Welding equipments

Welding equipment's is the tools used in the welding
The following equipment's used in the welding
1. Power Source (AC or DC)
2. Electrode Holder
3. Welding Cables
4. Ground Clamp
5. Welding Electrodes
6. Welding Helmets & Hand Shield
7. Protective Cloths
8. Finishing tools – Wire brush, Chipping Hammers.

1. WELDING EQUIPMENTS ER. PEEYUSH CHAUHAN ASSISTANT PROFESSOR DEPARTMENT OF MECHANICAL ENGINEERING

2. “ Welding equipment's is the tools used in the welding” The following equipment's used in the welding- 1. Power Source (AC or DC) 2. Electrode Holder 3. Welding Cables 4. Ground Clamp 5. Welding Electrodes 6. Welding Helmets & Hand Shield 7. Protective Cloths 8. Finishing tools – Wire brush, Chipping Hammers. INTRODUCTION

3. POWER SOURCE

4. W elding power source is designed to change high voltage low ampere current into a safe low voltage (Between 50-100 volts) heavy current (above 500 amperes ). Power Sources for Arc Welding transform the power from the grid to controlled values of voltage and of current suitable to the intended uses. The power source are generally three types- 1. Direct current power sources 2. Alternate Current power source 3. Combination power source POWER SOURCE

5. Selection of Power Sources- 1. Availability of power (AC or DC) 2. Available floor space. 3. Location of operation ( Plant or Field) 4. Personal available for maintenance 5. Versatility of equipment's 6. Required output 7. Initial cost & running cost 8. Duty cycle 9. Efficiency 10. Types of work ( Heavy or Light)

6. 1. Direct Current Power Sources- 1. DC Generator Set- A DC welding generator produce direct current in either straight or reverse polarity. A DC generator is powered either by electric motor or a diesel engine. The current supplied by the DC generator is created by an armature rotating in electric field. The armature is rotating by the electric motor or an engine. The generator are designed to rotate at speeds of 1500, 1800 or 3600 rpm to give optimum current value. Generator supplied the voltages usually in the range from 15 to 45 volts across the arc.

7. Following advantages of DC generator set are- 1. Straight as well as reverse polarity can be employed. 2. Welding can be carried out in all positions. 3. Nearly all ferrous & non-ferrous metal can be welded. 4. Generator output is not affected by normal variation in power line voltage. Following disadvantages of DC generator set are- 1. Highly initial cost 2. Higher maintenance cost 3. Noisy machine operations.

8. 2. AC-DC Rectifiers- A AC-DC rectifiers can supply any types of current. This type of machine essentially transformers containing a electrical device known as rectifier which change AC to DC. The rectifier may consists of metal plates coated with selenium compound or silicon didoes, each unit having a special property of allowing the current flow in one direction only. A rectifier unit is installed with a fan to cool the transformer. Its designed for a single phase or three phase power supply.

9. Following advantages of AC-DC rectifier are- 1. They can provide both straight & reverse polarity. 2. They possess all the advantages of an AC transformer. 3. They have good performance at low welding currents. 4. The current in AC-DC rectifier easily controlled by remote. Following disadvantages of AC-DC rectifier are- 1. The life of selenium plate is limited to about 7 years under normal usage.

10. 3. Thyristor-Controlled rectifier- A thyristor controlled rectifier use instead of conventional rectifier in welding machine. A thyristor is a solid state device which allows current to flow in one direction, i.e., its behave as a normal rectifier. It’s also known as silicon control rectifier. Basically , thyristor is a three-terminal, four-layer semiconductor device consisting of alternate layers of p-type and n-type material. Thyristor controlled rectifier generally use for SMAW & TIG welding.

11. 4. Inverter System- Since the advent of high-power semiconductors such as the insulated gate bipolar transistor (IGBT), it is now possible to build a switched-mode power supply capable of coping with the high loads of arc welding. These designs are known as inverter welding units. It generally first rectify the utility AC power to DC; then switch (invert) the DC power into a stepdown transformer to produce the desired welding voltage or current. The switching frequency is typically 10 kHz or higher.

12. 2 . Alternative Current Power Sources- 1. AC Generator Set- An AC generator consists of an alternator that provides welding current. Its driven by an AC motor or diesel engine. A typical alternator design normally places the magnetic field coils on the rotor & the armature coils in the stator. An AC generator may deliver current at normal frequency (60 Hz) or high. The frequency of the output welding current is controlled by the speed of rotation of the rotor assembly & by the number of poles in the alternator.

13. 2. AC Transformer- A welding transformer changes high voltage, low amperage power to low voltage, high amperage welding power. An AC transformer is the least expensive, lightest & smallest welding machine. It takes power directly from the main & transforms it to the voltage/current required for welding. Since AC passes through zero twice every cycle, it means that there are two period in every cycle when the welding current is zero during which the arc would extinguish & make continuous welding difficult. This difficulty is removed by- 1. Building in automatic Arc Stabilization in welder windings.

14. 2. Electrode coating which produce complete ionization in the arc stream & keep the arc igniting as the current passes through zero. Advantage of AC Transformer- 1. Its least expensive, lightest & smallest welding machine. 2. No Arc blow generate during welding. 3. Workpiece do not get magnetize as do in DC. 4. Low operating & maintenance cost. 5. Noiseless operation because no moving part in transformer. 6. Overall electrical efficiency is high.

15. Disadvantage of AC Transformer- 1. Polarity can’t be change. 2. In AC starting the arc is more difficult than with DC. 3. Poor power factor is inherent in use of transformer of the constant current type. Applications- 1. In flux shielded metal arc welding. 2. In industries (200 ampere- 500 ampere) 3. Heavy gauge steel.

16. WELDING CABLES

17. “Welding cables are use for supply the current in the electrode & workpiece through power source.” In the welding two cables are use- 1. Electrode Lead – It join the electrode holder or electrode to the welding power source. 2. Ground Lead- It join the workpiece to the welding power source. A welding cables or leads are well insulated with rubber & a woven, fabric reinforcing layer. Above the insulation is an outer jacket of a durable layer of rubber or neoprene. WELDING CABLES

18. Welding cables are produced in several sizes. The smaller the number, the larger the dimeter of lead. The size of the welding leads is selected depending upon the capacity of welding machine stated in ampere & maximum length of cable. For Example- 200 Amps welding machine with 60% duty cycle use 2 number cable for distance up to 50 meters. Welding cable is made from stranded bundles of copper wire tightly packed and insulated. Welding cable usually comes with rubber insulation, typically either Neoprene or Ethylene Propylene Diene Monomer (EPDM) rubber , and is designed to be fire (small sparks), water, oil, and abrasion resistant.

19. Electrical cable is typically categorized by an AWG (American Wire Gauge) size, where the smaller diameter cable has a larger number. Cable sizes between #4 and #4/0 are typically used for welding cable . AWG sizes have three numbers, for example, "2 AWG 625/30" This means that the welding cable has a total cross sectional area of 2 AWG and is made from 625 strands of 30 AWG wire.

20. Connection for leads- The ground lead connected to the workpiece by- 1. By Bolt. 2. By C-clamp 3. By Tack. 4. By ground Clamp The electrode leads is to connected to the welding machine by Lugs. These lugs are made of a cast copper alloy & may be covered with fiber insulation layer. Lugs are attached to the welding machine cables by soldering or mechanical methods such as crimping.

21. Cable connectors are fitting especially designed for joining two or more length of welding cable to obtain a long cable. It can be easily connect or disconnect.

22. ELECTRODE HOLDER

23. “An electrode holder, commonly called a stinger, is a clamping device for holding the electrode securely in any position.” Or “ Electrode holder is a device used for mechanically holding the electrode & conducting current to it .” The electrode holder have following parts- 1. Jaw 2. Jaw Spreading Lever 3. Insulator 4. Spring 5. Heat Shield 6. Handle ELECTRODE HOLDER

24. The electrode jaw are made to hold the bare end of the electrode in either in vertical or angular position. For this purpose grooves are cut into the jaw. The electrode lead is firmly fastened to the electrodes holder with a lug or mechanical connections with insulator to protect the operator against electrical shocks. The electrode holder are generally matched to the size of lead & amperage. The electrode holder are generally available in size that range from 150 Amp. t o 500 Amp . There are following requirements of a good electrode holder- 1. It should be light to minimize fatigue incurred by the welder. 2. It should not be heat up too rapidly.

25. The electrode jaw are made to hold the bare end of the electrode in either in vertical or angular position. For this purpose grooves are cut into the jaw. The electrode lead is firmly fastened to the electrodes holder with a lug or mechanical connections with insulator to protect the operator against electrical shocks. The electrode holder are generally matched to the size of lead & amperage. The electrode holder are generally available in size that range from 150 Amp. t o 500 Amp. There are following requirements of a good electrode holder- 1. It should be light to minimize fatigue incurred by the welder. 2. It should not be heat up too rapidly.

26. 3. It should produce a balanced feeling when held in the operator’s hand, with the cable draped over the operator’s arm & with the average length of metallic electrode in the holder. 4. It should receive & eject the electrode rapidly. 5. All exposed surface of the electrode holder including jaws should be protected by insulator. 6. For the ease of welder the handle of the electrode holder may be water cooled when welding heavy worked.

27. ELECTRODE

28. “An electrode is a piece of wire or a rod ( of a metal or alloy) with or without flux covering, which carries current for welding. At one end it’s gripped in a holder & an arc is set up at other.” Or An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). The word was coined by William Whewell at the request of the scientist Michael Faraday from two Greek words: elektron , meaning amber (from which the word electricity is derived), and hodos , a way. The electrophore , invented by Johan Wilcke , was an early version of an electrode used to study static electricity . ELECTRODE

29. Welding Electrode Non Consumable Consumable (Refractory) (Metallic) Carbon Tungsten Bare Flux Covered Or Graphite Electrodes Electrodes Electrodes Electrodes Pure Thoriated Zirconiated DC AC Tungsten Tungsten Tungsten Electrode Electrode DCSP DCRP

30. Flux Covered Electrode Sizes Positions Coating All Position Low Length Diameter Flat Medium 250 mm 1.5 Horizontal Heavy 300 mm 2.0 Vertical Cellulose 350 mm 2.5 Overhead Iron Powder 450 mm 3.15/3.25 4,5,6.3 mm etc. Ferrous Nonferrous Cast Alloy High Carbon Al Al Lead Phosphor Iron Steel Steel Bronze Bronze Bronze

31. 1. Non-consumable Electrode- It’s made of high melting points materials like carbon (6700 F), pure tungsten (6150 F) or alloy tungsten. These electrodes don’t melt during welding. These electrode length goes on decreasing with the passage of time because of vaporization & oxidation of the electrode materials during welding. Non consumable electrodes are copper coated carbon & graphite electrode because of copper coating increase the electrical conductivity or current conducting capacity of the electrodes. Carbon or graphite electrodes ranging from 2 mm to 15 mm are employed for welding purposes.

32. Alloying pure tungsten increase emissivity, resistance to contamination, arc stability & electrode life. Tungsten/alloy tungsten electrodes ranging from 0.5 mm to 6 mm diameter are commonly used during welding. Tungsten & alloy tungsten electrodes are generally used with DCSP. Electrode Color Classification Pure Tungsten Green 1% Thorium Yellow 2% Thorium Red 0.3 -0.5% Zirconium Brown

33. 2. C onsumable Electrode- It’s made of low melting point electrodes made up of different metals & their alloys. The electrode itself adds filler metals. Types of Consumable Electrodes- Consumable Electrodes are following types- 1. Bare Electrodes- It’s consist of metal or alloy wire without any flux coating. Bare electrodes are used for welding manganese steel and other purposes where a coated electrode is not required or is undesirable. 2. Light Coated Electrodes- It’s consists a coating factor approximately 1.25. Example- Citobest electrode of advani oerlikon (A.O).

34. 3. Medium Coated Electrodes- It’s consists a coating factor approximately 1.45. Example- Overcord -C, (A.O) 4. Heavy Coated Electrodes- It’s consists a coating factor between 1.6 & 2.2. It produce a deeper penetration. Example- Citofine (A.O). Covered Electrode- When molten metal is exposed to air, it absorbs oxygen and nitrogen, and becomes brittle or is otherwise adversely affected. A slag cover is needed to protect molten or solidifying weld metal from the atmosphere. This cover can be obtained from the electrode coating . A Covered electrode consists of a flux material coated on the core wire.

35. Manufacture Process of Electrodes- There are two methods of applying flux coating on the core wire 1. Dipping 2. Extrusion Process 1. Dipping Method- I n this method core wire are cut into definite length & clamp vertically in fixture & dipped in a bath of molten flux. When a suitable thickness of the flux gets adhered to the core wire, the fixture is raised & the flux is allowed to dry.

36. 2 . Extrusion Method- I n this method coating ingredients are mixed up in desired quantities, binder (sodium silicate) is added & the resultant mass is brought in the form of a thick, viscous, stiff paste. This paste is shaped in the form of a cylinder which is fed into the extrusion press. The core wire & thick paste of flux simultaneously under pressure pass though a die, thus attaching the flux coating on the core wire. The gripping end of electrode is removed by electrically rotate wire brush.

37. Flux ingredient & their Function Flux Ingredient Primary Function Secondary Function Cellulose Gas Generation De-oxidation, Strengthening coatings Clay Slag Formation Arc Stability Taic Slag Formation Titanium Oxide Arc Stability, Slag Formation Ilmenite Slag Formation Arc stability Iron Oxide Slag Formation, Oxidation Arc stability Lime Carbonate Gas Generation Arc stability, Oxidation, Slag formation

38. Flux Ingredient Primary Function Secondary Function Ferromanganese De-oxidation, Alloying Slag Formation Manganese Dioxide Oxidation Slag Formation Silica Sand Slag Formation Potassium Silicate Binding Coatings, Arc Stability, Slag Formation Sodium Silicate Binding Coatings, Arc Stability, Slag Formation

39. Selection of Electrodes- 1. Chemical Composition of the base metal. 2. Thickness of the workpiece. 3. Nature of electrode coating (Cellulose, Rutile & low hydrogen etc.) & metal losses due to volatilization & spatter. 4. Positions ( Flat, Horizontal, Vertical, Overhead) in which welding is to be carried out. 5. Types of joint ( lap, butt, fillet etc.) & number of runs. 6. Types of power source ( AC or DC) Available. 7. Types of polarities (DCSP or DCRP). 8. Weld bead geometry & shape of the weld bead. 9. Surface finish & quality of weld metal. 10. Cost of the electrode.

40. Electrode Coding- According to Indian (IS) System- L X X X X X X L 1 st 1 st 2 nd 3 rd 4 th 5 th 6 th Last Letter Digits Letter 1 st Letter – It can be E or R. E= Solid extruded Electrode R= Reinforcement extruded Electrode 1 st Digit – It indicates the class of covering. It’s can be 1,2,3,4,5,6 or 9.

41. 1 st Digit – It indicates the class of covering. It’s can be 1,2,3,4,5,6 or 9. 1= High Cellulose Content. 2= High Titania Content resulting fairly viscous slag. 3= Appreciable Titania Content resulting in a fluid slag. 4= High Iron & Mn Oxide or Silicates Contents resulting in inflated slag. 5= High Iron & Mn Oxide or Silicates Contents resulting in a heavy solid slag. 6= Highly calcium carbonate & fluoride content. 9= A ny other types of covering . 2 nd Digit – It indicates positions in which electrode can weld satisfactory. It’s can be 0,1,2,3,4 or 9.

42. 0 & 1= All positions (Flat, Horizontal, Vertical & overhead) 2= Flat & horizontal. 3= Flat only. 4= Flat & Horizontal fillet positions. 9= Not Classified. 3 rd Digit – It indicates the current, polarity & open circuit voltage of welding power source. It’s can be 0,1,2,3,4,5,6,7,9. 0 = DC+ i.e. DCRP 1 = DC+, A90 i.e. DCRP or AC with OC voltage over 90 volts. 2 = DC-, A70 3 = DC-, A50 4 = DC+, A70

43. 5 = D± , A90 6 = D± , A70 7 = D± , A50 9 = Not Classified. 4 th & 5 th Digit – It indicates the range of tensile strength & minimum yield strength. 6 th Digit – It indicates the percentage elongation & impact value. Last Letter – It’s can be P,H,J,K or L. P = Deep penetration electrode. H = Hydrogen controlled electrode J= Electrode powder coating & metal recovery 110-130% K = Electrode powder coating & metal recovery 130-150 %

44. L= Electrode powder coating & metal recovery more than150% Example- E307411P E= Extruded electrode 3= Covering contains appreciable amount of Titania, a fluid slag. 0= All position electrode. 7= DCSP, DCRP or AC power source with OC voltage 50. 4= Tensile strength 410 N/mm 2 to 510 N/mm 2 1= Minimum Yield strength 330 N/mm 2 1=Minimum percentage elongation of weld metal is 20% of 5.65 S where S is cross section area of specimen. P= Deep penetration

45. HAND SHIELD & HELMETS

46. “ Hand shield is a protective device protecting the face & neck of the operator. A hand shield in the hand of the welder & equipped with a suitable filter lens.” A hand shield is a type of welder’s mask hold in one hand. Hand shields or helmets provide eye protection by using an assembly of components : 1. Helmet shell - must be opaque to light and resistant to impact, heat and electricity. 2. Outer cover plate- It’s made of polycarbonate plastic which protects from radiation, impact and scratches . HAND SHIELD & HELMETS

47. 3. Filter lens- It’s made of glass containing a filler which reduces the amount of light passing through to the eyes. Filters are available in different shade numbers ranging from 2 to 14. The higher the number, the darker the filter and the less light passes through the lens. 4. Clear retainer lens- It’s made of plastic prevents any broken pieces of the filter lens from reaching the eye. 5. Gasket- It’s made of heat insulating material between the cover lens and the filter lens protects the lens from sudden heat changes which could cause it to break. In some models the heat insulation is provided by the frame mount instead of a separate gasket.

48. “ Helmet is a protective device protecting the face, neck & head of the operator & equipped with a suitable filter lens .” Or A welding helmet is a type of headgear used when performing certain types of welding to protect the eyes, face and neck from flash burn, ultraviolet light, sparks, infrared light, and heat . Welding helmets are most commonly used with arc welding processes such as shielded metal arc welding, gas tungsten arc welding, and gas metal arc welding. They are necessary to prevent arc eye, a painful condition where the cornea is inflamed. Welding helmets can also prevent retina burns, which can lead to a loss of vision. HELMETS

49. The modern welding helmet used today was first introduced in 1937 by Willson Products . Most welding helmets include a window covered with a filter called a lens shade, through which the welder can see to work. In most helmets, the window may be made of tinted glass, tinted plastic, or a variable-density filter made from a pair of polarized lenses. Different lens shades are needed for different welding processes. For example MIG and TIG welding are low-intensity processes, so a lighter lens shade will be preferred.

50. Type of Welding Amperage Lens Shade TIG – Mild Steel 5 to 20 Shade 9 TIG – Mild Steel 20 to 30 Shade 10 TIG – Mild Steel 30 to 100 Shade 11 TIG – Mild Steel 100 to 150 Shade 12 TIG – Mild Steel 150 to 250 Shade 13

51. Type of Welding Amperage Lens Shade MIG – Aluminium 80 to 100 Shade 10 MIG – Aluminium 100 to 175 Shade 11 MIG – Aluminium 175 to 250 Shade 12 MIG – Aluminium 250 to 350 Shade 13

52. Type of Welding Amperage Lens Shade MIG – Flux Core 125 to 175 Shade 10 MIG – Flux Core 175 to 225 Shade 11 MIG – Flux Core 225 to 275 Shade 12 MIG – Flux Core 275 to 350 Shade 13

53. Type of Welding Amperage Lens Shade MIG – Mild Steel 80 to 100 Shade 10 MIG – Mild Steel 100 to 175 Shade 11 MIG – Mild Steel 175 to 300 Shade 12 MIG – Mild Steel 300 to 500 Shade 13

54. Type of Welding Amperage Lens Shade Plasma Welding 10 to 15 Shade 9 Plasma Welding 15 to 30 Shade 10

55. PROTECTIVE CLOTHING

56. The protective clothing protect the limbs of the welder against burning by molten metal, molten flux spatters & sparks.” The protective clothes are following types- 1. Apron 2. Gloves 3. Sleeves 4. Cape & Cap 5. Shoes 1. Apron- The apron provides protection to the clothes of the welder. It’s made of chrome leather. It offer best protection against hot spattering particles. PROTECTIVE CLOTHING

57. Welding Apron Welding Gloves

58. 2 . Gloves- The gloves protect the hand of the welder from ultraviolet rays & spattering hot metal. The gloves are generally made of leather or a combination of cloth & asbestos. 3. Sleeve- The sleeve is used for protecting the hands of the welder. 4. Cape & Cap- The cape protect the shoulders & arms of the welder & t he cap is employed to protect the head & hair of welder. 5. Shoes- The shoes are protect the feet of the welder from dropping molten metals.

59. Welding Sleeves Welding Cape

60. Welding Shoes Welding Cap

61. WELD BEAD CELANING ACCESSORIES

62. “The weld bead cleaning accessories are generally used for cleaning the weld bead.” Following weld bead cleaning accessories are used- 1. Chipping Hammer 2. Wire Brush 1. Chipping Hammer- The chipping hammer is chisel shaped & is pointed on one end to aid in the removal of slag from over the weld bead. 2. Wire Brush- The wire brush made up of stiff steel wire embedded in wood remove small particles of slag from weld bead after the chipping hammer has done its job. WELD BEAD CLEANING ACCESSORIES

63. The wire brush also used to clean the surface of the base metal of rust, oil scale, paint etc. before the welding operation so that resulting welds are of good quality.

64. Welding Hammer Welding Wire Brush