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Mechanical Engineering

Effect of Electrode Extension (Stickout)

When an electric current flows through a conductor, a certain amount of heat is generated due to the current having to overcome the electrical resistance of the conductor. This is called resistance heating and it is proportional to I2 x R where I is the current and R is conductor …

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Effect of Polarity

The electric current used in a welding arc may be either direct current (DC) or alternating current (AC). Direct current flows constantly in one direction. Alternating current is continually changing direction. When direct current is used for welding, the welding electrode (consumable or nonconsumable) can be the positive pole or …

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Magnetic Field Associated with a Welding Arc

When an electric current passes through a conductor, a magnetic field is created that surrounds the conductor (Figure 1.6). Unless this magnetic field is balanced in all directions, the welding arc will tend to be deflected from its normal axial orientation in line with the electrode. This phenomenon is called …

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Arc Efficiency (welding)

The welding arc provides the intense heat needed to locally melt the workpiece and the filler metal. In fact, all the electrical energy supplied by the power source is converted into heat (current x voltage). Some energy is lost in the electrical leads, and therefore the energy available for welding …

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The Welding Arc

Most metals and alloys conduct electricity at room temperature due to the presence of free electrons. A considerable amount of heat can be produced from the flow of the current in a circuit. Typical examples of this heating effect, also called resistance heating, are tungsten filament bulbs and heating coils …

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Grouping of Welding Processes

There are many ways in which welding processes may be grouped and different countries have adopted various classification schemes based on the application of heat, whether external pressure is applied, the type of energy involved (mechanical, electrothermic, thermochemical), etc. The American Welding Society (AWS) groups welding processes based primarily on …

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What Is a Fluid?

What Is a Fluid? You will recall from physics that a substance exists in three primary phases: solid. liquid, and gas. (At very high temperatures. it also exists as plasma.) A substance in the liquid or gas phase is referred to as a fluid. Distinction between a solid and a …

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MANUFACTURING SYSTEM

Manufacturing basically implies making of goods or articles and providing services to meet the needs of mankind. It creates value by useful application of physical and mental-labor in the process. It is a chain of interrelated activities of production process and other support services activities of an manufacturing environment such …

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KINDS OF PRODUCTION SYSTEMS

The choice of production type dictates the machine requirements, organizational system to a large extent, layout planning and inventory subsystems. Three main types of production are job, batch and flow or process production. The simplest way is to classify based on production and processes by lot size, namely single unit …

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COMPUTER AIDED MANUFACTURING (CAM)

The computer aided manufacturing implies manufacturing itself, aided or controlled by computers. In a wider sense, it denotes all the activities in the manufacturing environment like use of computers in inventory control, project management, material requirement planning, data acquisition, testing and quality control. Improved reliability in view of the better …

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