4.1 The picture below shows a MIG welding torch - NSC Agricultural Technology - Question 4 - 2020 - Paper 1

The function of A, the gas shroud, is to protect the contact tip from contamination by providing a shielding gas that prevents atmospheric gases from coming into contact with the molten weld pool, thus improving the quality of the weld.

Part B is typically manufactured from steel, often referred to as ferrous metals due to its iron content.

Small metal balls, known as spatter, can occur due to several reasons: if the shielding gas is not flowing correctly, if the plate being welded is dirty, or if the wrong type of electrode or settings are used. Additionally, improper distance from the weld joint can contribute to this issue.

To successfully perform a vertical butt-weld joint, the farmer should: 1. Ensure the two metal pieces are properly aligned and tack weld them together at the edges. 2. Use special electrodes to facilitate vertical welding. 3. Start the welding at the bottom and progress upwards at an angle of approximately 30 degrees to allow the molten metal to flow properly without running downward.

Two common types of welding runs that can be used are the zigzag pattern and the U-shape pattern, which ensure good penetration and spread of the weld.

The volume of the hole can be calculated using the formula: Volume of hole = length x breadth x height. Given that the volume of the hole equals 300 mm x 300 mm x 600 mm, we get:

Thus, the volume of the hole minus the pole is:

The volume of concrete to be ordered can be calculated from the volume of the hole minus the volume occupied by the pole, which was previously calculated as 49,300,000 mm³. For each of the four corner posts, the contractor would require:

The type of shrinking that occurs at arrow A is lateral shrinking, which happens due to the heat from the welding process.

To control distortion, one could employ methods such as pre-setting the metal before welding or by using welding of patch works to mitigate the stresses introduced by the heat.

Gauge A typically indicates the working/gas pressure at the outlet, while Gauge B indicates the gas volume/pressure inside the cylinder.

The oxyacetylene cutting process begins by lighting the torch to heat the material. Oxygen is introduced, and when the steel ignites, the operator maintains the cut by regulating the pressure to ensure a continuous flame to melt the steel effectively.

An operator would be cutting mild steel, as this metal interacts well with the oxygen in the cutting process to generate a clean cut.

The cause of the plasma cutter losing its arc can be due to a damaged contact tip or moisture in the system. This can be resolved by replacing the contact tip or installing a water trap to eliminate moisture.

The standard plasma-cutting electrodes are typically made from tungsten or copper.