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Two industrial welding processes are illustrated at A and B below - Leaving Cert Engineering - Question a - 2010
Question a
Two industrial welding processes are illustrated at A and B below. (i) Name the two welding processes; (ii) Identify one application for each process; (iii) Descr... show full transcript
Worked Solution & Example Answer:Two industrial welding processes are illustrated at A and B below - Leaving Cert Engineering - Question a - 2010
Step 1
Step 2
Identify one application for each process:
Answer
Applications for each process are as follows:
- MIG Welding: It is commonly used for welding light sheet metals in the automotive industry.
- TIG Welding: This process is often used for welding more specialized materials such as stainless steel in high precision applications.
Step 3
Describe the principles of operation for any one of these welding processes:
Answer
Principles of MIG Welding:
MIG (Metal Inert Gas) welding is a semi-automatic welding process where a consumable wire electrode is continuously fed into the weld pool. The key components include:
- Electrode Wire: It acts as the filler material that melts and fills the joint.
- Inert Gas: An inert gas, usually Argon, is used to shield the weld from contaminants in the atmosphere.
- Welding Torch: The operator guides the torch, which generates an electric arc between the wire electrode and the metal being welded.
The heat from the arc melts both the electrode and the base material, allowing them to fuse together as the molten metal solidifies.
Step 4
Answer any three of the following:
Answer
Safety features integrated into oxyacetylene equipment:
- Color-coded Cylinders: Gas cylinders are color-coded for safety (acetylene in maroon, oxygen in black).
- Regulator Safety Features: Regulators have distinct color coding, while acetylene has left-handed threads to prevent mixing.
- Flashback Arrestors: These are placed between hoses to prevent flames from traveling back into the cylinder.
- Adequate Ventilation Systems: Ensure proper airflow to prevent the accumulation of gas.
Functions of the slag produced in manual metal arc welding:
- Protective Coating: Slag forms a coating that protects the weld from oxidation.
- Slowing Cooling Rate: It helps in cooling the weld more slowly, preventing cracking and brittleness.
- Impurity Filtration: The slag captures impurities that may affect the final weld quality.
Identify one use of submerged arc welding (SAW):
Submerged Arc Welding (SAW) is commonly used for large scale welding tasks such as steel reinforcing beams, shipbuilding, and bridge construction.
Describe the principle of resistance welding:
Resistance welding involves placing the materials to be joined between two electrodes and applying pressure. An electric current is then passed through the materials, generating heat due to electrical resistance. This heat melts the materials at the joint, forming a strong bond once cooled. Spot welding is a common form of this technique, effective for metal sheets.
Step 5
Describe, with the aid of suitable diagrams, the main features of one of the following:
Answer
Electro-slag Welding:
Electro-slag welding is an automatic welding process used to join thicker plates. It involves placing the plates to be welded in a vertical position. Key features include:
- The gap between the plates can be quite large, allowing molten metal to well up and fuse the edges.
- Water-cooled copper shoes prevent excess molten metal from escaping.
- The electrode and flux create the molten slag that facilitates welding.
Oxyacetylene Welding:
Oxyacetylene welding is a fusion welding process where a flame is concentrated on the joint edges. Key features are:
- Regulator Setup: Regulators control the flow of both acetylene and oxygen from their respective cylinders.
- Flashback Arrestor: Prevents the flame from traveling back into the cylinders.
- Welding Torch: The torch mixes the gases and controls the flame size for optimal welding.
- Strengthening by filler material as needed for the joint.