NATIONAL CERTIFICATE (VOCATIONAL) MATERIAL TECHNOLOGY NQF LEVEL 3 NOVEMBER 2009

Transcription

1 NTIONL ERTIFITE (VOTIONL) MTERIL TEHNOLOGY NQF LEVEL 3 NOVEMER 2009 ( ) 3 November (X-Paper) 09:00 12:00 This question paper consists of 7 pages.

2 ( ) -2- N1520(E)(N3)V TIME: 3 HOURS MRKS: 100 INSTRUTIONS N INFORMTION nswer LL the questions. Read LL the questions carefully. Number the answers according to the numbering system used in this question paper. LL sketches must be neat and in proportion. LL work you do not want to be marked, must be clearly crossed out. Write neatly and legibly.

3 ( ) -3- N1520(E)(N3)V QUESTION 1: GENERL 1.1 Indicate whether the following statements are TRUE or FLSE. hoose the answer and write only 'true' or 'false' next to the question number ( ) in the NSWER OOK Pig iron is crude iron cast in blocks called pigs. The most commonly known non-ferrous metals are copper and aluminium. sbestos is chemically inert and does not decay. Non-metals are not ductile. Tempering temperatures vary between 120 and 550. In hardness testing of materials the Rockwell scale uses a 1,8 mm diameter hardened steel ball as an indenter. 1.2 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 Which of the following non-ferrous metals are used for telegraph and telephone wires? Tin opper Zinc Lead Which ONE of the following are NOT thermoplastics? Nylon Urea crylics PV Which is the most suitable tempering colour for screwdrivers, saws for wood and springs? rown ark straw ark blue Pale straw

4 ( ) -4- N1520(E)(N3)V Which test method is carried out to ensure that a metal has enough ductility? Torsional strength test method Tensile test method ending test method rinell hardness test method What test is also used to establish whether or not a particular heat treatment has been correctly carried out? Impact test ompressive test Shear test Tensile test What is a yield point? Reduction of area The stress at which deformation changes Maximum tensile force Given load 1.3 omplete the following sentences by filling in the missing word(s). Write only the word(s) next to the question number ( ) in the NSWER OOK Non-metals are brittle and therefore not. The best known non-metal is. The cupola furnace is made from steel plate and lined with. The rotor furnace is one method used for the manufacturing of. The key principle of the essemer converter is that it removes from the iron by oxidation. When a plain carbon steel is heated in a furnace, its rises constantly until it reaches a certain point. Steels with carbon content below cannot be hardened. shear test is mainly used for thin in metals or composites.

5 ( ) -5- N1520(E)(N3)V QUESTION 2: METLS Name the THREE groups into which carbon steels are usually grouped. Name FOUR uses of medium carbon steel that have a carbon content of 0,3 to 0,5 carbon. efine malleability. Name TWO properties of lead. Explain ONE use of aluminium in industry. Name ONE use of antimony in industry. Give the effect of tungsten on steel. iscuss the reasons why high speed steels are used in industry. iscuss why magnesium alloys are so useful in the industry. QUESTION 3: NON-METLS Name FIVE uses of asbestos. iscuss THREE properties of carbon. Explain the characteristics of polyurethane. Name the THREE major groups of phosphorus. iscuss the applications of selenium. (5) (5)

6 ( ) -6- N1520(E)(N3)V QUESTION 4: METL PROESSING 4.1 escribe the working principles of an arc furnace. 4.2 Name the type of converter in FIGURE 1 and label the numbered parts FIGURE 1 (6) 4.3 Name TWO advantages of tempering. 4.4 Explain: The carburising process The case hardening process 4.5 iscuss the advantages of the cupola furnace.

7 ( ) -7- N1520(E)(N3)V QUESTION In FIGURE 2 below differently shaped anvils that are used with the Rockwell hardness tester are shown. Name the parts numbered Explain the torsional properties that materials must have in order to conduct a torsion test. 5.3 In FIGURE 3 below different types of rupture that may occur in a torsion test are shown. Name the types numbered escribe the method used in a tensile test. (5) efine tensile strength. Show the formula that can be used to obtain the tensile strength. TOTL: 100