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The tubular frame for the roadster shown is formed using mild steel - Leaving Cert Engineering - Question 5 - 2018
Question 5
The tubular frame for the roadster shown is formed using mild steel. (i) Describe, with the aid of a diagram(s), a suitable welding process to manufacture the mild ... show full transcript
Worked Solution & Example Answer:The tubular frame for the roadster shown is formed using mild steel - Leaving Cert Engineering - Question 5 - 2018
Step 1
Describe, with the aid of a diagram(s), a suitable welding process to manufacture the mild steel frame shown.
Answer
One suitable welding process for manufacturing the mild steel frame is Metal Inert Gas (MIG) welding. This method involves the use of a continuously fed wire electrode that melts to create a weld pool, protected by an inert gas like argon. The following aspects highlight the MIG welding process:
- Setup: MIG welding is relatively easy to set up and use. The welding torch can be maneuvered easily, allowing for precision work in tubelar frames.
- Operation: The wire electrode is fed continuously into the weld pool, generating the necessary heat for bonding the metal parts together.
- Advantages: It provides a cleaner weld when compared to other methods, as it does not produce slag. Furthermore, MIG welding is ideal for thinner materials known for their ease of use and speed.
Diagram of MIG welding setup can be included here.
Step 2
Outline three safety features integrated into the welding technique selected.
Answer
Three safety features integrated into the MIG welding process include:
- Protective Shields: The use of an inert gas shield prevents sparks and heat from damaging surrounding materials and protects the operator from exposure to harmful UV radiation.
- Ventilation: Welding booths are often ventilated to expel harmful fumes, thus ensuring that workers are not exposed to hazardous situations.
- Personal Protective Equipment (PPE): Welders are required to wear appropriate safety gear, including gloves, helmets, and protective clothing to guard against heat, sparks, and splatter.
Step 3
Describe how multi-run welding can positively affect the quality of a weld.
Answer
Multi-run welding promotes a superior quality weld by allowing for better control over heat input and penetration. Each successive pass can overlap slightly with the previous one, which helps to:
- Improve overall weld strength by ensuring even heat distribution.
- Fill any gaps or inconsistencies created during the initial pass, thus enhancing the overall solidity of the weld.
Step 4
Outline the principles of submerged arc welding.
Answer
In submerged arc welding, the welding process involves the following principles:
- A bare wire electrode is fed automatically through a hopper, generating heat through electric arc.
- The arc is submerged under a layer of granular flux that protects it from external contaminants.
- Additionally, this flux facilitates the formation of slag that protects the cooling weld pool, allowing for smoother and stronger welds.
Step 5
Give two benefits of the formation of slag in manual metal arc welding.
Answer
The formation of slag in manual metal arc welding offers various advantages:
- Protection: Slag acts as a barrier to protect the molten weld pool from atmospheric contamination, improving the integrity and quality of the weld.
- Cooling: It helps control the cooling rate of the weld, reducing the risk of cracking and brittleness in the finished product.
Step 6
Describe two safety hazards associated with resistance spot welding.
Answer
Resistance spot welding poses several safety hazards, including:
- Electric Shock: As high currents are passed through the workpieces, there is a substantial risk of electric shock to the operator due to improper handling or equipment failure.
- Fumes and Particles: The process generates heat and sparks, which may release harmful fumes. Proper ventilation and protective gear are essential to mitigate these risks.
Step 7
Outline three ways in which oxidation may be prevented during welding.
Answer
Oxidation can be effectively mitigated through the following methods during welding:
- Inert Gas Shielding: Using an inert gas like argon or nitrogen during the welding process creates a protective atmosphere around the weld, preventing oxidation.
- Flux Coating: Applying a flux coating before welding acts as a barrier against oxidizing agents in the air.
- Granulated Flux Usage: Using granulated flux that covers the weld area also helps to limit oxygen exposure during the welding process.
Step 8
Describe, with the aid of suitable diagrams, the three flame types associated with oxy-acetylene welding with reference to each of the following: - Constituents of each flame - Ratio of oxygen to acetylene gases in each flame - Temperature of each flame - Uses of each flame.
Answer
The three flame types associated with oxy-acetylene welding include:
-
Neutral Flame:
- Constituents: A balanced mix of oxygen and acetylene.
- Ratio: 1:1 ratio.
- Temperature: Approximately 3300°C.
- Uses: Best for welding steel and providing good quality welds.
Diagram can illustrate a neutral flame here.
-
Oxidizing Flame:
- Constituents: Excess oxygen in the mixture.
- Ratio: Greater than 1:1 ratio.
- Temperature: Up to 3500°C.
- Uses: Used for welding brass and can easily oxidize the metals if not monitored.
Diagram can illustrate an oxidizing flame here.
-
Carburizing Flame:
- Constituents: Excess acetylene.
- Ratio: Less than 1:1 ratio.
- Temperature: Approximately 3150°C.
- Uses: Preferred for welding aluminum and alloys where it provides a reducing atmosphere to prevent oxidation.
Diagram can illustrate a carburizing flame here.