MORNING STAR POLYTECHNIC COLLEGECHUNKANKADAI
ELECTRIC INDUCTION FURNACEA Project ReportIn partial fulfillment of the requirement for the award of diplomaInMECHANICAL ENGINEERINGProject guided byMr.T.KAMILLAS FRANKLIN,M.ESubmitted ByNAMESL.NO
J.AJEESH12208566
P.AJIN RAJ12208568
P.ALAN BINO SUGIHAR12208570
R.ALEX12208571
A.ALEX MON12208572
A.M.ANAND12208573
DIRECTORATE OF TECHNICAL EDUCATION, TAMILNADU2013-2014MORNING STAR POLYTECHNIC COLLEGECHUNKANKADAI
Department Of Mechanical EngineeringCERTIFICATEThis is to certificate that the project entitled ELECTRIC INDUCTION FURNACE is a bonafide work done by.. reg.no........ of final year diploma in mechanical engineering, during the year 2013-2014.
Guide Head Of The Department Mr.T.KAMILLAS FRANKLIN,M.E Mr.T.KAMILLAS FRANKLIN,M.E
Submitted For The Board Examination Held At Morning Star Polytechnic College On ..
Internal Examiner External ExaminerPlace : ChunkankadaiDate :
ELECTRIC INDUCTION FURNACE
INTRODUCTION
INTRODUCTIONAninduction furnaceis an electricalfurnacein which the heat is applied byinduction heatingofmetal. The advantage of the induction furnace is a clean, energy-efficient and well-controllable melting process compared to most other means of metal melting. Most modernfoundriesuse thistypeof furnace and now also more iron foundries are replacingcupolas with induction furnaces to meltcast iron, as the former emit lots ofdustand otherpollutants.Induction furnace capacities range from less than one kilogram to one hundred tonnes capacity and are used to meltironandsteel,copper,aluminiumandprecious metals. Since no arc or combustion is used, the temperature of the material is no higher than required to melt it; this can prevent loss of valuable alloying elements.The one major drawback to induction furnace usage in a foundry is the lack of refining capacity; charge materials must be clean of oxidation products and of a known composition and some alloying elements may be lost due to oxidation (and must be re-added to the melt).Operating frequencies range fromutility frequency(50 or 60Hz) to 400kHz or higher, usually depending on the material being melted, the capacity (volume) of the furnace and the melting speed required. Generally, the smaller the volume of the melts, the higher the frequency of the furnace used; this is due to theskin depthwhich is a measure of the distance an alternatingcurrentcan penetrate beneath the surface of aconductor. For the same conductivity, the higher frequencies have a shallow skin depththat is less penetration into the melt. Lower frequencies can generate stirring or turbulence in the metal.
1-Melt2-water cooledcoil3-yokes4 - crucibleA preheated, one-tonne furnace melting iron can melt cold charge to tapping readiness within an hour. Power supplies range from 10kW to 42MW, with melt sizes of 20kg to 65tonnes of metal respectively. An operating induction furnace usually emits a hum or whine (due to fluctuating magnetic forces andmagnetostriction), the pitch of which can be used by operators to identify whether the furnace is operating correctly or at what power level.
DIAGRAM
DIAGRAM
COMPONENTS
COMPONENTS
Crucible Inductor coil and shell Cooling system Tilting mechanism. CRUCIBLEAcrucibleis a container that can withstand very high temperatures and is used for metal,glass, andpigmentproduction as well as anumberof modern laboratory processes. While crucibles historically were usually made from clay,[1]they can be made from any material that withstands temperatures high enough to melt or otherwise alter its contents.Crucibles and their covers are made of high temperature-resistant materials, usuallyporcelain,aluminaor aninertmetal. One of the earliest uses ofplatinumwas to make crucibles. Ceramics such asalumina,zirconia, and especiallymagnesiawill tolerate the highest temperatures. More recently, metals such asnickelandzirconiumhave been used. The lids are typically loose-fitting to allow gases to escape during heating of a sample inside. Crucibles and their lids can come inhigh formandlow formshapes and in various sizes, but rather small 1015mlsize porcelain crucibles are commonly used forgravimetric chemical analysis. These small size crucibles and their covers made of porcelain are quite cheap when sold in quantity to laboratories, and the crucibles are sometimes disposed of after use in precise quantitative chemical analysis. There is usually a large mark-up when they are sold individually inhobby shops.
INDUCTOR COIL AND SHELLAninductor, also called acoilorreactor, is apassivetwo-terminalelectrical componentwhich resists changes inelectric currentpassing through it. It consists of a conductor such as a wire, usually wound into a coil. When acurrentflows through it,energyis stored temporarily in amagnetic fieldin the coil. When the current flowing through an inductor changes, the time-varying magnetic field induces avoltagein the conductor, according toFaradays law of electromagnetic induction, which opposes the change in current that created it.An inductor is characterized by itsinductance, the ratio of the voltage to the rate of change of current, which has units ofhenries(H). Inductors have values that typically range from 1 H (106H) to 1 H. Many inductors have amagnetic coremade of iron orferriteinside the coil, which serves to increase the magnetic field and thus the inductance. Along withcapacitorsandresistors, inductors are one of the three passivelinearcircuit elementsthat make up electric circuits. Inductors are widely used inalternating current(AC) electronic equipment, particularly inradioequipment. They are used to block AC while allowing DC to pass; inductors designed for this purpose are calledchokes. They are also used inelectronic filtersto separate signals of differentfrequencies, and in combination with capacitors to maketuned circuits.
COOLING SYSTEMMetalcasting cooling systems normally operate quietly in the background and receive regular attention only from the maintenance personnel tasked with keeping them running. The goal for this article is to provide useful insights into the design and operation of effective and efficient induction melt shop cooling systems, with real-world illustrations drawn from a new system installed at Chassix Columbus Casting Operation, Columbus, Ga. Chassix is a $1.2 billion global company headquartered in Southfield, Mich., serving automotive customers from 25 locations in eight countries. Its Columbus facility melts 240,000 tons of ductile iron per year.
COOLING SYSTEM BASICS
Induction furnaces of all types and sizes normally are cooled by water flowing through the furnaces coils, which are made of heavy copper tubing. These coils generate high levels of heat, principally from the enormous electrical currents flowing through them and only to a much lesser extent from heat produced by the molten metal held in the furnace. Induction power supplies also require water cooling of their electrical components. Without an effective cooling system, induction furnaces will not operate.At its most basiclevel, an induction furnace cooling system includes pumps circulating water through the furnace to absorb heat and on to a cooling tower where that heat is released. But to be safe and effective, a cooling system must incorporate a variety of vital subsystems. These include: Filters and other devices to keep the water clean and flowing. Heat exchangers, inline heaters and cold water diversion valves to maintain the optimal water temperature. Automatic city water makeup to keep the cooling system full. Flow sensors, pressure gauges, thermometers, water meters, and other monitoring and control devicesneededto be sure its all working properly. An emergency backup system to maintain furnace cooling in the event of pump failure or power outage.Because cooling systems are so essential, when the system at Chassix was no longer able to meet its needs, the management team moved quickly to repair or replace it.According to Darold Jack Roop, senior project engineer, Chassix, the problems with the old cooling system had increased considerably when new furnaces were installed to support growth in the companys casting business.We added three 12.5 metric tons per hour,mediumfrequency induction furnaces for batch melting, along with their power supplies, compressors and hydraulics, Roop explained. But our cooling system lacked the capacity to handle this new load. Due to inadequate cooling, the furnaces frequently overheated and tripped out. Several coils were burned up. We did not have sufficient cooling to allow us to run all of our furnaces at the same time. This reduced our metal production and limited our ability to fully benefit from the new melting capacity we had just added.Chassix determined repairs to the existing cooling system would not provide the cooling capacity needed, so it set up and funded a project to replace much of the system. Chassix project manager Frank Burton oversaw the creation of the new cooling system.Our cooling tower was old, the wood was rotting and falling apart and its three pumps had to run all the time to provide needed cooling, he said. There was no redundancy. If one pump failed, production had to be shut down until the pump could be replaced. Shutting down was a slow process. The only emergency backup was city water, and that outflow presented environmental concerns.
DESIGNING AN INDUCTION MELT COOLING SYSTEM
Very small induction furnaces used in labs or for melting small quantities of precious metals may be cooled by direct connection to an incoming city water recirculated back through the furnace. This is the basis of most cooling systems.To design a cooling system for an induction melt shop, first you must determine the heat load on the system, taking into account the size of each furnace, the power applied, the metal melted, type of melting (batch or heel), holding and pouring times and the heat loads added by non-furnace ancillary equipment.These calculations can be complex. The new cooling system for Chassix was based on heat load calculations for the facilitys wide variety of furnace sizes, melting processes and ancillary equipment used to support them. These included: Three 12.5-metric-ton, medium frequency induction batch melting furnaces. Five 10-ton line frequency induction heel melting furnaces. Two 17-ton line frequency induction heel melting furnaces. Ancillary systems including air compressors, hydraulic pumps and air conditioners.The calculations also had to take into account the need for backup capacity to maintain cooling during equipment maintenance or repair and to support future growth.I was looking for a new cooling system that would be reliable and offer the redundancy to enable it to continue running even with a pump failure, Burton said. I also wanted a system that would provide not just the capacity to cool all of our furnaces and equipment running at the same time, but that would have the additional capacity to support anticipated future growth.The next step in the overall cooling system design is to make adjustments for the desired incoming water temperature from the tower to the process, the outgoing water temperature from the process to the tower and the climatic data for the foundry location.line and use a city drain for the outflow. Most other size furnaces require a pump or pumps to push cooling water through the furnace and a cooling tower of some kind to remove the heat from the water, which is then
WORKING
WORKINGThe heart of thecoreless induction furnaceis the coil, which consists of a hollow section of heavy duty, high conductivity copper tubing which is wound into a helical coil. Coil shape is contained within a steel shell and magnetic shielding is used to prevent heating of the supporting shell. To protect it from overheating, the coil is water-cooled, the water bing recirculated and cooled in a cooling tower. The shell is supported on trunnions on which the furnace tils to facilitate pouring.The crucible is formed by ramming a granular refractory between the coil and a hollow internal former which is melted away with the first heat leaving a sintered lining.The power cubmicle converts the voltage and frequency of main supply, ot that required for electrical melting. Frequencies used in induction melting vary from 50 cycles per second (mains frequency) to 10,000 cycles per second (high frequency). The higher the operating frequency, the greater the maximum amount of power that can be applied to a furnace of given capacity and the lower the amount of turbulence induced.When the charge material is molten, the interaction of the magnetic field and the electrical currents flowing in the induction coil produce a stirring action within the molten metal. This stirring action forces the molten metal to rise upwards in the centre causing the characteristic meniscus on the surface of the metal. The degree of stirring action is influenced by the power and frequency applied as well as thesizeand shape of the coil and the density and viscosity of the molten metal. The stirring action within the bath is important as it helps with mixing of alloys and melting of turnings as well as homogenising of temerature throughout the furnace. Excessive stirring can increase gas pick up, lining wear and oxidation of alloys.The coreless induction furnace has largely replaced thecrucible furnace, especially for melting of high melting point alloys. The coreless induction furnace is commonly used to melt all grades of steels and irons as well as many non-ferrous alloys. The furnace is ideal for remelting and alloying because of the high degree of control over temperature and chemistry while the induction current provides good circulation of the melt.
ADVANTAGES
ADVANTAGES Safe operation Pollution can be reduced Electric induction is used to melt the material Less power consumption
APPLICATIONS
APPLICATIONS
Automobile industry Aluminum melting furnace Industrial application
CONCLUSION
CONCLUSION
The development of this project from the theoretical aspects to its practical application is of immense contribution. The Induction furnace design and subsequently its fabrication should be promoted considering the abundant power sources, less maintenance cost and labor requirements.
REFERENCES
REFERENCES1. Percy, John.Natural Refractory Materials Employed in the Construction of Crucibles, Retorts, Forunaces &c.Metallurgy. London: W. Clowes and Sons, 1861. 20809. Print.2. Jump up^Pigott, Vincent C. "The Neolithic (C.A 75005500 B.C) and Caltholithic (C.A 55003200 B.C) Periods." The Archaeometallurgy of the Asian Old World. Philadelphia: UPenn Museum of Archaeology, 1999. 7374. Google Scholar. Web.3. Jump up^Rehren T. & Thornton C. P, 2009,A truly refractory crucible from fourth millennium Tepe Hissar, Northeast Iran, Journal of Archaeological Science, Vol. 36, pp270027124. ^Jump up to:abHauptmann A., 2003,Developments in copper Metallurgy During the Fourth and Third Millennia B.C. at Feinan, Jordan, P. Craddock & J. Lang, Eds, Mining and Metal Production Through the Ages, British Museum Press, London, pp931005. ^Jump up to:abRehren Th., 2003,Crucibles as Reaction Vessels in Ancient Metallurgy, Ed in P. Craddock & J. Lang, Mining and Metal Production Through the Ages, British Museum Press, London pp2072156. Jump up^Rehren Th., 1999,Small Size, Large Scale Roman brass Production in Germania Inferior, Journal of Archaeological Science, Vol. 26, pp 108310877. Jump up^Craddock P., 1995,Early Metal Mining and Production, Edinburgh University Press Ltd, Edinburgh8. ^Jump up to:abRehren, Th. and Papakhristu, O., 2000,Cutting Edge Technology The Ferghana Process of Medieval crucible steel Smelting, Metalla, Bochum, 7(2) pp55699. Jump up^Martinon-Torres M. & Rehren Th., 2009,Post Medieval crucible Production and Distribution: A Study of Materials and Materialities, Archaeometry Vol.51 No.1 pp4974
