lesson 8 applying tungsten inert gas (tig) welding techniques

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  • Slide 1
  • Lesson 8 Applying Tungsten Inert Gas (TIG) Welding Techniques
  • Slide 2
  • Next Generation Science/Common Core Standards Addressed! Words and phrases as they are used in a specific scientific or technical context relevant to grades 910 texts and topics. CCSS.ELA Literacy.RST.9 10.3Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or performing technical tasks, attending to special cases or exceptions defined in the text. CCSS.ELA CCSS.ELA Literacy. RST.11Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or performing technical tasks; analyze the specific results based on ex CCSS.ELA Literacy. RST.11 12.4 explanations in the text 12.3 Determine the meaning of symbols, key terms, anCCSS.ELA Literacy.RST.9 10.3Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or performing technical tasks, attending to special cases or exceptions defined in the text. CCSS.ELA Literacy.RST.9 10.4 Determine the meaning of symbols, key terms, and other domain specific words and phrases as they are used in a specific scientific or technical context relevant to grades 910 texts and topics. CCSS.ELA Literacy. RST.11Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or performing technical tasks; analyze the specific results based on ex CCSS.ELA Literacy. RST.11 12.4 explanations in the text 12.3 Determine the meaning of symbols, key terms, and other domain specific words and phrases as they are used in a specific scientific or technical context relevant to grades 1112 texts and topics. MP.4 Model with mathematics. (HS PS1 4 d other domain specific words and phrases as they are used in a specific scientific or technical context relevant to grades 1112 texts and topics. MP.4 Model with mathematics. (HS PS1 4
  • Slide 3
  • Student Learning Objectives 1. Explain the advantages and developments of the Tungsten Inert Gas (TIG) welding process. 2. Describe applications for the Tungsten Inert Gas (TIG) welding process. 3. Explain how the Tungsten Inert Gas (TIG) welding process works. 4. Identify the types of shielding gases used for TIG welding.
  • Slide 4
  • Terms Centerless ground electrode Clean finished electrode Duty cycle Flowmeter Polarity Postweld purge time
  • Slide 5
  • Interest Approach Notice that these welds have been welded with fuel-gas, arc, MIG, and TIG welding. Can you tell what welding type was done on each? Compare and contrast each of them. What are the advantages and disadvantages of each process?
  • Slide 6
  • What are the advantages of using the Tungsten Inert Gas (TIG) welding process? What advancements have led to the development of the TIG welding process?
  • Slide 7
  • The Tungsten Inert Gas (TIG) welding process fuses metals by heating them between a non- consumable tungsten electrode and the base metal, while a continuous envelope of inert gas flows out around the tungsten electrode.
  • Slide 8
  • A. At one time, the American Welding Society called the process tungsten inert gas welding. The letters TIG were used to designate the process. 1. Later, the definition was changed to gas tungsten arc welding and the letters GTAW came into popular use. 2. Today, both of the letters and names are used.
  • Slide 9
  • B. The TIG process has several advantages that account for its popularity and increased use in the agricultural and welding industries. 1. Welds made with a gas-shielded arc are more corrosion resistant, more ductile, and stronger because the gas is able to completely exclude atmospheric air from the welding zone. Welds are not weakened by slag inclusion in the bead because the flux used is a gas.
  • Slide 10
  • The TIG Process 2. The TIG welding process is known for its consistency in producing high quality welds. 3. The welding process is easier than other methods because the weldor can clearly see the welding zone. There is a minimal amount of smoke, fumes, and sparks created by the TIG process.
  • Slide 11
  • The TIG Process 4. The finished weld requires little, if any, grinding or preparation before it can be painted. 5. There is usually less distortion of the workpiece because of the small heat affected zone.
  • Slide 12
  • The TIG Process 6. The TIG process has many applications because it can be used to make high quality welds in almost any metals and alloys. 7. Welds can be made with the TIG process either by applying filler rod to the puddle or by fusing the base metal without a filler rod.
  • Slide 13
  • The TIG Process 8. TIG can be performed by both automatic and manual techniques. 9. TIG may be done in all positions. 10. TIG may be used on a wide range of metal thickness.
  • Slide 14
  • What are the applications for the Tungsten Inert Gas (TIG) process?
  • Slide 15
  • With the technological developments made in TIG equipment, it is now the most versatile of all the fusion welding processes.
  • Slide 16
  • TIG Application A. The TIG process can be used to join most metals. It welds aluminum and magnesium and their alloys, alloy steels, carbon steels, stainless steels, copper, nickel and nickel alloys, titanium, tin, silicon, aluminum bronzes, and cast iron.
  • Slide 17
  • TIG Application B. The TIG process can be adapted for welding in the horizontal, vertical, and overhead positions as well as the flat position. 1. It is used extensively in applications where weld quality is critical, such as stainless steel piping systems. Stainless steel is used extensively in the dairy and food processing industries.
  • Slide 18
  • TIG Application 2. One limitation of the TIG welding process is the low deposition rate of the filler and metal. The TIG process will deposit less filler metal per pass than of the other processes. Because of the increased time needed to complete welds on thick metal, the TIG process is used most often on thinner metals.
  • Slide 19
  • How does the Tungsten Inert Gas (TIG) process work?
  • Slide 20
  • In the TIG process, an arc is struck between the non- consumable tungsten electrode and the work piece.
  • Slide 21
  • A. The thickness of the metal and the type of current being used determine the size of the tungsten electrode. B. The possible currents available are Direct Current Straight Polarity (DCSP), Alternating Current (AC), or Direct Current Reverse Polarity (DCRP).
  • Slide 22
  • C. The arc is covered by a layer of shielding gas which acts as the flux and keeps the nitrogen and oxygen in the air from coming in contact with the molten puddle. When the puddle is formed on the base metal, the torch is moved along the joint until the workpiece is fused together. 1. A filler rod may or may not be used.
  • Slide 23
  • C2. If a filler rod is used, it should be the same composition as the base metal. The filler rod is fed manually into the leading edge of the puddle. 3. The torch may be moved in a semicircular motion to vary the width of the bead.
  • Slide 24
  • D. The movement of the TIG torch and applying filler rod is similar to the movement used in braze welding with an oxy- fuel gas torch.
  • Slide 25
  • What are the types of Tungsten Inert Gas (TIG) equipment and accessories and what is their function?
  • Slide 26
  • The equipment used for TIG is somewhat different from that used in stick welding and much different from that used in MIG welding.
  • Slide 27
  • TIG Equipment A. A weldor should know that with certain accessories a regular AC, DC, or AC/DC welding machine can be fitted for TIG welding. 1. The heat energy put into the metal being welded is dependent upon the amperage, arc voltage, and polarity of the arc. The term polarity is used in describing DC welding circuits and refers to the direction of current flow.
  • Slide 28
  • TIG Equipment 2. Direct current flowing from the electrode () to the workpiece (+) is direct current straight polarity, or DCSP.
  • Slide 29
  • TIG Equipment 3. Current which flows from the workpiece () to the electrode (+) is direct current reverse polarity, or DCRP.
  • Slide 30
  • TIG Equipment B. Most TIG welding is done with AC or DCSP current. 1. When welding with AC, the machine will be either balanced or unbalanced. 2. With AC machines, the current, in theory, flows in DCSP half of the time and DCRP half of the time.
  • Slide 31
  • TIG Equipment 3. When the current flows in the DCRP half of the cycle, the current is flowing from the workpiece to the electrode, causing a high resistance to current flow. This resistance makes the tungsten electrode heat up. The resistance occurs because the current is flowing from a large conductor, the base metal, to a concentrated point in the tungsten electrode.
  • Slide 32
  • TIG Equipment 4. When in the DCSP half of the cycle, the current is flowing from the electrode tip, a small conductor, to the workpiece, a large conductor. This direction of current flow has a cooling effect on the tungsten and enhances its current-carrying capacity.
  • Slide 33

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