Engineering - Exam Papers - OL - Paper - 1992
200 Marks
Answer Question 1, Sections A and B and THREE other questions.
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1.
(65 Marks)
Section A - 30 Marks
Give brief answers to any six of the following :
| (a) | State two safety precautions related to the use of a plastic strip heater. | |
| (b) | Give a common electrical example of | |
| (i) | a conductor, | |
| (ii) | an insulator, and | |
| (iii) | a semiconductor. | |
| (c) | What is bauxite? | |
| (d) | Name two types of electrical switch. | |
| (e) | Identify the two metals which compose brass. | |
| (f) | What is the purpose of matrix boards in electronics? | |
| (g) | State two safeguards for an electric hand drill. | |
| (h) | What is tinplate? | |
Section B - 35 Marks
Answer any three of the following :
| (i) | Describe the function and operation of a worm and wheel mechanism. |
| (j) | Explain any two of the computing terms: mouse, hard disk, serial port, screen resolution. |
| (k) | Explain the function of an electrical transformer. |
| (l) | Explain any two of the terms : light dependent resistor (LDR), vernier callipers, bimetallic strip, diode, bevel gear. |
| (m) | Name the mechanism shown in the diagram and explain how it functions. |
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2.
(45 Marks)
| (a) | State the main product of any three of the following: | |
| (i) | Electric arc process; | |
| (ii) | Basic oxygen process; | |
| (iii) | Electrolytic process; | |
| (iv) | Open hearth process. | |
| Describe any one of these processes. | ||
| (b) | Identify two properties of | |
| (i) | copper and | |
| (ii) | cast iron. | |
| (c) | Give a suitable application for each of the following: | |
| (i) | silver steel; | |
| (ii) | high speed steel; | |
| (iii) | stainless steel; | |
| (iv) | mild steel. | |
3.
(45 Marks)
| (a) | What is the purpose of annealing? In what circumstance is it used for heat treating metals generally? | |
| (b) | Explain the basis on which carbon steel is classified as: | |
| (i) | low carbon; | |
| (ii) | medium carbon; | |
| (iii) | high carbon. | |
| How does the annealing process differ for each of these cases? | ||
| (c) | A rod of 1% carbon steel, 10mm in diameter and 300mm long, is found to be slightly bent after hardening. Describe how the rod can be | |
| (i) | softened, | |
| (ii) | straightened and | |
| (iii) | rehardened without bending. | |
4.
(45 Marks)
| (a) | State whether a | |
| (i) | neutral, | |
| (ii) | carburising or | |
| (iii) | oxidising flame results from excess acetylene. | |
| Describe the flame and indicate one of the following as the appropriate flame temperature: 500°C or 1200°C or 3000°C |
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| (b) | Answer each of the following with regard to the use of oxy-acetylene welding equipment: | |
| (i) | state three relevant safety precautions; | |
| (ii) | Explain the essential difference between brazing and braze welding; | |
| (iii) | The welding technique shown in the diagram is: leftward welding or rightward welding or vertical welding. |
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| (c) | State the functions of the flux coating on an arc welding electrode. | |
OR |
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| (c) | Explain the purpose of any three of the following: | |
| (i) | pneumatic flow regulator; | |
| (ii) | robot arm; | |
| (iii) | stepper motor; | |
| (iv) | electronic sensor. | |
5.
(45 Marks)
| (a) | Identify | |
| (i) | two thermoplastics and | |
| (ii) | two thermosetting plastics. | |
| Give a typical application for each material. | ||
| (b) | Describe any two of the following terms related to plastics: | |
| (i) | strip heating; | |
| (ii) | dip coating; | |
| (iii) | laminating. | |
| (c) | A system for the manufacture of plastic products is shown in the diagram: | |
| (i) | Name the parts A, B, C, D and E. | |
| (ii) | Name the process. | |
| (iii) | Describe the operation of the system. | |
| (iv) | Identify any household product of the system. | |
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6.
(45 Marks)
| (a) | Discuss the advantages and disadvantages of 3 jaw and 4 jaw chucks with regard to: | |
| (i) | accuracy; | |
| (ii) | work holding; | |
| (iii) | operator skills. | |
| (b) | Explain the function of any three of the following: | |
| (i) | leadscrew; | |
| (ii) | rack and pinion; | |
| (iii) | quill;Using suitable diagrams, describe gauges for checking the size of (i) holes and (ii) shafts. | |
| (iv) | mandrel. | |
| (c) | Explain why it is necessary to have a range of spindle speeds available on a drilling machine. | |
OR |
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| (c) | What are the main advantages of operating a lathe by computer numerical control (CNC) rather than manual control? | |
7.
(45 Marks)
| (a) | Define the following terms, referring to a hole and shaft assembly: | |
| (i) | tolerance; | |
| (ii) | maximum clearance; | |
| (iii) | minimum clearance. | |
| (b) | Using suitable diagrams, describe gauges for checking the size of | |
| (i) | holes and | |
| (ii) | shafts. | |
| (c) | What reading is shown on the 25-30 mm micrometer represented in the diagram? Identify two other precision measuring tools used in engineering. |
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OR |
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| (c) | Give an example of the use of electronics in precision measurement. Explain any two of the following terms:- |
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| (i) | transistor; | |
| (ii) | relay; | |
| (iii) | integrated circuit (IC); | |
| (iv) | light emitting diode (LED). | |