NATIONAL CERTIFICATE (VOCATIONAL) FITTING AND TURNING NQF LEVEL 2 SUPPLEMENTARY EXAMINATION 2010

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Hugh Atkins
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1 NTIONL ERTIFITE (VOTIONL) FITTING ND TURNING NQF LEVEL 2 SUPPLEMENTRY EXMINTION 2010 ( ) 4 March (X-Paper) 09:00 12:00 This question paper consists of 7 pages and a 1-page formula sheet. opyright reserved

2 ( ) -2- N1050(E)(M4)V TIME: 3 HOURS MRKS: 100 INSTRUTIONS ND INFORMTION nswer LL the questions. Read LL the questions carefully. Number the answers according to the numbering system used in this question paper. LL work you do not want to be marked, must be clearly crossed out. Write neatly and legibly. opyright reserved

3 ( ) -3- N1050(E)(M4)V QUESTION 1: GENERL Various options are given as possible answers to the following questions. hoose the answer and write only the letter ( ) next to the question number ( ) in the NSWER OOK. 1.1 What marking off medium does not work if there is any grease or oil on the surface? Gentian violet mixture opper sulphate halk 1.2 When turning between centres on a lathe, the work-piece is supported by a chuck on the one side and a on the other side. tailstock. mandrel. steady. 1.3 Which of the following machines will give a very smooth finish? Surface grinder Milling machine Drilling machine 1.4 What tool is used to break away the slag on a weld? Wire brush File hipping hammer 1.5 What milling machine would you use to machine a keyway on a shaft? Drill bit Slot drill Plain helical cutter 1.6 The diameter of an HSS cutter with a speed of 25 m/min set to run at 300 r/min will be 26,52 mm. 50,41 mm. 45,36 mm. 1.7 What is the level of accuracy that can be measured by a micrometer? 0,10 mm 0,01 mm 0,05 mm opyright reserved

4 ( ) -4- N1050(E)(M4)V 1.8 The speed change on the sensitive drilling machine is regulated by rack and pinion. v-pulleys. gearbox. 1.9 ONE unsafe condition in the welding workshop is sufficient ventilation. good housekeeping. faulty welding equipment ONE disadvantage of a three-jaw chuck is correct any run out. do facing and boring. easily mount the workpiece. (10 1) [10] QUESTION 2: MRKING OFF 2.1 Why must a template be securely held in position when doing marking off? (2) 2.2 Explain the purpose of checking work that is completed. 2.3 Name an instrument that you would use to check if the inside diameter of the part is the same as the drawing or the template. 2.4 There are groups of measuring instruments used in the workshop. hoose any TWO of them and give ONE example for each. (4) [8] QUESTION 3: DRILLING MHINE 3.1 The FIGURE below shows an example of a clamping device. Give the name of the device and explain its purpose. opyright reserved (2)

5 ( ) -5- N1050(E)(M4)V 3.2 Explain, with the aid of sketches, the difference between a finger clamp and a -clamp. (4) 3.3 The cutting speed for bronze is 30 m/min. alculate the speed in revolutions per second of the machine spindle for the drilling of a hole with a diameter of 12 mm. (4) 3.4 hole size is given as ,05 What is the upper limit and the lower limit of the hole? (2) 3.5 Measuring equipment is required when working on a drilling machine in order to identify faulty work and compare the dimensions to the information on the technical drawing. Which instrument would you use to check the Roundness of a hole Size of a hole 3.6 Give TWO reasons that can cause early failure of twist drills. (2) 3.7 Name any TWO types of equipment that need to be cleaned and oiled after use on the drilling machine. (2) [18] QUESTION 4: MILLING MHINE 4.1 What is the purpose of the dividing head on the milling machine? 4.2 The milling machine is a machine which cuts metals by using a variety of cutting tools called milling cutters. How would you use the following milling cutters during a milling operation: (4) Dovetail cutter Slotting cutter End mill cutter Slot drill cutter 4.3 Name THREE different malfunctions on the milling machine that could lead to problems when performing a job. (3) 4.4 alculate the feed rate in millimetres/minute that would be required when using an end mill to machine a brass workpiece with a 25 mm diameter HSS end mill. The cutting speed for brass is 45 m/min and the feed per tooth is 0,18. The number of teeth is 4. (5) 4.5 alculate the required indexing, using a incinnati dividing head as shown on the FORMUL SHEET (below) to cut a gear with 23 teeth. (5) [18] opyright reserved

6 ( ) -6- N1050(E)(M4)V QUESTION 5: SURFE GRINDER 5.1 Differentiate between horizontal spindle reciprocating table and horizontal spindle rotary table. (2) 5.2 Explain how you would rectify the following surface grinding faults: Scratching of work urning of work hatter marks 5.3 What is meant by the following grinding wheel terms? Grade Structure 5.4 Name THREE malfunctions on the surface grinding that could lead to problems when performing a job. (3) [10] QUESTION 6: ENTRE LTHE 6.1 workpiece with a diameter of 100 mm must be machined on a lathe turning at a speed of 180 r/min. Determine the cutting time in minutes if one rough cut is taken over a length of 500 mm. The feed rate is 0,2 mm per revolution of the workpiece. (6) 6.2 When preparing for the workpiece to be machined on the lathe, the tools and equipment must be checked for their effectiveness. Name any FOUR features that you would look at when checking the lathe and its condition. (4) 6.3 The cutting speed for bronze is given as 25 m/min. alculate the rotational speed in r/min, when turning a bar with a diameter of 60 mm. The spindle speeds available are 40, 65, 95, 125 and 169 r/min. Which speed would you recommend? (4) 6.4 hoose the correct answer between the brackets in the following statement. The feed rate will be (slower/faster) for a soft material like aluminium and (slower/faster) for a hard material like mild steel. (2) 6.5 When working on a lathe machine you realise that the machine makes a strange noise. What could be the cause and how would you rectify this? (2) [18] opyright reserved

7 ( ) -7- N1050(E)(M4)V QUESTION 7: WELDING/JOINTS 7.1 Describe briefly how you will rectify the following welding defects: Undercut Poor fusion (2) (2) 7.2 s a welder you are required to report problems, changes or malfunctions of the welding process. Describe how you would solve the following welding problems: rc is unstable No shielding gas No feeding of electrode Electrode wire bends 7.3 Name FOUR types of welders' clothing. (4) 7.4 List any FIVE unsafe conditions in the welding workshop. (5) 7.5 Explain why an extension cable should always be fully extended and not rolled up. [18] TOTL: 100 opyright reserved

8 ( ) -8- N1050(E)(M4)V FORMUL SHEET 1. Indexing = 40 N 2. Indexing = N 9 3. F = ft x T x N 4. S = πdn 5. Time(min) = number of cuts Feed rate 6. Time(sec) = time(min) x 60 opyright reserved

NATIONAL CERTIFICATE (VOCATIONAL) FITTING AND TURNING NQF LEVEL 4 NOVEMBER 2009

NATIONAL CERTIFICATE (VOCATIONAL) FITTING AND TURNING NQF LEVEL 4 NOVEMBER 2009 NTIONL ERTIFITE (VOTIONL) FITTING N TURNING NQF LEVEL 4 NOVEMER 2009 (6011044) 12 November (Y-Paper) 13:00 16:00 This question paper consists of 12 pages. opyright reserved (6011044) -2- N1070(E)(N12)V