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3.1 Explain how you will prevent damage to a file when conducting a filing test on a hard metal - NSC Mechanical Technology Fitting and Machining - Question 3 - 2019 - Paper 1
Question 3
3.1 Explain how you will prevent damage to a file when conducting a filing test on a hard metal. 3.2 What is the purpose of the heat treatment of steel? 3.3 Give T... show full transcript
Worked Solution & Example Answer:3.1 Explain how you will prevent damage to a file when conducting a filing test on a hard metal - NSC Mechanical Technology Fitting and Machining - Question 3 - 2019 - Paper 1
Step 1
Explain how you will prevent damage to a file when conducting a filing test on a hard metal.
Answer
To prevent damage to a file during a filing test on hard metal, it is essential to use proper filing techniques. This includes:
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Using the Right Filing Skills: Ensure that you employ the appropriate technique for filing, which helps maintain the integrity of the file.
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Filing on the Tip or Edge: Focus on using the tip or edge of the file rather than the flat surface. This minimizes contact with the material and reduces wear on the file.
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Applying Chalk to the File Surface: This technique reduces friction and helps to keep the file cutting efficiently, ultimately preventing overheating and damage.
Step 2
What is the purpose of the heat treatment of steel?
Answer
The heat treatment of steel serves primarily to alter its properties and grain structure. This process is crucial for enhancing its performance in various applications. Specifically, heat treatment aims to:
- Change the properties of steel to meet specific requirements, ensuring optimal performance.
- Modify the grain structure of steel, affecting its strength, toughness, and hardness.
Step 3
Give TWO reasons for tempering hardened steel.
Answer
Tempering hardened steel is an essential process that helps to improve its mechanical properties. The reasons for this process include:
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Reducing Brittle Fracture: Tempering reduces the brittleness developed during the hardening process, making the steel less prone to cracking under stress.
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Increasing Toughness: It relieves internal stresses, thus increasing the toughness of the steel, ensuring it can withstand impact and mechanical loads without failing.
Step 4
Describe how the following heat treatment processes are carried out on steel:
Answer
3.4.1 Annealing:
- The steel is heated to the prescribed temperature, allowing it to reach a uniform temperature throughout.
- It is then soaked at that temperature for a specified duration, ensuring thorough heat treatment.
- Finally, the steel is cooled very slowly, typically in the furnace, to minimize hardness and maximize softness.
3.4.2 Hardening:
- The steel is heated slightly higher than the upper critical temperature (Ac3).
- After reaching this temperature, the steel is soaked at it for a determined period.
- The steel is rapidly cooled by quenching in a fast-cooling medium, which enhances its hardness.