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Welding Fusion 1 Definition Fusion welding is a group of processes that bond metal together by heating a portion of each piece above the melting point and causing them to flow together. Usually uses a filler material to insure the joint is filled. All fusion welding processes have three requirements. Heat Shielding Filler material 2 Fusion Welding Process Learning the basics 1. "Welding and cutting requires good eye-mindhand coordination." 1. Must be able to concentrate. 2. Must see and understand the activity in the molten metal as the process is occurring. 3. Thorough understanding of the operation of the equipment. 4. Must have good depth perception. 1. Must be able to determine the time and place to apply heat and/or filler metal. 2. Maintain a good body position so it is possible to look left and right, and ahead and behind the puddle. 3. Must know the quality standards. 4. Must understand the procedures for inspecting work. 5. Must learn safe work habits. 3 Fusion Welding--Heat Sufficient heat must be applied to the weld zone to raise the temperature above the melting point. Melting point is different for each material. Material Tin Lead Zinc Aluminum Silver Copper Cast Iron Melting Point (oF) 450 620 786 1,220 1,760 1,980 2,300 Material Steel (HC) Stainless Steel Steel (MC) Steel (LC) Iron Chromium Titanium Melting Point (oF) 2,500 2,550 2,600 2,700 2,800 3,000 3,260 4 Fusion Welding--Heat cont. The source of the heat is one of the primary differences between the welding processes. SMAW GMAW GTAW OFW Electric arc Electric arc Electric arc Gas Flame 5 Fusion Welding--Shielding Metals are produced in an environment devoid of atmospheric air. If atmospheric air is allowed to mix with the molten metal during the fusion welding process the quality of the weld is reduced. The method used for shielding is another difference in the common welding processes. SMAW GMAW GTAW OFW Inert gas from flux Inert gas from cylinder Inert gas from cylinder Gas Flame 6 Fusion Welding--Filler Material When a filler material is not provided during a fusion welding process the joint may be starved of metal. Starved joints have reduced strength. For this reason, joints are usually slightly over filled (reinforced) to insure the strength is not reduced. Reinforcement does not increase the strength of the weld, just insures the joint is not starved. Excessive reinforcement costs extra to produce and many times must be removed. 7 Fusion Welding--Filler Material cont. The source of the filler material is also one of the differences between the different welding processes. SMAW GMAW GTAW OFW Consumable electrode Welding wire Manual rod Manual rod 8 Fusion Welding's Five (5) Factors Which Determine The Quality Of The Weld Angle Heat Manipulation Distance Speed 9 Heat It is important to remember heat and temperature are not the same. The amount of heat (BTU's) required for a fusion weld is determined by the type of metal, metal thickness and welding position. Heat is measured in BTU's Temperature is measured in degrees Fahrenheit. Temperature is a measure of the intensity of the heat. In fusion welding processes, the amount of heat must be sufficient to raise the temperature of the metal above the melting point. 10 Controlling Welding Heat Six (6) ways of controlling welding heat 1. Equipment size 2. Equipment settings 3. Distance from heat source to work 4. The Manipulation of the heat source 5. Heat source angle 6. The travel speed 11 Distance The critical distance varies with each welding process. OFW--inner cone to work SMAW--electrode end to work GMAW--Contact to tube work GTAW--Cup to work Proper jointing and cutting will not occur if the distance is varied beyond the recommended limits. 12 Angle Two angles are important in welding. The best angle to use is different for each type of weld, welding position and welding process. 13 Speed The ideal travel speed is different for each weld, weld position and welding process. Operator must watch the welding process and adjust speed as needed. Speed indicators are: A. B. C. Size of bead Shape of ripples Penetration 14 Manipulation Some outcomes of improper Insure manipulation is necessary to produce manipulation the desired weld. 1. Reduced depth of fusion. Manipulation (movement) of the electrode, gun or torch is sometimes necessary to 2. Undercutting produce the desired results. 3. Porosity 1. Control puddle in vertical, horizontal 4. Slag inclusions and overhead welds. 5. Unnecessary wear on 2. Fill joint joins of fingers and 3. Desired appearance wrist. Two points to remember 1. 2. Make sure there is a sound reason for the manipulation. Select a manipulation pattern that will produce the desired results. 15 Types of Welds 16 Five Types of Welds Surface Groove Fillet Plug Slot 17 Surface Welds Surface welds are welds were material has been applied too and/or blended with the surface of the work piece. Two common applications are for hard surfacing and padding. Surface weld nomenclature A: Electrode wire B: Electrode flux C: Arc D: Weld puddle E: Bead F: Slag G: Gas shield 18 Groove Welds Groove welds are used to fuse the sides or ends of two pieces of metal. The primary use of groove welds is to complete butt joints. Groove weld nomenclature A: Toe B: Width C: Face reinforcement D: Toe E: Joint preparation F: Joint gap G: Root reinforcement H: Joint face I: Base metal 19 Fillet Welds Fillet welds have a triangular cross section and are used to fuse two faces of metal that are at a 90 degree angle to each other. Three common types are: T Lap Corner Fillet weld nomenclature A: Reinforcement B: Toe C: Face D: Throat E: Toe F: Leg G: Root H: Base metal I: Leg 20 Plug Welds Plug welds are used to attach two surfaces together when a complete joint is not required and the design does not allow for any weld bead outside the dimensions of the metal. The holes can be made with a drill bit. The weld is completed by establishing the arc on the bottom plate and then continuing to weld until the hole is full. 21 Slot Welds Slot welds are identical to plug welds except for the shape of the holes. For slot welds, slots are machined or stamped in the upper plate. They are completed the same as plug welds. 22 Five Types of Joints 23 Five Types of Joints Corner Butt Lap T Edge 24 Butt Joints Used to attach two metal face together. Joint preparation is dependent on the size of electrode and thickness of metal. No joint preparation is required if the electrode and power supply can supply sufficient heat for full penetration. Usually one or the other is a limiting factor. Three examples for 1/8 inch SMAW electrode: 25 Corner Joints Three common types: Closed Partially open Fully open 26 Lap Joints Lap joints are use to attach metal that overlaps. Three times metal thickness provides maximum strength. Multiple pass welds are used when electrode diameter or the power supply is a limiting factor. 27 Edge Joints Used to weld two surfaces at 180 degrees. Multiple pass is used when the electrode or power supply is the limiting factor. 28 Five Welding Positions Flat Horizontal Vertical up Vertical down Overhead 29 Questions 30

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