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(a) (i) Describe the differences between any two of the following joining processes: Gas welding - Leaving Cert Engineering - Question 4 - 2008
Question 4
(a) (i) Describe the differences between any two of the following joining processes: Gas welding. Adhesive bonding. Arc welding. (ii) Suggest one suitable applic... show full transcript
Worked Solution & Example Answer:(a) (i) Describe the differences between any two of the following joining processes: Gas welding - Leaving Cert Engineering - Question 4 - 2008
Step 1
Describe the differences between any two of the following joining processes: Gas welding, Adhesive bonding
Answer
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Gas Welding:
- In gas welding, a flame produced by burning a gas (usually acetylene) in oxygen creates heat sufficient to melt the base materials and filler rod. This process ideally operates at extremely high temperatures (around 3200°C).
- It is commonly used for welding high gauge steel materials. The process allows both the base metals and filler material to fuse effectively, creating a strong joint.
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Adhesive Bonding:
- Adhesive bonding uses a chemical adhesive to join dissimilar materials. These adhesives can be in liquid or solid forms and work by creating a bond through chemical reactions or by mechanical interlocking at the surface of the materials.
- The technique is suitable for applications where heat may damage the substrates, such as in the assembly of electronic components. The bonds formed can vary widely in strength and resistance based on the formulation of the adhesive.
Step 2
Suggest one suitable application for each process selected at 4(a)(i)
Answer
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Gas Welding Application:
- Joining of light gauge steel pipes, which requires a robust and heat-sensitive process to ensure structural integrity without distortion.
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Adhesive Bonding Application:
- Car brake pads to steel shoes, where a strong, heat-resistant bond is needed without altering the properties of the components.
Step 3
Explain, with the aid of suitable diagrams, how the following oxy-acetylene flames are produced: (i) Neutral flame, (ii) Carburising flame, (iii) Oxidising flame.
Answer
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Neutral Flame:
- This flame is produced by mixing equal volumes of oxygen and acetylene. It is characterized by a well-defined inner cone and an outer envelope. It provides sufficient heat for most welding processes.
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Carburising Flame:
- This flame has more acetylene than oxygen, resulting in a longer inner cone. It is used for welding high carbon steels. The excess acetylene introduces carbon into the weld pool, which is beneficial when working with certain materials.
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Oxidising Flame:
- In this flame, oxygen is present in excess compared to acetylene. This flame type produces a shorter, sharper inner cone and is used for welding materials that require a clean weld, such as brass.
Step 4
Explain any three of the following in relation to soldering: (i) Tinning, (ii) Flux, (iii) Capillary action.
Answer
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Tinning:
- Tinning is the process of coating surfaces to be soldered with a thin layer of solder. This ensures better adhesion when joining the materials as it prevents oxidation and promotes a stronger bond.
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Flux:
- Flux is a substance applied to the surfaces to be soldered. It helps in removing oxidation and impurities, facilitating a solid bond by improving wetting action during the soldering process.
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Capillary Action:
- Capillary action helps solder to flow into tight joints by drawing the solder into the gap between the parts being joined. This phenomenon is critical for creating a strong joint, as the solder needs to fill the space effectively.
Step 5
Why is it essential to wear protective equipment when welding?
Answer
Wearing protective equipment while welding is crucial for several reasons:
- It protects against harmful UV radiation emitted during the welding process, which can cause serious skin burns and eye damage (such as arc eye).
- Protective gear shields the body from hot metal splashes and sparks that can cause burns.
- It ensures personal safety against inhalation of harmful fumes and particulates generated during welding, which could have long-term health effects.