Describe the welding process shown below under the following headings: (i) Name; (ii) Method of operation; (iii) Applications - Leaving Cert Engineering - Question a - 2008

In TIG welding, an arc is established between a non-consumable tungsten electrode and the workpiece. An inert gas, typically Argon, is used to shield the weld area from atmospheric contamination. A filler metal may be added manually if needed to fill the joint. The TIG process allows for a high degree of control over the heat input, making it ideal for thin materials.

TIG welding is commonly used in high-quality welding applications where precision is paramount. It is suitable for various materials, including stainless steel and aluminum, and is often applied in industries such as aerospace, automotive, and fabrication.

• Color Coding: Oxygen cylinders are color-coded green and acetylene cylinders are red. This prevents misuse and helps distinguish between the two gases.
• Flashback Arrestors: These are installed to prevent flames from traveling back into hoses and equipment, which could lead to explosions.

Part A of the oxy-acetylene equipment consists of pressure regulators that control the flow and pressure of gases provided to the torch. Part B contains the gas mixing valve, which ensures the correct proportions of oxygen and acetylene are delivered to produce the desired flame.

Dissolved acetylene refers to acetylene gas that has been absorbed in acetone and stored in high-pressure cylinders. This method is used to safely store acetylene, as it is highly unstable when compressed alone.

• Oxidising Flame: Contains excess oxygen and has a temperature of up to 3500°C. It is used mainly for welding materials such as copper and brass, giving a sharp, pointed flame appearance.
• Carburising Flame: Contains excess acetylene, with a temperature of about 3150°C. It is used for welding aluminum and provides protection against oxidation, characterized by a feather-like appearance of the flame.

In resistance spot welding, two copper electrodes are used to join the components by pressing them together. An electric current passes through the electrodes, generating a large amount of heat at the interface. The heat causes the metal to melt and form a nugget, creating a strong, localized joint.

Metal Inert Gas (MIG) welding is a semi-automatic process that uses a continuous wire feed as the electrode. A shielding gas, such as Argon, is used to protect the molten weld pool from oxidation. The operator controls the feed rate of the wire and the gas flow, enabling efficient welding of thick materials without producing slag.