Welding Shop workshop for nust mech course

Welding Shop workshop for nust mech courseWelding Shop workshop for nust mech course

1. Welding ME-105 Workshop Practice College of E&ME, NUST Pakistan

2. Welding Welding is a fabrication process that joins materials by using heat to melt the parts together and allowing them to cool causing fusion. Welding is used for making permanent joints.

3. Weld Joints

4. Types of Welding

5. Arc Welding The welding in which electric arc is produce to give heat for the purpose of joining two surfaces is called electric arc welding. Electricity travels from electrode to base metal to ground.

6. Equipment A welding generator (D.C.) or Transformer (A.C.) Two cables- one for work and one for electrode Electrode holder Electrode Protective shield Gloves Wire brush Goggles

7. Arc Welding

8. Shielded Metal Arc Welding (SMAW) It is one of the most common welding process also known as stick welding. The electric current travels through the air gap between the end of the electrode wire and the base metal. As the electric current flows through this air gap, an electric arc is formed.

9. Shielded Metal Arc Welding (SMAW) Electrode used is this process is consumable, covered with flux. Electrode melts and become a part of the weld. The flux forms a protective layer for the weld. As the flux covering on the electrode wire melts, a shielding gas is created. When the flux cools, it solidifies and forms a protective slag over the weld bead.

10. SMAW - illustrated

11. Gas Metal Arc Welding (GMAW) GMAW employs a continuously feed electrode and shielding gas. Shielding gas should be inert. GMAW is also known as MIG (Metal Inert Gas). Unlike SMAW, this process is relatively faster since the electrode is fed continuously to the welding area along with inert gas GMAW is also referred to as Metal Inert Gas (MIG) Welding.

12. GMAW - illustrated

13. Advantages and Disadvantages of Arc Welding Advantages Most efficient way to join metals Lowest-cost joining method Affords lighter weight through better utilization of materials Joins all commercial metals Provides design flexibility Disadvantages Manually applied, therefore high labor cost. Need high energy causing danger Not convenient for disassembly. Defects are hard to detect at joints.

14. Oxy-acetylene Welding Acetylene when combined with oxygen burns at a temperature of 3000 °C to 3500 °C. As a fuel acetylene's primary disadvantage, in comparison to other fuels, is high cost.

15. Equipment Gas Cylinders Pressurized oxygen in one cylinder and acetylene in the other cylinder. Regulators Working pressure of oxygen 10psi Working pressure of acetylene 5psi Pressure Gauges Hoses Welding torch Check valve Non return valve

16. Oxy Acetylene Welding- illustrated

17. Grove and Fillet Welding Positions Normally, the following numbers and letters are used. For groove welding positions- 1G – (flat welding position) 2G – (horizontal welding position) 3G – (vertical welding position) 4G – (welding position overhead or overhead) 5G – (uphill/downhill vertical welding position) 6G/6GR – (overhead vertical welding position) For fillet welding positions- 1F – (flat welding position) 2F – (horizontal welding position) 3F – (vertical welding position) 4F – (welding position overhead or overhead)

18. Grove and Fillet Welding Positions

19. Lab Task: Welding a Tee Joint Tee welding joints are formed when two members intersect at a 90° angle which makes the edges come together in the center of a plate or component   Tee Joints are considered a type of fillet weld and can also be made when a pipe or tube is welded onto a base plate