requirements (e.g., waste handling requirements, permitting requirements). Care should be taken to consult with environmental staff regarding changes made to environmentally sensitive processes.
- Failure to incorporate environmental considerations into kaizen can potentially result in solutions that do not consider inherent environmental risk associated with new processes. For example, an organization might select a change in process chemistry that addresses one improvement need (e.g., product quality, process cycle time) but that might be sub-optimal if the organization considered the material hazards or toxicity and the associated chemical and hazardous waste management obligations.
- By not explicitly incorporating environmental considerations into kaizen, valuable pollution prevention and sustainability opportunities may be disregarded. For example, an evident opportunity to conserve water resources may not be explored if water use is not expensive and therefore not considered a wasteful expense that needs to be addressed. Similarly, including environmental considerations in the kaizen event goals can lead to solutions that rely less on hazardous materials or that create less hazardous wastes.
Productivity Press Development Team. Kaizen for the Shopfloor (Portland, Oregon: Productivity Press, 2002).
Soltero, Conrad and Gregory Waldrip. "Using Kaizen to Reduce Waste and Prevent Pollution." Environmental Quality Management (Spring 2002), 23-37.
1 Joseph Romm. Lean and Clean Management: How to Boost Profits and Productivity by Reducing Pollution (New York: Kodansha America, 1994), 28.