2 What is Welding?The process of joining two or more pieces of similar metals, through the application of heat and sometimes filler material.Base MetalPart 1Base MetalPart 2The two pieces have been joined using a Butt Joint
3 Overview of the WeldPenetrationThe most important aspect of any weld is the amount of penetration or the depth that the filler material fuses into the original workpiece or parent metal.
4 Welding can be broken down into two sub-categories. 1. Fusion2. Non-FusionAny welding operation involving melting of the base or parent metal.The joining of metals without melting the base or parent metal.Each sub-category can be broken into methods of weldingGas Welding (oxy-acetylene torch)GMAW (Gas Metal Arc Welding)SMAW (Shielded Metal Arc Welding)GTAW (Gas Tungsten Arc Welding)Brazing (oxy-acetylene torch)
5 Fusion Welding # 1 Gas Welding Oxygen Regulator GaugesAcetylene Regulator GaugesUses the heat created by a flame fueled by compressed acetylene gas and accelerated by compressed oxygenThe flame is created and maintained at the end of the torch tip and varied by controlling the line pressures as well as the valves for each compressed gasThree main flame types known as:Carburizing – too much acetylene in the mixtureNeutral – correct mixture of acetylene and oxygen to be used for weldingOxidizing – too much oxygen in the mixture, sometimes required for cuttingAcetylene TankOxygen TankShade 5 GogglesTorchFriction Lighter
6 Fusion Welding # 2 GMAW (MIG Welding) Gas Metal Arc WeldingMetal Inert Gas WeldingUses an electric arc to create heat for the welding processUses an automatically fed filler rod to help join the pieces of metal togetherUses shielding gas to prevent contaminants from entering the weld
7 The circuit must be completed to create an arc. Main UnitHose for Shielding GasGunGround ClampThe circuit must be completed to create an arc.
8 The parts of a MIG gun and the weld itself 184.108.40.206.5.6.7.Direction of travelContact Tip (Copper)Wire Filler RodShielding Gas / FumesWeld PoolSolidified WeldParent or Base Metal
9 Fusion Welding # 3 SMAW (Arc Welding) Shielded Metal Arc WeldingUses an electric arc to create the heat for the welding processUses a consumable electrode that provides the filler material for the weldElectrode can be coated to provide a shielding gas when burning off during the welding process
10 The circuit must be completed to create an arc. Main UnitElectrode HolderGround clampThe circuit must be completed to create an arc.
11 Arc Welding Electrodes vary in size, type, positional use and strength Arc Welding Electrodes vary in size, type, positional use and strength. The following example shows the meaning of the identifiers on a common electrodePower source (AC, DC or both), type of coating (low hydrogen, mineral, organic or rutile), type of arc (soft, medium or digging), penetration (light, medium or deep) and amount of iron powder in the coating.EElectrodePosition1 – All2 – Horizontal4 - VerticalTensile strength of weld in thousands of pounds per square inch
12 Fusion Welding # 4 GTAW (TIG Welding) Gas Tungsten Arc WeldingTungsten Inert Gas WeldingUses an electric arc to create the heat required for the welding processUses a torch with a tungsten electrode to produce the heat for the weld – torch also emits the shielding gas for the weldFiller rod is fed in by hand which makes it a very controlled weldWelding temperatures can be varied at any point during the weld via the foot pedal control
13 The circuit must be completed to create the arc.
14 Non-Fusion Welding # 1 Brazing Brazing is a method of joining metals together without fasteners or by using a fusion welding processA filler rod (usually bronze) is heated by an oxy-acetylene torch and melts at a lower temperature than the materials being joined, therefore allowing it to flow onto the materialWhen the bronze cools, it dries and forms a surface bond that is quite strongComparable to hot glue on wood products
15 Welding Safety Overview Proper eye protection must be worn at all timesShade 10 for all Arc welding processesShade 5 for brazing or gas weldingWelding curtains should always surround you to protect the other people working in your immediate areaSkin protection should also be worn including:Welding GlovesWelding Apron or Welding Coat
16 Prestart Checks Dampness or water in welding area Leaks in gas tanks (check with soapy water)Cable and hose condition (free of cracks, tears)Flammable or combustible materials in areaProper ventilation (is system turned on)