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[Audio] Welcome everyone! Today our presentation will focus on the wide range of topics relating to heating and welding, as presented by Dr. S. Ramesh Kumar. We will cover the advantages of electric heating, heat transfer methods, various types of electric heating and welding, and power supply for arc welding. Let's get started!.

[Audio] Electric heating has many advantages compared to other forms, such as being more cost-efficient and offering more precise control. The different modes of heat transfer and methods of electric heating include resistance heating, arc furnaces, induction heating, and dielectric heating. The two major types of electric welding are resistance welding and arc welding. For arc welding, different power supplies are used and there are various types of radiation welding..

[Audio] Electric heating is an effective way to produce heat as it enables us to quickly and efficiently convert energy into heat through the use of electricity. This is possible due to the Joule's Law of Heating which states that the amount of heat generated is proportional to current, resistance, and time for which the current flows. From space heating to cooking to industrial processes, electric heating is applicable in a variety of applications, making it a highly useful technology..

[Audio] Slide presentation discussed Joule's law and its relevance to heating and welding. Joule's law captures the relationship between current, resistance, time and power which are all essential ingredients of heating and welding. Specifically, it states that when a current with an intensities of I amperes flows through a resistance of R ohms maintained for T seconds, the amount of work done is I squared times R times T in joules. This law is highly beneficial in determining the energy necessary for heating or welding any object. Moreover, Joule's constant J is defined as the number of work units that generates one unit of heat when totally transformed to heat. It is set at 4.2 joules per calorie and 1 calorie is equivalent to 4186 joules. Hopefully, this information has been useful..

[Audio] The specific heat capacity of a substance is the amount of heat energy required to increase the temperature of a given quantity of the substance. The equation for this is Q = WxCp x ∆T, with Q being the amount of heat energy, W the weight of the substance, Cp the specific heat of the material and ∆T the change in temperature. As an example, a mass of 200 grams, with a specific heat of 1 calorie per gram per degree Celsius, and requiring an increase in temperature from 20° Celsius to 100° Celsius, would require 16000 calories of heat energy..

[Audio] Electric heating is an efficient and clean method of heating and welding. It eradicates dust and ashes and keeps the environment clean, without interfering with the atmosphere. It offers high precision and control while delivering consistent heating despite the material in the process. Moreover, it requires fewer attention spans so you can quickly pinpoint certain areas and do heat treatments without having to stay vigilant throughout the entire process. Electric heating is a great answer for numerous heating and welding purposes..

[Audio] Electric heating has revolutionized how we employ heat in the workplace. It runs silently, making it ideal for busy industrial settings. It can reach high temperatures quickly and can be installed in a much more compact size, saving valuable floor space. Moreover, its placement near the point of use eliminates the need for additional transportation costs. Electric heating has enabled us to do more with less..

[Audio] Heat transfer is an important concept in engineering, referring to the movement of thermal energy from one object or area to another. There are three ways in which heat can be transferred: conduction, convection, and radiation. Conduction involves heat travelling by contact, while convection is the transfer of heat using fluid flow. Radiation does not require a medium and can travel through air, vacuum, and solid objects..

[Audio] Heat transfer is an important concept to understand when studying heating and welding. In this lesson, we'll explore the five different modes of heat transfer. We'll look at the diagram to gain a better understanding of how heat moves from one place to another. We'll also look at examples to help us comprehend the concept. Finally, we'll take a quiz to evaluate our understanding of the material..

[Audio] Heat transfer is a process which involves the exchange of thermal energy between two substances. It can be classified into three types - conduction, convection and radiation. Conduction is a process of the heat transfer between two objects which are in direct physical contact. Convection is when heat transfer is caused by the motion of a fluid. Radiation occurs when heat transfers between two bodies which are not in direct contact..

[Audio] Conduction is the direct transfer of heat between neighboring atoms or molecules, typically through a solid. Take the metal handle of a pan on a stove; when you touch it you feel the heat because it has conducted that heat to your hand. All of this is quantified through the Conduction Equation, which calculates the heat transfer per unit time based on the coefficient of thermal conductivity of the substance, the area of exposed heat transfer, the temperature of the hot region, the temperature of the cold region, and the thickness of the body..

[Audio] Convection is a process of energy transfer through the movement of a fluid, or a gas. Boiling water on the stove and air currents around a campfire are both examples of convection, as are ocean currents driven by warm air rising near the equator and cooler air sinking and replacing it near the poles. Convection ovens, which circulate heated air for more even cooking than a regular oven, also use convection. To better understand convection and its relation to heating and welding, let's take a closer look..

[Audio] Heat transfer is an essential physical process in many practical applications. The equation for calculating the heat transfer, denoted by Q, is shown in this slide. The equation for heat transfer is determined by multiplying the coefficient of convective heat transfer, hc, the area of heat transfer, A, and the difference between the surface temperature, Ts, and the fluid temperature, Tf. It is evident that an increase in any one of these factors will lead to an increase in the heat transfer..

[Audio] Radiation is an energy transfer method which is often misunderstood. It is a form of energy that does not need a medium to travel through and can be found in various forms throughout our lives. Burner elements of a stove, microwave ovens and even the sun emit radiation in the form of light, heat and other types of radiation. Uranium-238 is an example of radiation emission as it decays and is used in beneficial ways, such as heating food quicker and more evenly. Radiation has a part to play in making lives more convenient and productive..

[Audio] Today, we will discuss the mathematical formula that relates the net power of radiation to other factors. This formula states that the net power of radiation, P, is equal to emissivity, e, multiplied by Stefan's constant, σ, multiplied by the area of radiation, A, multiplied by the difference between the radiator temperature, Tr, and the surrounding temperature, Tc. We can use this formula to understand the relationship between the net power of radiation and the other variables in the equation, and ultimately how heat is transferred in a variety of scenarios..

[Audio] Electric heating is a popular method for generating heat and temperatures, which plays a major role in numerous industries and engineering processes. It works by driving electricity through a resistance, creating an arc between two electrodes, using induction, or applying dielectric heating. Another way to generate heat is through bombardment by high-energy particles such as alphas, betas, gammas, and x-rays, or by accelerating ions. Electric heating enables various industries and processes to be improved, and create new, innovative solutions..

[Audio] Electric heating is an often employed procedure to heat metallic parts and work pieces for welding. This slide displays the various electrical heating techniques, such as power frequency, arc bombardment, high frequency, resistance, direct resistance, induction, dielectric, direct induction, indirect arc, indirect induction, indirect resistance and infrared or radiant heating. Every one of these methods has its own benefits and drawbacks, and selecting the most suitable one for the planned purposes is essential..

[Audio] Resistance heating has numerous uses in our lives, ranging from drying to cooking for both domestic and commercial purposes. It is also used to temper and strengthen metals. Resistance heating operates on the principle that an electric current, when passed through a conductor, dissipates some of its power as heat. The power loss can be computed using either the I²R watt, VI watt, or V²/R watt equations. Resistance heating provides a range of advantages from faster cooking to more durable products..

[Audio] Resistance heating is an efficient process of converting electrical energy to heat energy with minimal loss. It can be classified into three types: direct, indirect, and infrared or radiant heating. Direct resistance heating warms up the load or charge without any contact, while indirect resistance heating heats the air through convection currents. Infrared or radiant heating produces a similar effect to direct resistance heating, but without direct contact..

[Audio] Direct resistance heating is an efficient and convenient way to heat materials. Instead of using an external heat source, materials such as powder, liquid, or pieces serve as the path of current flow. As current passes through the material, resistance causes the material to heat up. This form of heating is widely used in equipment like resistance welding and electrode boilers, allowing for a controlled and efficient process to heat materials..

[Audio] Resistance heating is a process of transforming electrical energy into heat energy. It is brought about when an electric current encounters resistance in a conductor, like a metal wire. This resistance produces heat, which can then be utilized for a range of purposes, including melting metal, soldering, welding, and heat treating. Compared to other methods of producing heat, resistance heating is particularly energy-efficient, and is more and more being utilized in industrial and manufacturing settings..

[Audio] Indirect resistance heating is a technique that uses a high resistance element to generate heat which is then transferred to the desired area without direct contact. Heat is instead transferred through conduction, convection, or radiation. This method can be employed in multiple tasks safely due to its precision in applying heat to the specific area while also minimizing risk of damage to the surroundings..

[Audio] Radiant heating is an effective means of distributing heat. It employs tungsten filament lamps along with reflectors to reflect the heat onto the source. These lamps range from 250 to 1000 Watts and operate at an approximate temperature of 2300° Celsius, producing high concentrations of infrared radiation. This is ideal for drying painted surfaces. One of the most popular choices is the Heatstrip Infrared Radiant Heater. It is an efficient way to transfer warmth without consuming excess energy..

[Audio] Electric arc furnaces are employed in a range of industrial uses due to their ability to melt and weld metals. The arc is produced when an electric current passes across the space between two electrodes, reaching temperatures as high as 10000°C. This intense heat is enough to melt and even vaporize metals. Once the arc has been started, a standard voltage is sufficient to maintain the arc and supply a continuous source of heat. These furnaces can be used in the manufacture of specialty steels, joining of metals and metallurgical research..

[Audio] Electric Arc Furnace is a type of furnace that uses electrical current to melt and fuse materials such as metals and alloys. Reaching temperatures of up to 11000°C, it is an incredibly efficient and cost-effective way of melting metal, leading to its frequent use in industrial applications. Among other metals, it is commonly used to produce steel, copper, aluminum, and magnesium..

[Audio] Arc furnaces are a type of heated and welding tool that come in two shapes - cylindrical and conical. The conical design provides more surface area per unit volume, leading to lower power requirements, lower radiation loss, and lower melting points. The arc chamber of the furnace is lined with an acid or basic refractory and held in place by a metal frame. Electodes are held in place by a clamping mechanism on the top or sides of the chamber for easy adjustment or replacement. Additionally, a charge door is provided on the side for the placement of the charge and removal of molten metal..

[Audio] Electric arc furnaces are an important tool in metalworking, using electricity to heat metal elements to temperatures suitable for welding and other forms of thermal joining. Consisting of three parts - electrodes, power sources, and refractory lining - there are three main types of electric arc furnaces. The direct electric arc furnace has one electrode in the center of the vessel and electricity passes directly through the material being heated, allowing for intense heat, but limited space. The indirect electric arc furnace uses two electrodes along the side of the vessel and generates heat by heating the refractory lining on the inside of the vessel. Finally, the submerged electric arc furnace is the most advanced type and has multiple electrodes in the bottom of the vessel, generating heat and metal vapor by immersing the material in the molten slag..

[Audio] Two carbon or graphite electrodes are used in a direct arc furnace to form an arc between them and the charge, leading to a more efficient furnace. This furnace is known for its reliable and energy-efficient performance..

[Audio] Arc furnaces are a type of heating process that can generate high temperatures by directly connecting a charge to an electric arc. Single-phase arc furnaces have two vertical electrodes placed within the furnace, while three-phase arc furnaces have three electrodes placed in the corners in the form of an triangle. Furthermore, this type of furnace can produce additional heat through current flow, with its stirring action being produced by the electromagnetic force of the current. These factors make direct arc furnaces a popular choice for producing steel, being a more advantageous choice when compared to cupola methods..

[Audio] An arc furnace is a commonly used welding method in industrial manufacturing, particularly in the production of metals. In direct arc furnaces, the arc is in direct contact with the charge, making efficient heating of the material possible. However, an indirect arc furnace offers several advantages. The arc is generated between two electrodes that are kept separated from the material being welded, and heat is applied through radiation instead. This helps prevent contamination, as well as uneven heating and potential contamination of substances that are sensitive to heat. As a result, the indirect arc furnace is a significant component in industry, and its uses and capabilities are continually being improved..

[Audio] Indirect arc furnaces are an efficient way to heat and weld metals by creating an arc between two electrodes that don't come into direct contact with the charge. This method leads to lower temperatures than from a direct arc furnace, and further control is achieved by adjusting the arc length. Generally, this type of furnace is single-phase and limited in size, and is used to melt non-ferrous metals or in iron foundries when molten metal is required..

[Audio] Submerged arc furnaces are advantageous in many industrial settings for the production of ferroalloys. They feature a high melting rate, low fuel consumption, and minimal manual labor. A resistance of the charge to the current flow causes heat which can be regulated by adjusting the voltage or the length of the arc. Examples of molten ferroalloys created with this type of furnace include Fe-Mn, Si-Mn, Fe-Si, Mg-Si, and more..

[Audio] Induction heating is a method of electrical heating which enables metals to be heated without physical contact. It works by using an electrical current to create an electromagnetic field, resulting in heat generation within the conducting material. This is especially beneficial when heating up metals in a specific area, as it is more precise than using flames which may heat up a larger area. Induction heating is advantageous as it allows for precise temperature control and quicker production times..

[Audio] Electric heating is one of the most efficient and reliable methods of heating available. The transfer of heat takes place in three ways – conduction, convection, and radiation. The main advantage of electric heating is that it does not require moving parts, making maintenance much simpler. Compared to traditional heating methods, electric heating is faster and can be adjusted to provide various levels of heat. Additionally, electric heating is more compact meaning it can be used in tighter spaces. High-frequency heating is particularly efficient, as the electric energy is changed into heat within the material itself..

[Audio] Induction heating and dielectric heating are two distinct techniques used for heating materials. Induction heating is used when you want to heat conducting materials such as metals. The process of induction heating involves running an electric current through a material, which produces heat on the material's surface. Dielectric heating, on the other hand, is used when insulating materials such as wood need to be heated. This technique uses an electric field to induce heat in the material. Regardless of the material being heated, these two heating methods can be used to heat various materials quickly and efficiently..

[Audio] Induction heating uses both Faraday’s law of electromagnetic induction and the concept of Joule heating to generate heat. This process works similarly to a transformer, where an alternating magnetic field is generated when the primary winding is energized. This magnetic field then links with a secondary winding, producing an electromotive force and resulting in an electric current. This current produces heat as it passes through the material due to its internal resistance, according to the Joule effect. Induction heating is a direct and efficient way to generate localized heat through the use of electric current..

[Audio] Induction heating involves passing high-frequency alternating current through a coil which generates an alternating magnetic field. The magnetic field induces an electric current in the workpiece when placed within the coil, which creates resistive heat. This is somewhat similar to a transformer, but the workpiece is not short circuited as it would be in a transformer. This heat generated can be utilised in a variety of applications, for example welding and hardening of metal surfaces..

[Audio] Induction heating is a contactless way to heat using an electromagnetic field. This method of heating is used for various tasks, including welding, bending, and hardening of engineering components. To use induction heating, a workpiece, power supply, control circuit, work coil, and a high frequency alternating current signal are required. When the AC current passes through the work coil, it creates an electromagnetic flux which then interacts with the workpiece and causes it to heat. This induction heating process is swift and effective. It is a great choice for tasks such as welding, bending, and hardening as it is fast and efficient..

[Audio] Joule Effect states that when current flows through the material, it encounters a finite resistance, resulting in the dissipation of power in the form of heat through the material. At high-frequency operations, Skin effect can occur, where the current becomes concentrated at the surface of the material and going deeper within, the eddy currents reduce..

[Audio] Induction heating is an effective and sought after way of heating and welding parts. It is advantageous for its high degree of penetration, its capacity to concentrate heat onto the surface, and its swift and efficient heating that saves energy. Furthermore, its automated control system offers automatic temperature control with no environmental harm. The only drawback is the costly high-frequency power source necessary for its functioning, and the requirement for electricity during the process..

[Audio] Induction heating is a process that utilizes electrical current to heat materials, such as metals, to extremely high temperatures. It is employed in induction furnaces for heating different kinds of materials. Induction furnaces can be divided into two categories: core type or low-frequency furnaces, and coreless type or high-frequency furnaces. This procedure has multiple benefits, including efficient and controlled heating, enabling more consistent and precise temperatures when heating materials..

[Audio] A core type or low frequency induction furnace has a circular hearth in the form of a trough with a large iron core inside linked to an electrical winding energized by an AC source. The hearth holds the charge to be melted in the form of an annular ring, heating it up quickly and efficiently, making it an ideal choice for melting and heating materials quickly and easily..

[Audio] Core type induction furnaces are invaluable for heating and melting metal and other substances. A direct core type induction furnace involves short-circuiting the charge, forming a single turn secondary circuit, and magnetically coupling the primary current with an iron core. This generates a powerful current that causes the charge to melt. Without a molten metal, no current will be induced. Therefore, prior to using the furnace, molten metal must be transferred into the hearth. An indirect core type induction furnace uses a heating element that forms the secondary, and the heat it produces is then radiated to the charge. These types of induction furnaces provide an effective and dependable approach to heat and weld metal..

[Audio] Coreless induction furnaces are a practical way to heat materials. This is because they do not have a core, rather the heating is generated from the eddy currents created by the alternating magnetic field. This method of heating is versatile and easy to use, making it suitable for a variety of materials. All in all, it is an efficient and dependable way to heat materials..

[Audio] Induction furnaces are a useful device for heating materials, consisting of a ceramic or refractory crucible surrounded by a coil connected to alternating current power. This alternating current produces eddy current in the charge being heated, generating heat as well as a stirring action due to electromagnetic forces. Since there is no core in the furnace, the flux density is low, so the primary must be supplied by high-frequency current, making this furnace suitable for certain applications..

[Audio] Dielectric heating is an efficient and effective way of heating non-conductive materials using a high frequency alternating electric field, radio frequency or microwave electromagnetic radiation. Often referred to as capacitive heating, this process ensures the material heats up in a uniform manner. It works by passing a high frequency voltage between two electrodes connected to a high voltage RF source, with the dielectric material, or workpiece, placed between them. This method of heating is increasingly used in industrial operations..

[Audio] Dielectric heating is a highly efficient and cost-effective method for heating non-conducting materials such as plastics, fabrics, and papers. By applying alternating voltage of high frequency across two metal electrodes with a dielectric material between them, the material is quickly and evenly heated without the need of direct heat. This is attributed to the dynamic electrostatic field between the electrodes, which generates electrical energy that is then converted into heat energy. Therefore, this way of heating is both energy efficient and does not generate hazardous by-products, making it a suitable option for a multitude of applications..

[Audio] Essential to understand that at lower frequencies, like 50 Hz, power losses in capacitance plate dielectric will be negligible. This means we can use this set up to heat dielectric for various purposes, including welding, brazing and soldering. At higher frequencies, like in megahertz range, power loss is significantly higher, enabling us to effectively use this set up for heating dielectrics..

[Audio] We need to take into account the variables of supply voltage, frequency, electrode area, thickness of the dielectric, loss angle and capacitance to calculate the heating in welding. The equation we obtain helps us calculate the heating in welding, enabling us to adjust the welding parameters accordingly. This is done by calculating the power supplied to the load and the power losses in the system due to losses in the dielectrics..

[Audio] Dielectric heating is a process that utilizes electric fields to heat materials. It involves the molecular response of the material to an alternating electric field, resulting in internal heating and a uniform and efficient rate of heating. This method has been employed in the manufacturing industry as it can speed up and maximize production processes..