- A CASE STUDY

AT KAKKU ELECTRONIC & POWER CONTROL COMPANY, LIGHT INDUSTRIAL AREA, BHILAI, CHHATTISGARH, INDIA

This project report and case study aims to celebrate the special qualities of Electromagnets and tries to describe the complete process of how industry grade electromagnets are ordered, designed, manufactured, and tested. I have explained the procedure thoroughly by utilizing the knowledge gained while interning at Kakku Electronic & Power Ltd.

NEELANSH KAABRA DPS, BHILAI, CHHATTISGARH INDIA NOVEMBER-DECEMBER 2019

INTRODUCTION

Magnets play an integral role in our lives. This case study aims to highlight the importance of magnets in the human world, the special qualities of electromagnets and about the actual process of making industry grade electromagnets.

Magnets are objects that generate a , a force-field that either pulls or repels certain materials, such as steel and iron. The focus of this case study will be on a special type of magnet known as Electromagnets. Electromagnets work on a fundamental force called electromagnetism. In the 19th Century, Hans Christian Ørsted noticed that a wire with a current running through it affected a nearby compass. The current was creating a magnetic field. Later research showed that electric current and are actually two aspects of the same force. This force works both ways – a moving magnetic field creates electric current. An can be defined as a magnet which functions on electricity. Unlike a permanent magnet, the strength of an electromagnet can be altered. By controlling the electric current we can control the magnetic field, i.e., the strength of electric field controls the strength of magnetic field also. In fact, the poles of an electromagnet can even be reversed by reversing the flow of electricity. If the current flow is cut, the property of magnetism ceases to exist and that’s why an electromagnet is classified as a temporary magnet.

A simplified view of an atom, with a nucleus and orbiting electrons We know that an electrical current moving through a wire creates a magnetic field. But a magnet's field doesn't come from a large current traveling through a wire; it comes from the movement of electrons. Even though an atom's electrons don't move very far, their movement is enough to create a tiny magnetic field. Since paired electrons spin in opposite directions, their magnetic fields cancel one another out. Atoms of ferromagnetic elements, on the other hand, have several unpaired electrons that have the same spin. Iron, for example, has four unpaired electrons with the same spin. Because they have no opposing fields to cancel their effects, these electrons have an orbital magnetic moment. The magnetic moment is a vector; it has a magnitude and a direction. It's related to both the magnetic field strength and the torque that the field exerts. A whole magnet's magnetic moments come from the moments of all of its atoms.

An iron atom and its four unpaired electrons

In metals like iron, the orbital magnetic moment encourages nearby atoms to align along the same north-south field lines. Iron and other ferromagnetic materials are crystalline. As they cool from a molten state, groups of atoms with parallel orbital spin line up within the crystal structure. This forms the magnetic domains. You may have noticed that the materials that make good magnets are the same as the materials magnets attract. This is because magnets attract materials that have unpaired electrons that spin in the same direction. In other words, the quality that turns a metal into a magnet also attracts the metal to magnets. Many other elements are diamagnetic -- their unpaired atoms create a field that weakly repels a magnet. A few materials don't react with magnets at all.

DIFFERENCE BETWEEN ELECTROMAGNET AND PERMANENT MAGNET

Electromagnet Permanent Magnet

The magnetic properties are displayed when Magnetic properties exist when the material is current is passed through it magnetized

The strength is adjusted depending upon the The strength depends upon the nature of the amount of flow of current material used in its creation

Removal of magnetic properties is temporary Once magnetic properties is lost, it becomes useless

It requires a continuous supply of electricity to It doesn’t require a continuous supply of electricity maintain its magnetic field. to maintain its magnetic field

It is usually made of soft materials It is usually made of hard materials

The poles of this kind of magnet can be altered The poles of this kind of magnet cannot be changed. with the flow of current

TYPES OF ELECTRO MAGNETS

HIGH FIELD ELECTROMAGNETS

Most powerful electro magnet in the world at US National High Magnetic field Laboratory, Florida Superconducting electromagnets When a magnetic field higher than the ferromagnetic limit of 1.6 T is needed, superconducting electromagnets can be used. Instead of using ferromagnetic materials, these use superconducting windings cooled with liquid helium, which conduct current without electrical resistance. These allow enormous currents to flow, which generate intense magnetic fields. Superconducting magnets are limited by the field strength at which the winding material ceases to be superconducting. Current designs are limited to 10–20 T, with the current (2017) record of 32 T. The necessary refrigeration equipment and cryostat make them much more expensive than ordinary electromagnets. However, in high power applications this can be offset by lower operating costs, since after startup no power is required for the windings, since no energy is lost to ohmic heating. They are used in particle accelerators and MRI machines. Bitter electromagnets Both iron-core and superconducting electromagnets have limits to the field they can produce. Therefore, the most powerful man-made magnetic fields have been generated by air-core non superconducting electromagnets of a design invented by Francis Bitter in 1933, called Bitter electromagnets. Instead of wire windings, a Bitter magnet consists of a solenoid made of a stack of conducting disks, arranged so that the current moves in a helical path through them, with a hole through the center where the maximum field is created. This design has the mechanical strength to withstand the extreme Lorentz forces of the field, which increase with B2. The disks are pierced with holes through which cooling water passes to carry away the heat caused by the high current. The strongest continuous field achieved solely with a resistive magnet is 37.5 T as of 31 March 2014, produced by a Bitter electromagnet at the Radboud University High Field Magnet Laboratory, Netherlands. The strongest continuous magnetic field overall, 45 T, was achieved in June 2000 with a hybrid device consisting of a Bitter magnet inside a . The factor limiting the strength of electromagnets is the inability to dissipate the enormous waste heat, so more powerful fields, up to 100 T, have been obtained from resistive magnets by sending brief pulses of high current through them; the inactive period after each pulse allows the heat produced during the pulse to be removed, before the next pulse. Explosively pumped flux compression

A hollow tube type explosively pumped flux compression generator

The most powerful manmade magnetic fields have been created by using explosives to compress the magnetic field inside an electromagnet as it is pulsed; these are called explosive pumped flux compression generators. The implosion compresses the magnetic field to values of around 1000 T for a few microseconds. While this method may seem very destructive, it is possible to redirect the brunt of the blast radially outwards so that neither the experiment nor the magnetic structures are harmed. These devices are known as destructive pulsed electromagnets.

Uses of Electromagnets Clearly, there's a wide range of electromagnet applications between small, homemade science experiments and the Earth itself. Some electromagnet uses are given in the points mentioned below:  Motors and Generators  Transformers  Pickups, Relays (control switches)  Electric bells and buzzers  Loudspeakers and headphones , Amplifiers  Actuators such as valves  Magnetic recording and data storage equipment: tape recorders, VCR’s, Hard disks  MRI machines  Scientific equipment such as mass spectometers, Particle accelerators  Magnetic Locks, Magnetic separation equipment, used for separating magnetic from nonmagnetic material, for example separating ferrous metal from other material in scrap.  Industrial lifting magnets  Induction heating for cooking, manufacturing, and hyperthermia therapy  Spacecraft Propulsion Systems Induction Heating

MAGNETS MANUFACTURING AT KAKKU INDUSTRIES, BHILAI, INDIA

Kakku Electronic & Power Control Company (An Enterprise of Kakku E & P Control Pvt Ltd.), Bhilai, was founded in the year 1968 with a clear vision of "Make in India" through Import Substitution of EOT Crane electrics required by Core sector Industries both in India and abroad. Steadily but surely, the “KAKKU” tag made its presence felt in major Industries and its Product range which began with Electrical Relays, forayed into Control & Selector Switches, Conveyor Safety Switches , Master Controllers, Limit Switches, AC & DC Electro Magnetic Brakes, Lifting Electromagnets and many more.

KAKKU has 49+ years of experience with providing wide area of specialty services works listed above. A Company involved in servicing, maintenance and repairs of widest-range of Control Gears and Electro-mechanical Control Equipment, used in diverse application in a wide array of industries. Kakku Industries is known for its client-centered ideology. Every product is created according to the needs and desires of the customer and every step is taken to ensure complete satisfaction.

The core of the magnet is being prepared at Kakku Industries

Insulation of the core being done by applying a coat of ‘Sylartivi” (Silicon Rubber Compound)

Type of Lifting Electromagnets manufactured at Kakku Industries 1. Circular Magnet 2. Rectangular Magnet 3. Suspended Magnetic Separator 4. Lid Lifting Magnets

Sizes of Magnets Circular Magnet Diameter – 350 mm to Diameter – 2200 mm Rectangular Magnet Size: Length 600 to 2100 mm Width 300 to 700 mm Material / Composition Used in preparing of Magnets 1. Steel casting shell, Grade –II of IS-4491. Composition: Carbon – 0.25% Max Silicon – 0.6% Max Manganese – 0.50% Max S & P – 0.05 & Max Residual Elements – 0.8% Max 2. Rough forged blank, Grade –C-14. Composition: Carbon – 0.18% Max Silicon – 0.60% Max Manganese – 0.70% Max S & P – 0.055 & Max 3. Nonmagnetic Bumping Plate  Material – Stainless steel Grade J-4  High Manganese Steel Casting Grade IS-276 Composition Carbon – 1.05 to 1.35 % Max Silicon –1.0% Max Manganese – 11-14% Max S – 0.06% Max P- 0.09 % Max 4. Conductor- High conductivity electrolytic grade fully annealed Bare Aluminum Strip or Copper Strip or Double Glass fiber covered Aluminum or Copper strip, Grade IS-1987, Grade ETP of IS, hardness – 40 to 60 HV 5. Insulation Asbestos free mill board Flexible Mica Sheet Heater Mica Sheet Varnish Samsonite Sheet Glass tape Insulation paper, Class –H & Class- C Silicon Rubber Compound / Glass Epoxy Compound with Hardener Silicon Cable 6. Testing Megger Value by Insulation tester Resistance Value by Resistance Bridge High Voltage test (2 KV for 1 Min) by Abraham Voltmeter. 7. Uses Round Magnets -Designed For handling steel and cast iron objects like plates, pig iron scraps, sponge iron, solid steel ingots etc.

Rectangular Electro-magnets- Designed to handle long loads such as rails, Beams, billets, blooms & Pipes etc. Usually two or three electro-magnets suspended from one traverse beam are employed to lift such long loads. Suspended Magnetic Separator design is used to remove the ferrous materials over the side of a conveyor belt.

LIFTING ELECTROMAGNETS

Brief specification:

• Magnets with copper or aluminum coils. • Round magnets (diameter 800 mm to 2220 mm) - for lifting Sponge iron, Pig iron, M.S scrap. • Rectangular magnets – sizes as required by the customers – for lifting Long products like Bloom, Billet, bar bundles, Ingots & TMT bar bundles. Constructional feature:

Round:

• Body: - Steel; core:-Steel Forged • Bottom Non Magnetic Plate • Conductor: - Copper or Aluminum • Insulations:- Class ‘H’ or ‘C’ insulation as per customer’s Requirements

Rectangular:

• Body & Centre Pole( core ) : - High permeability steel • Bottom Non Magnetic Plate • End Plates Non Magnetic. • Coil: - Copper or Aluminum • Insulations:- Class ‘H’ or ‘C’ insulation as per customer’s Requirements.

All magnets are fitted with surge suppressor in the terminal box for protection against voltage surge due to accidental snapping of magnet supply cables/connections.

SAFETY FEATURES:

• Supplied voltage should be maintained to 220 VDC or 110 VDC as per specification. • CDF 50% should be maintained (5 Min OFF & 5 Min On). • Pushing of raw materials into hot furnace with the magnet should be avoided. • To maintain CDF we suggest you to buy control panel with the magnet which has duty cycle monitor and alarm so that CDF of 50% can be maintained

KAKKU HEAVY DUTY RECTANGULAR LIFTING ELECTRO MAGNETS: SERIES KRM-H & KRM-C Kakku heavy Duty Lifting Electro-magnet series KRM-H are specially designed to handle hot loads at temperature up to 600ºC whereas magnet series KRM-C are designed to lift loads in cold condition. These rectangular electro- magnets are designed to handle long loads such as rails, beams, billets, blooms & pipes etc. Usually two or three electro-magnets suspended from one traverse beam are employed to lift such long loads.

DESIGN AND CONSTRUCTIONAL FEATURES:

 The lifting electro-magnets series KRM are provided with high permeability cast steel shell. The frame of the electromagnet accommodates the coil, protected at the bottom with a non - magnetic plate to withstand the blows against loads being lifted. The pole pieces which are exposed to lifting pressures, are manufactured from special wear resistant steel. The coil is assembled within the electromagnets, such that it can resist shocks and vibrations. The gaps between shell and the coil are filled with a special heat-resistant Silicon Rubber compound to enhance the mechanical and electrical strength of the coil. The coils are manufactured from high conductivity annealed copper tape. Turn to turn insulation is suitable to withstand high temperatures.

 The non-magnetic plates are provided with sufficient insulation to protect the coils from the heat of the hot objects being lifted by the magnets. The terminal box is specially designed to protect the terminals from external damages. Each Lifting Magnet is provided with a device for voltage surge protection.

 When the electro-magnet works at higher than 50% duty factor, the voltage across the electro-magnet coil Should be decreased to the following value: 0.5 U = 1555/ (DFa) Where DFa = actual value of relative duty factor(DF).

TECHNICAL DATA:

Rated Voltage: 110 / 220V DC

Duty Factor: 65% or more

Windings: Copper

Class of Insulation: class – H / C

Other operating conditions: Height above sea level not over 2000 Mtrs.

Insulation Voltage: 660V

ORDERING DATA:  Specify type No and size considerations

 Shape Circular/ Rectangular

 Temperature of handling material (in ºC)

 Power Capacity and Voltage available

 Specify optional extras if any.

PRINCIPLE OF OPERATION

When the electro-magnet coil is energized, it is capable of lifting loads according to its design and the material used. The control panels supplied along-with the lifting magnets provides the reverse currents for demagnetization.

SAFETY FEATURES AND PRECAUTIONS

1) Supplied voltage should be maintained to 220 VDC or 110 VDC as per specification.

2) CDF 50% should be maintained (5 Min OFF & 5 Min On) or according to the specific duty cycle.

3) Pushing of raw materials into hot furnace with the magnet should be avoided.

4) To maintain CDF we suggest you to buy control panel with the magnet which has duty cycle monitor and alarm so that CDF of 50% can be maintained.

Specific information about lifting capacities of electro-magnets series KHM as obtained from particular test or specific instance in service use is as follows: TABLE A – Selection chart for Rectangular magnets lifting Cold objects KRM-C:

Magnet KW Size No. of Billets / Blooms, standard length 6 meter, to be Weight Weight of 2 type (110V (L X W) Lifted with 2 rectangular magnets. of each Magnets KRM- DC) (in mm) 100x100 130x13 160x160 200x20 250x25 Magnet with C 0 0 0 (Kgs) spreader Beam 12032 1.68 900x485 6 5 4 - - 850 2000 12042 1.98 1050x485 8 6 5 - - 950 2300 12052 2.2 1260x485 10 8 6 - - 1100 2600 13032 1.79 900x500 6 5 4 3 - 900 2100 13042 2.14 1050x500 8 6 5 4 - 1000 2400 13052 2.53 1260x500 10 8 6 5 - 1150 2700 14042 2.2 1060x530 8 6 5 4 3 1050 2500 14052 2.64 1300x530 10 8 6 5 4 1200 2800

TABLE B– Selection chart for rectangular magnets lifting hot objects having temperature up to 600 deg. C KRM-H: Magnet KW Size No. of Billets / Blooms, standard length 6 meter, to be Weight Weight of type (110 (L X W) Lifted with 2 rectangular magnets. of each 2 Magnets KRM-H V (in mm) 100x100 130x130 160x160 200x200 250x250 Magnet with DC) (Kgs) spreader beam 12022 1.65 800 x 485 5 4 3 - - 950 2300 12032 1.91 910x485 6 5 4 - - 1050 2500 12042 2.3 1050x500 8 6 5 - - 1200 2800 12052 2.74 1360x485 10 8 6 - - 1400 3200 13032 2.09 910x520 6 5 4 3 - 1060 2500 13042 2.47 1070x520 8 6 5 4 - 1190 2750 13052 3 1280x520 10 8 6 5 - 1360 3120 14042 2.89 1080x550 8 6 5 4 3 1200 2800 14052 3.43 1300x550 10 8 6 5 4 1400 3200

CASE STUDY: Process of designing Rectangular Magnet A general case is of the Rectangular Magnets used for lifting slag in large furnaces. These magnets have to be specifically created to not enough only lift weight, but also to be robust and resilient in the high temperature conditions. For a better understanding of the process, let us take an example of an order by Mr.Sharma (Name changed for privacy purposes).

 Mr. Sharma’s company orders for a lifting magnet for its furnace with a capacity of 1 ton.  The magnet thus designed will be capable of lifting approximately 700 kg at a time, so as to ensure no overflow happens.  The customer will also tell Kakku about his Crane’s Lifting Capacity. Mr. Sharma says that his factory has a 7.85kW capacity. The magnet will be designed to work at 70% of the given power, to amount for other appliances like lights, exhausts connected, which use up electricity too.  Mr. Sharma now has 2 choices for the magnet type:

(1) 50% Duty Cycle – 5 minutes on and 5 minutes off (2) 75% Duty Cycle – 7.5 minutes on and 2.5 minutes off

 The difference between the two cycles is that a magnet with a 75% Duty cycle will have a stronger magnetic strength (Ampere Ton/ mm2), however it is more expensive than a magnet with a 50% duty cycle.  The last piece of information that Mr. Sharma has to give us is whether an aluminum conductor will be used or a copper conductor. 60% of the total cost of the magnet is of the conductor. A copper conductor has a higher current density and a much higher half-life than an aluminum conductor, but correspondingly has a price 3 times of an aluminum conductor.  Mr. Sharma tells Kakku Industries that he would want a kW magnet and has voltage capacity of 110 V.

The data collected is as follows:

1. Power: 5.5kW 2. Voltage: 110 V 3. Current: 50A 4. Resistance: 2.2 ohms 5. Turns per coil: 118 6. No. of coil: 8 ; Total number of turns: 8 * 118 = 944 7. Cross Sectional Area (CSA): 26.64 mm2 8. Current Density = Current/ CSA = 50/26.64 = 1.87 A/mm2 9. Coil Outer Diameter = 910 mm 10. Coil Inner Diameter = 470 mm 11. Coil Thickness = 20 mm

Once the raw data is gathered, software (specially tailored for Kakku Industries) is used to calculate the required specifics from the data presented above. The actual calculations done by hand are attached in the annexure at the end. The software is programmed such to execute operations and calculations and give the result in a matter of seconds.

Once the design and dimensions of the magnet, its core and its insulations are finalized, the details are then sent to the factory in-charge for the magnet to be manufactured.

MANUFACTURING PROCESS OF LIFTING RECTANGULAR ELECTROMAGNET

1. MANUFACTURING PROCESS OF MAGNET SHELL OF RECTANGULAR MAGNET. 1. Cutting of plate as per drawing and dimension. 2. Fabrication will be done after cutting of plate and Magnet Shell steel body will be made as per approved drawing & dimensions of Rectangular Electromagnet.

2. MANUFACTURING PROCESS OF MAGNET CORE OF RECTANGULAR MAGNET

1. Electromagnet Core will be made by forged steel as per dimension and lifting capacity of Magnet.

3. MANUFACTURING PROCESS OF ELECTROMAGNET COIL.

1. As per Ohms Law (V= IR) and Current density of the conductor Material, we have to design and calculate the size of conductor (Copper / Aluminum) (Done above) 2. Winding of conductor has to be done as per calculation of Number of Turns & layers. 3. In between the layers of coil we will apply insulation paper of class C/ Class H insulation. 4. After completion of coil winding, Varnishing of the coil will be done. 5. After varnishing, Coil will be shifted into Oven for baking process at the temperature of 120 Degree Celsius for 12 hours approx. 6. After baking of coil, leave it for 2-3 hours for cooling. 7. After cooling of coil, insulation will done with Flexible Mica sheet & Glass tape.

4. ASSEMBLY OF RECTANGULAR ELECTROMAGNET

1. Fixing of core to the Magnet steel Shell by welding or bolting method. 2. Before assembly of coil into Magnet Shell, Insulation will be done on Magnet Core & bottom of Magnet Shell. 3. Assembly of coil has to be done on Magnet core. 4. With help of Silver brazing Rod we will connect Silicon Cable with both ends of coil and it will comes to terminal box for power supply. 5. After Assembly of coil into Magnet Shell, we will put the same into electric oven for removal of moisture from insulation at 120 degree Celsius for 12 hours approx. 6. After removal of moisture to the Magnet, Megger (IR) Value will be checked & it should not be less than 50 Mega Ohm. 7. After we got Megger value, filling of silicon rubber Compound has to be done.

5. SEALING OF MAGNET

1. Before sealing of Magnet power supply is to be given into Magnet for checking of IR value & it should be more than 50 Mega Ohm. 2. After that we will apply 20 mm insulation on top Magnet core levels. 3. Welding of M.S. Shim Plate on core with Magnet Shell. 4. Fixing of Non-Magnetic bumping Plate with support of centre pole steel plate through bolt. 5. Chain welding of Non-Magnetic Bumping Plate with top side of Magnet Shell 6. Centre pole steel plate fixing on Forged core with HT Bolts. 7. Outgoing Silicon cable to be fixed in Terminal Box. 8. Fixing of Surge Suppressor in terminal box for protection of Magnet from High Voltage. 9. After completion, Silicon compound will be filled in Terminal Box. 10. After complete sealing of Magnet, Painting and finishing will be done.

The magnet is then packaged and shipped to the customer. Regular checks and maintenance services are provided.

The schematic diagram of a rectangular lid lifting magnet

Rectangular Magnet manufacturing in Process

Magnet making in progress

KAKKU HEAVY DUTY CIRCULAR LIFTING ELECTRO MAGNETS- SERIES A & C Kakku Heavy Duty Circular Lifting Electro-magnet are designed for handling steel and cast iron objects like plates, pigs scraps, sponge iron, solid ingots etc.

DESIGN & CONSTRUCTIONAL FEATURES  The lifting electro-magnets are provided with high permeability cast / fabricated steel shell.  The frame of the electro-magnet accommodates the coil, protected at the bottom with a non - magnetic plate to withstand the blows against loads being lifted. The pole pieces which are exposed to lifting pressures are manufactured from special wear resistant steel.  The coil is assembled within the electro-magnets, such that it can resist shocks and vibrations. The gaps between shell and the coil are filled with a special heat-resistant Silicon Rubber compound to enhance the mechanical and electrical strength of the coil. The coils are manufactured from high conductivity annealed copper tape. Turn to turn insulation is suitable to withstand high temperatures.  The non-magnetic plates are provided with sufficient insulation to protect the coils from the heat of the hot objects being lifted by the magnets. The terminal box is specially designed to protect the terminals from external damages. Each Lifting Magnet is provided with a device for voltage surge protection.  When the electro-magnet works at higher than 65% duty factor, the voltage across the electro-magnet coil should be decreased to the following value: 0.5 U = 1555/ (DFa) Where DFa = actual value of relative duty factor(DF).

TECHNICAL DATA

Rated Voltage: 220V DC

Duty Factor: 50% or 75%

Windings: Copper/Aluminum

Class of Insulation: class – H / C

Other operating conditions: Height above sea level not over 2000 Meters.

Insulation Voltage: 660V

ORDERING DATA Specify type No and size considerations

Shape Circular/ Rectangular

Temperature of handling material (in ºC)

Power Capacity and Voltage available

Specify optional extras if any.

PRINCIPLE OF OPERATION

When the electro-magnet coil is energised, it is capable of lifting loads as indicated in Table A. The control panels supplied along-with the lifting magnets provides the reverse currents for demagnetisation.

SAFETY FEATURES AND PRECAUTIONS 1) Supplied voltage should be maintained to 220 VDC or 110 VDC as per specification.

2) CDF 50% should be maintained (5 Min OFF & 5 Min On) or according to the specific duty cycle.

3) Pushing of raw materials into hot furnace with the magnet should be avoided.

4) To maintain CDF we suggest you to buy control panel with the magnet which has duty cycle monitor and alarm so that CDF of 50% can be maintained.

TABLE A- MILL DUTY ALUMINIUM WOUND MAGNETS KW Magnet Supply (Cold) Dimensions Lifting Capacity Kgs. (approx) Magnet Duty Type Volts (V) Approx. (Approx.) . Weight Factor DC` (Kgs.- Approx

OD H Sponge Heavy Pig Iron Iron melting Scrap A-112 110 5.5 1220 1350 250 500 575 1650 50% A-113 110 9.2 1320 1350 350 700 805 1900 50% A-115 230 12.0 1475 1500 480 960 1104 2100 50% A-116 230 13.2 1650 1550 525 1050 1208 3200 50% A-116Y 230 17.0 1650 1600 800 1600 1840 3900 50% A-118X 230 18.0 1850 1650 1000 2000 2300 4700 50% A-119X 230 23.0 1950 1700 1200 2400 2760 5700 50%

TABLE B- MILL DUTY COPPER WOUND MAGNETS Magnet Supply KW Dimensions Lifting Capacity Lgs. (approx) Magnet Duty Type Volts (V) (Cold) (Approx.) . Weight Factor DC` Approx. (Kgs.- Approx OD H Sponge Heavy Pig Iron Iron melting Scrap C-116 220 10.87 1620 1600 500 1000 1150 3100 50% C-116X 220 14.5 1650 1600 725 1450 1668 3600 50% C-118 220 18.9 1850 1650 900 1800 2070 4200 50% C-118X 220 19.6 1870 1650 1000 2000 2300 4500 50% C-118XX 220 23.3 1870 1650 1200 2400 2760 5400 50% C-119X 220 27.5 1930 1650 1500 3000 3450 6600 50% C-316X 220 16.5 1670 1600 850 1700 1955 4200 50%

MANUFACTURING PROCESS OF LIFTING CIRCULAR ELECTROMAGNET

1. MANUFACTURING PROCESS OF MAGNET SHELL OF CIRCULAR MAGNET

 Steel casting of Shell as per diameter or cutting of plate for fabricated design as customer requirement.  Machining of Steel casting or Fabricated Shell as per approved drawing of Circular Electromagnet.

2. MANUFACTURING PROCESS OF MAGNET CORE OF CIRCULAR MAGNET

 Electromagnet Core will be made by forged steel as per dimension and lifting capacity of Circular Magnet

3. MANUFACTURING PROCESS OF CIRCULAR ELECTROMAGNET COIL

 As per Ohms Law (V= IR) and Current density of the conductor Material, we have to design and calculate the size of conductor (Copper / Aluminium).  Winding of conductor has to be done as per calculation of Number of Turns, Layer and Number of Coils as per design.  In between layer of coil we will apply insulation paper of class C/ Class H insulation.  After completion of coil winding, Varnishing of coil will be done.  After varnishing, Coil will be shifted into Oven for baking process at the temperature of 120 Degree Celsius for 12 hours approx.  After baking of coil, leave it for 2-3 hours for cooling.  After cooling of coil, insulation will done with Glass tape.

4. ASSEMBLY OF CIRCULAR ELECTROMAGNET

 Fixing of core to the Magnet Steel Casting/Fabricated Shell by welding or bolting method.  Before assembly of coil into Magnet Shell, Insulation will be done on Magnet Core & bottom of Magnet Shell.  Assembly of coil has to be done on Magnet core.  With help of Silver brazing Rod we will connect Silicon Cable with both ends of coil and it will comes to terminal box for power supply.  After Assembly of coil into Magnet Shell, we will put the same into electric oven for removal of moisture from insulation at 120 degree Celsius for 12 hours approx.  After removal of moisture to the Magnet, Megger (IR) Value will be checked & it should not be less than 200 Mega Ohm.  After we got Megger value, filling of silicon rubber Compound has to be done.

5. SEALING OF MAGNET

 Before sealing of Magnet power supply is to be given into Magnet for checking of IR value & it should be more than 200 Mega Ohm.  After that we will apply 20 mm insulation on top Magnet core levels.  Welding of M.S. Shim Plate on core with Magnet Shell.  Fixing of Non-Magnetic bumping Plate with support of Shell and Core.  Continuous welding of Non-Magnetic Bumping Plate with top side of Magnet Shell  Outgoing Silicon cable to be fixed in Terminal Box.  Fixing of Surge Suppressor in terminal box for protection of Magnet from High Voltage.  After completion, Silicon compound will be filled in Terminal Box.  After complete sealing of Magnet, Painting and finishing will be done.

The magnet is then packaged and shipped to the customer. Regular checks and maintenance services are provided. The schematic diagram of a lid lifting circular magnet is provided for your reference.

Circular magnet making in progress

TESTING OF THE FINISHED ELECTROMAGNET The following tests are done for quality control and maintaining consistency across all the products:

(1) MEGGER TESTING: The Megger Machine is used to find the Megger number of the magnet, which is an indication of the amount of moisture present in the insulation coating applied on the magnet. The Megger Number should be less than 200 for the magnet to function as desired. (2) LOAD TESTING: The lifting capacity of the magnet is checked by the Load Test, wherein varying amounts of Sponge Iron is lifted by the Magnet. (3) RESISTANCE TEST: The resistance of the magnet is checked by using a Resistance Bridge. The result should come according to the calculated values. (4) HIGH VOLTAGE TEST: High Voltages are applied on the magnet to check its voltage bearing capacity.

SAMPLE TEST REPORT

VOLTAGE TEST BEING DONE ON FINISHED PRODUCT

HIGH VOLTAGE TEST : The electromagnet is subjected to multiple different voltages, going even as high as 5000 V for upto 2 minutes to check the Voltage Resiliency of the Magnet.

Test at the Standard Voltage of 220 V

LOAD TEST BEEN PERFORMED ON CIRCULAR MAGNET

LOAD TESTING TEST: The electromagnet’s load carrying capacity is tested by using Sponge Iron as the weight to be lifted. This ensures that the magnet produced can carry enough load.

ACKNOWLEDGEMENT

I cannot express enough thanks to Mr. Rajesh Bahadur (Managaing Director); Mr Amit Bahadur (Director); Mr. Sumit Bahadur (Director) for their continued support and encouragement: I offer my sincere appreciation for the learning opportunities provided by them.

The completion of this case study could not have been accomplished without the support of the engineers at Kakku Industries – Mr. Krishna, Mr. Prashant and Mr. Neeraj. My heatrtfelt gratitude for guiding and helping me in my case study.

APPENDIX : (1) Scanned copy of hand written calculation done for the manufacturing of Rectangular Magnet