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Muda

Muda

MUDA (無駄) is a Japanese term for anything that is wasteful and doesn't add value. It is also a key component of the Toyota Production System. The Toyota Production System has its genesis in the elimination of waste. In any case waste reduction is clearly an effective way to increase profitability. A process adds value by producing a good or providing a service. A process also consumes resouces, waste is when more resouces are consumed than are necessary to produce the good or provide the service. "The seven wastes" identify and classify resources, commonly wasted. These "seven wastes" were formally identified by Toyota’s Chief Engineer, Taiichi Ohno, as the focus of the Toyota Production System. Since that time one additional waste has been added to the list. MUDA can be classified as follows:

Defects

Quality defects prevent the customer from accepting the product produced. New processes must be added in an effort to reclaim some value for the otherwise scrap product.

Overproduction

Overproduction is to produce/acquire an item before it is actually required.

Transportation

Movement of the product. Each time the product is moved it stands the risk of being damaged, lost, delayed, etc.

Waiting

Refers to both the time spent by the works waiting for resouces to arrive, the queue for their products to empty as well as the capital sunk in goods and services that are not yet delivered to the customer.

Inventory

Work-In-Progress (WIP) represents a capital outlay that has not yet produced an income either by the producer or by the consumer.

Motion

As compared to Transportation, Motion refers to the producer or worker. This has significance to damage, wear, safety. It also includes the fixed assets, and expenses incurred in the production process.

Overprocessing

Using a more expensive or otherwise valuable resource than is needed for the task. There is a particular problem with this item as regarding people. People may need to perform tasks that they are over qualified for so as to maintain their competency. This training cost can be used to offset the waste associated with overprocessing.

Skill

Organizations employ their staff for specific skills that they may have. These employees have other skills, it is wasteful to not take advantage of these skills as well. "It is only by capitalizing on employees' creativity that organizations can eliminate the other seven wastes and continuously improve their performance."

External links

http://www.emsstrategies.com/dm090203article2.html

Toyota Production System

The Toyota Production System (TPS) (トヨタ生産方式) is the framework and philosophy organizing the manufacturing facilities at Toyota and the interaction of these facilities with the suppliers and customers. It was largely created by three men: the founder of Toyota, Sakichi Toyoda, his son Kiichiro Toyoda, and engineer Taiichi Ohno. The main goal of the TPS is to eliminate waste (無駄, Muda). There are 7 kinds of waste targeted in the TPS. # Defects # Overproduction # Transportation # Waiting # Inventory # Motion # Overprocessing Toyota was able to greatly reduce cost and inventory using the TPS, enabling it to become one of the three largest companies in the world. Due to this stellar success of the production philosophy many of these methods have been copied by other manufacturing companies.

Commonly used terminology in TPS:

- Just In Time (ジャストインタイム) (JIT)
- Kanban (看板, also かんばん) (engl.: Sign, Index Card)
- Muda (無駄, also ムダ) (engl.: Waste)
- Heijunka (平準化) (engl.: Production Smoothing)
- Andon (アンドン) (engl.: Signboard)
- Poka-yoke (ポカヨケ) (engl.: fail-safing - to avoid (yokeru) inadvertent errors (poka))
- Jidoka (自働化) (engl.: Autonomation - automation with human intelligence)
- Kaizen (改善) (engl.: Continuous Improvement)

References

- Taiichi Ohno: Toyota Production System: Beyond Large-scale Production, Productivity Press Inc., 1995, ISBN 0915299143.
- Yasuhiro Monden: Toyota Production System, An Integrated Approach to Just-In-Time, Third edition, Engineering Management Press, 1997.
- Jeffrey Liker: The Toyota Way: 14 Management Principles from the World's Greatest Manufacturer, First edition, McGraw-Hill, 2003, ISBN 0071392319.
- James P. Womack, Daniel T. Jones: Lean Thinking: Banish Waste and Create Wealth in Your Corporation, Revised and Updated, HarperBusiness, 2003, ISBN 0060974176.
- James P. Womack, Daniel T. Jones, Daniel Roos: The Machine That Changed the World: The Story of Lean Production, HarperBusiness, 2003, ISBN 0060974176.
- Shigeo Shingo: A Study of the Toyota Production System, Productivity Press, 1981 (Japanese), 1989 (English), ISBN 0915299178.

External links

- [http://www.toyotageorgetown.com/history.asp History of the TPS at the Toyota Motor Manufacturing Kentucky Site] ja:トヨタ生産方式 Category:Production and manufacturing Category:Quality

Electric polarity

Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interactions. Electrically charged matter is influenced by, and produces, electromagnetic fields. The interaction between charge and field is the source of one of the four fundamental forces, the electromagnetic force.

Overview

Electric charge is a characteristic of subatomic particles, and is quantized. For example, electrons have a charge, by convention, of −1. Protons have the opposite charge of +1. Quarks have a fractional charge of −1/3 or +2/3. The antiparticle equivalents of these have the opposite charge. There are other charged particles. The SI unit of electric charge is the coulomb, which represents approximately 6.24 x 10¹⁸ elementary charges (the charge on a single electron or proton). The coulomb is defined as the quantity of charge that has passed through the cross-section of a conductor carrying one ampere within one second. The symbol Q is used to denote a quantity of electric charge. Electric charge can be directly measured with an electrometer. The discrete nature of electric charge was demonstrated by Robert Millikan in his oil-drop experiment. Formally, a measure of charge should be a multiple of the elementary charge e (charge is quantized), but since it is an average, macroscopic quantity, many orders of magnitude larger than a single elementary charge, it can effectively take on any real value.

History

As reported by the Ancient Greek philosopher Thales of Miletus around 600 BC, charge (or electricity) could be accumulated by rubbing fur on various substances, such as amber. The Greeks noted that the charged amber buttons could attract light objects such as hair. They also noted that if they rubbed the amber for long enough, they could even get a spark to jump. This property derives from the triboelectric effect. The word electricity derives from ηλεκτρον (electron), the Greek word for amber. C. F. Du Fay proposed in 1733 [http://www.sparkmuseum.com/BOOK_DUFAY.HTM] that electricity came in two varieties which cancelled each other, and expressed this in terms of a two-fluid theory. When glass was rubbed with silk, DuFay said that the glass was charged with vitreous electricity, and when amber was rubbed with fur, the amber was said to be charged with resinous electricity. By the 18th century, the study of electricity had become popular. One of the foremost experts was Benjamin Franklin, who argued in favor of a one-fluid theory of electricity. Franklin imagined electricity as being a type of invisible fluid present in all matter; for example he believed that it was the glass in a Leyden jar that held the accumulated charge. He posited that rubbing insulating surfaces together caused this fluid to change location, and that a flow of this fluid constitutes an electric current. He also posited that when matter contained too little of the fluid it was "negatively" charged, and when it had an excess it was "positively" charged. Arbitrarily (or for a reason that was not recorded) he identified the term "positive" with vitreous electricity and "negative" with resinous electricity. William Watson arrived at the same explanation at about the same time. We now know that the Franklin/Watson model was close, but too simple. Matter is actually composed of several kinds of electrically charged particles, the most common being the positively charged proton and the negatively charged electron. Rather than one possible electric current there are many: a flow of electrons, a flow of electron "holes" which act like positive particles, or in electrolytic solutions, a flow of both negative and positive particles called ions moving in opposite directions. To reduce this complexity, electrical workers still use Franklin's convention and they imagine that electric current (known as conventional current) is a flow of exclusively positive particles. The conventional current simplifies electrical concepts and calculations, but it ignores the fact that within some conductors (electrolytes, semiconductors, and plasma), two or more species of electric charges flow in opposite directions. The flow direction for conventional current is also backwards compared to the actual electron drift taking place during electric currents in metals, the typical conductor of electricity, which is a source of confusion for beginners in electronics.

Properties

Aside from the properties described in articles about electromagnetism, charge is a relativistic invariant. This means that any particle that has charge q, no matter how fast it goes, always has charge q. This property has been experimentally verified by showing that the charge of one helium nucleus (two protons and two neutrons bound together in a nucleus and moving around at incredible speeds) is the same as two deuterium nuclei (one proton and one neutron bound together, but moving much more slowly than they would if they were in a helium nucleus).

Conservation of charge

The total electric charge of isolated systems remains constant regardless of changes within the system itself. This law is inherent to all processes known to physics and can be derived in a local form from Maxwell's equation as a continuity equation. More generally, the net change in charge density

\rho

within a volume of integration

V

is equal to the area integral over the current density

J

on the surface of the volume

S

, which is in turn equal to the net current

I

: :

- \frac \int_V \rho dV = \int_S \mathbf \cdot \mathbf = I

External links

- [http://www.unitconversion.org/unit_converter/charge.html Online Charge Converter] - convert between various units of charge, such as coulomb, EMU of charge, franklin, ampere-hour, faraday, and so on
- [http://www.unitconversion.org/unit_converter/charge-v.html Interactive Charge Conversion Table] - convert selected unit to all other units of charge
- [http://www.ce-mag.com/archive/2000/marapril/mrstatic.html How fast does a charge decay?]
- Category:Electricity Category:Physical quantity Category:Chemical properties Category:Introductory physics Category:Fundamental physics concepts ko:전하 ja:電荷

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Muda

Defects

Overproduction

Transportation

Waiting

Inventory

Motion

Overprocessing

Skill

External links

Toyota Production System

Commonly used terminology in TPS:

References

See also

External links

Electric polarity

Overview

History

Properties

Conservation of charge

See also

External links