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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 when conducting a filing test on a hard metal, it is essential to utilize proper filing techniques. This can be achieved by using the right type of file that matches the material and ensuring that the filing is done gently. Additionally, the following points should be considered:
- File on the tip or edge of the metal: This will minimize pressure on the file's surface.
- Apply chalk to the file surface: Chalk can help reduce friction, which in turn decreases wear on the file.
Step 2
What is the purpose of the heat treatment of steel?
Answer
The purpose of heat treatment of steel is to alter its properties and improve its performance characteristics. Specifically, heat treatment serves to:
- Change the properties/grain structure: This modification can enhance the strength, hardness, and toughness of the steel.
Step 3
Give TWO reasons for tempering hardened steel.
Answer
Tempering hardened steel is a crucial process, and there are several reasons for doing so:
- To reduce the brittleness caused by the hardening process: This helps in preventing the steel from cracking under stress.
- To increase the toughness of the steel: Tempering can improve the overall durability and performance of the hardened steel.
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.
- It is soaked at that temperature for a specified duration.
- Finally, the steel is cooled very slowly to encourage maximum softness.
3.4.2 Hardening
- The steel is heated slightly higher than the upper critical temperature (Ac3).
- It is soaked at that temperature for the required time.
- The steel is then rapidly cooled by quenching in rapid cooling medium.