Normal distribution is a statistical representation where most distributions that are observed are relatively close to one mean (average). If there is deviation associated with the mean, which there normally is, the deviation remains almost identical on the plus side as the deviation on the minus side. When normal distribution is graphed (histogram) it generally takes the shape of a bell showing "normal" or even distribution from the mean.
The term supermarket or grocery store in lean six sigma refers to a predetermined market (storage/inventory). The supermarket carries the necessary "supplies" for a work area that is close by. When a customer (internal/external) needs an item they can retrieve the item from the supermarket. The supermarket then replenishes or restocks their supplies based on the downstream demand. Supermarkets prevent overstocking and help lower inventory levels.
Special Causes of Variation is when something happens to cause a variation in the output (Y) that is unusual and is not consistent or constant. Special causes of variation are often referred to as assignable causes because they can be eliminated with a response or a solution to individual variations. Control Charts can be used to differentiate between common causes and special causes of variation.
Example: In the photo above three arrows hit the target dead center. One arrow hit the target high and to the left. The arrow that landed high and to the left is an example of a special cause of variation.
Setup Reduction refers to a decrease in the changeover time. The setup reduction attempts to reduce every possible second from the changeover or setup time. Because the changeover or setup is not transforming any materials or services that a customer has agreed to pay for, both setup and changeover can be considered a form of waste/muda. In most cases a setup reduction can reduce the setup time by 50% or more.
The ©REDUCE methodology by Lean Strategies International LLC is a systematic way of reducing both setup and changeover times. For more information on the ©Reduce Methodology visit our recent blog post on Listen to the Gemba, Changing things around.
Mixed-Model Production is the practice of making, assembling or producing several different parts or products (this can also be applicable to services) in varying lot sizes so that the organization produces close to the same mix of products/services that will be sold on the same day. The goal of a mixed-model production tactic is to smooth out the demand of upstream workcenters, cells, suppliers and vendors which results in a reduced inventory, faster changeovers and more accurate replenishment of products ultimately working towards building and or producing in accordance with daily demand.
The purpose of Lean Accounting is to support the lean enterprise as a business strategy. It seeks to move from traditional accounting methods to a system that measures and motivates excellent business practices in the lean enterprise. Applying Lean principles is part of this system.
The Vision for Lean Accounting
Ref: Wikepedia, Lean accounting
A lead time ladder is the timeline shown on the bottom of a value stream map. The lead time ladder is used to calculate the production lead time.
Kaizen is the Japanese term for continual improvement. Another way of defining Kaizen is a Japanese philosophy of continuous improvement of working practices, personal efficiency, etc. Literally translated kaizen means, change for the better.
The House of Quality, is a diagram whose structure resembles that of a house. The tool aids in determining how a product/service is living up to customer defined attributes. Although quite intricate, it is capable of storing a lot of information and comparing large amounts of data used for defining the relationship between customer desires and the firm/product capabilities. The house of quality works through a six step process:
The house of quality is part of the quality function deployment (QFD) process and forces engineers, designers and developers to think about customer needs. The house also helps teams in creating a crossfunctional design so that probelms are not built into a new service or part.
External setup time is the amount of time associated with the elements or activities of a setup procedure that are performed while the machine is running. The terminology comes from the fact that these activities are done outside of or away from the machine, or external to the process.
Engineering change orders (ECO) are used for changes in components, assemblies, or documents such as processes and work instructions. They may also be used for changes in specifications.
The control chart is a graphical comparison of process performance that is used to study how a process might vary over time. The control chart usually will include predetermined control limits which are shown as the UCL (upper control limit) and the LCL (lower control limit). The control chart also shows a "mean" or average line which is based on historical data. The control charts primary purpose is to show a comparison of the current data to the historical data that is plotted on the chart. Doing this helps the user see whether the variation in a process is consistent (controlled) or the process has random variation (out of control, also referred to as special causes of variation).
When should you use a control chart?
Using a Control Chart:
1. Select the appropriate control chart: variables - X chart, R Chart, σ chart Attributes - p chart, np chart, c chart.
2. Establish the time period that you will be collecting data for.
3. Collect data
4. Analyze data looking for "out of control" signals.
5. Work to find the root cause of any "out of control" signals.
Concurrent engineering is a concept which refers to the simultaneous engineering or participation of all functional departments in the product or service development and design. This activity normally includes suppliers and customers in the design process too. Concurrent engineering decreases the amount of time it takes to develop products and services and reinforces the importance of crossfunctional design. Concurrent engineering also ensures that the final design does in fact meet the needs of stakeholders, customers and helps to minimize costs while maximizing the quality.
For more information check out these books:
Common causes of variation are the causes of variation that are inherent in a process over time. Some degree of variation will naturally occur in every process these are the common cause variations. These types of variation generally effect all outputs (Y's) of a process.
The boundaries/scope of a charter make it clear to the team what the starting and stopping point are and to what level. The scope includes lateral and longitudinal scope. Starting and stopping points are usually outlined with a SIPOC map or a flow chart. Scope sets the in’s and out’s or the boundaries for team members.
The goal statement identifies goals, objectives or targets that the team is trying to achieve once the project is completed.
The Goal is to reduce the cash to cash cycle time by 50% resulting in a reduced, cash to cash cycle of 15 days.
The Goal is to (improve or reduce) the (problem) by (metric,category) resulting in a (improved or reduced)(category) of (metric).
Andon is a japanese term that refers to a system of notification which is widely used today. The system provides management, maintenance or other employees of a quality issue, line stop or process problem. The andon system utilizes sensory notifications to alert others of a problem and more importantly the need for support. The alerts are are normally activated manually by a worker who observes the issue or by automated means that senses an abnormality somewhere in the process.
A data box is a box drawn on a value stream map to illustrate and show data that is related to the process on the value stream map. Some types of data that are commonly held within a data box are:
A process by which products are designed with ease of assembly in mind. If a product contains fewer parts it will take less time to assemble, thereby reducing assembly costs. In addition, if the parts are provided with features which make it easier to grasp, move, orient and insert them, this will also reduce assembly time and assembly costs. The reduction of the number of parts in an assembly has the added benefit of generally reducing the total cost of parts in the assembly. This is usually where the major cost benefits of the application of design for assembly occur.
Demand stability refers to the reduction of variation that happens with supply and demand.
Design for manufacturability is the process of designing products to optimize manufacturing functions such as fabrication, assembly and test. DFM focuses on the simplification of parts, products and processes to improve quality and reduce manufacturing costs.
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