SMAW(Stick Welding)Chapter 5
*SMAW PrinciplesThe American Welding Society defines SMAW as Shielded Metal Arc WeldingSMAW:Is commonly known as Stick welding or manual arc welding Is the most widely used arc welding process in the worldCan be used to weld most common metals and alloys
*SMAW Welding CircuitCurrent flows through the electrode cable, to the electrode holder, through the electrode, and across the arcOn the work side of the arc, the current flows through the base material to the work clamp and back to the welding machine
*SMAW ProcessLets take a little closer look at the SMAW process1Travel directionElectrodeArc2Weld Puddle3Shielding Gas4Solidified Weld Metal5Slag6
*Application ActivityLets review the SMW process 1 = __________
2 = __________
3 = __________
4 = __________
5 = __________
6 = __________
*1- The Electrode Is a consumable - it gets melted during the welding processIs composed of two partsCore Rod (Metal Filler)Carries welding current Becomes part of the weldFlux Coating Produces a shielding gasCan provide additional filler Forms a slag
*2- The ArcAn arc occurs when the electrode comes in contact with the work-piece and completes the circuit like turning on a light!The electric arc is established in the space between the end of the electrode and the workThe arc reaches temperatures of 10,000F which melts the electrode and base materialCan you identify the weld joint and position being used?
*3- Weld PuddleAs the core rod, flux coating, and work pieces heat up and melt, they form a pool of molten material called a weld puddle The weld puddle is what a welder watches and manipulates while welding1/8 E6013 at 125 Amps AC
*4- Shielding GasA shielding gas is formed when the flux coating melts.This protects the weld puddle from the atmosphere preventing contamination during the molten state
The shielding gas protects the molten puddle from the atmosphere while stabilizing the arc
*5- Solidified Weld MetalAs the molten weld puddle solidifies, it forms a joint or connection between two pieces of base materialWhen done properly on steel, it results in a weld stronger than the surrounding base metal
*6- SlagSlag is a combination of the flux coating and impurities from the base metal that float to the surface of the weld. Slag quickly solidifies to form a solid coatingThe slag also slows the cooling rate of the weld The slag can be chipped away and cleaned with a wire brush when hardThis welder chips the slag off of a weld during the repair of railroad tracks
A complete SMAW StationA complete shielded metal arc welding station consists of:A Welding MachineAn Electrode LeadAn Electrode HolderA Workpiece LeadA Workpiece Ground Clamp
Welding LeadsWelding Leads: large diameter, super flexible leads (cables) are used to carry current from the welding machine to the work and back.Electrode Lead: The lead from the machine to the electrode holder.Work piece lead or ground lead: The lead from the work to the machine.Leads are well-insulated with rubber and a woven fabric reinforcing layer.Leads are subjected to considerable wear and should be checked periodically for breaks in the insulation.*
Welding LeadsLeads are produced in several sizes.The smaller the number, the larger the diameter.The lead must be flexible to permit easy installation of the cable, and to reduce the strain on the arc welders hand when welding.To produce this flexibility as many as 800 2500 fine wires are used in each cable.The SAME diameter electric cable must be used on both the electrode and work piece leads.The length of the lead has considerable effect on the size to be used for certain capacity machines.Use short leads to minimize current loss due to the lead resistance.*
Electrode HoldersElectrode Holder: the part of the arc welding equipment held by the operator when welding. Holds the electrode.Many different styles and models are available, but they all have similar characteristics.*
Weld-Cleaning EquipmentIt is very important that the base metals in weldments be cleaned prior to welding.It is difficult to weld dirty or corroded surfaces.Resulting welds will normally be of poor quality.Weldments: A unit composed of an assemblage of pieces welded together.
Chipping HammerChipping hammers are often double-ended.One end is shaped like a chisel for general chipping.The other end is shaped like a pick, for reaching into corners and narrow spaces.
HeadgearArc welding requires the use of special equipment to protect skin surfaces, such as the hands, face and eyes.The Occupational Safety and Health Administration (OSHA) requires the use of a hard hat with the arc welding helmet on construction sites.
Arc Welding HelmetAn Arc Welding Helmet is used to protect the face and eyes.It is mounted and supported on the headMade of fiber, plastic or fiberglass and is formed in a shape that covers the front half of the head.Headbands on the helmets are adjustableThere is an tension adjustment that keeps the helmet up.You can adjust the tension so a slight nod of the head will allow the helmet to rotate down over your face
Welding Helmet Lenses A good grade of colored arc welding filter lens will remove approximately 99.5% of the infrared rays and 99.75% of the ultraviolet rays from the light emitted by the arc.U.S. Bureau of Standards developed recommended shades for various arc welding applications.Shade number 10, 12 and 14 are the common ones used for SMAW.The higher the shade number, the lower the transmission of infrared or ultraviolet rays.Autodarkening: Helmets have been developed that have a battery-powered photoelectric cell built in.The lens is clear until an arc is struck.The circuitry of the photoelectric cell then instantly darkens the lens.*
Arc SafetyExcess ultraviolet rays may cause eye pain for 8 to 18 hours after exposure.Infrared and ultraviolet light rays can severely injure the eyes; every precaution should be taken to shield the eyes from these rays.*
ShieldA shield is used in a metal shop for jobs such as grinding and cutting.Similar design to a welding helmet.Headbands on the shield are adjustable.Made of fiber, plastic or fiberglass and is formed in a shape that covers the front half of the head.Can not be used to weld with.*
Safety GlassesA welder must wear safety glasses at all time under a welding helmet or shield. They enable the operator to set up work, chip welds and still have eye protection from flying particles.*
ClothingWhile an arc weld is in progress, the molten flux and the metal itself sometimes spatter for a considerable distance around the joint being welded.The operator must, therefore, be protected from the danger of being burned by these hot particles. Such clothing as gloves, cap, cape, shoes and aprons.All these clothing articles should be made of leather or approved clothing for welding.*
Welding GlovesWelding gloves are made of leather and are wore during welding. Gloves should be worn to cover the hands and wrists and to prevent sunburnDuring the welding process, skin not covered will be exposed to UV rays and sunburned.*
Welding CapA welding cap can be worn underneath the welding helmet. Protects top of head from spatter.Helpful when welding overhead.*
Welding CapeA welding cape is worn to protect shoulders and arms from spatter.
Welding BootsWelding boots should be made of leather and high topped. NO tennis shoes*
Welding PantsPants should be jean/coverall material.Pants worn by the welder should not have cuffs.Cuffs may catch burning particles as they fall.*
Welding ApronsA welding apron can be worn over a long sleeve shirt during welding to protect the front of the operator. *
*AWS Classification of SMAW Electrodes
SMAW ElectrodesElectrodes have a solid metal wire core and a thick flux covering (coating). These electrodes are identified by the wire diameter and by a series of letters and numbers. These letters and numbers identify the metal alloy and the intended use of the electrode.The common diameters are 1/16, 3/32, 1/8, 5/32, 3/16, 7/32, 1/4, 5/16, and 3/8.Available in lengths from 9 to 18. Most common is 14.The electrodes are usually purchased in 50 lb. packages*
SMAW ElectrodesSMAW electrodes are produced for welding on many metals and alloys including:Carbon SteelsLow-Alloy SteelsCorrosion-Resistant SteelsCast IronsAluminum and Aluminum alloysCopper and Copper AlloysNickel and Nickel AlloysSurfacingAlloy: Pure metal that has additional metal or nonmetal elements added while molten. The alloy has mechanical properties that are improved from the pure metal.*
SMAW ElectrodesFlux: The covering on a shielded metal arc welding electrodeThe flux on the electrode performs many different functions.1. Producing a protective gas around the weld area.2. Providing fluxing elements and deoxidizers.3. Creating a solid coating over the weld as it cools.4. Establishing electrical characteristics.5. Adding alloying elements.*
1. Protective GasDuring the arc process, some of the flux covering changes to neutral gases or reducing gases such as carbon monoxide (CO) or hydrogen (H).These gases prevent oxygen from coming in contact with the molten metal.
2.Fluxing ElementsThe covering also contains special fluxing ingredients that work to remove impurities from the molten metal.Impurities