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sand casting by sk mondal

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Metal CastingBy S K Mondal1IES-2001The main purpose of chaplets is(a)To ensure directional solidification(b)To provide efficient venting(c)For aligning the mold boxes(d)To support the coresAns. (d)

Ans. (d) 2IES-1996Which of the following methods are used for obtaining directional solidification for riser design1.Suitable placement of chills2.Suitable placement of chaplets3.Employing paddingSelect the correct answer. Ans. (b)(a) 1 and 2 (b) 1 and 3 (c) 2 and 3 (d) 1, 2 and 3

Ans. (b)3IES 2007Which one of the following is the correct statement?Gate is provided in moulds to(a)Feed the casting at a constant rate(b)Give passage to gases(c)Compensate for shrinkage(d)Avoid cavitiesAAns. (a) correct reason: feed the casting at a controlled rate.4GATE-2009Match the items in Column I and Column II. Column I Column II P. Metallic Chills 1. Support for the core Q. Metallic Chaplets 2. Reservoir of the molten metal R. Riser 3. Control cooling of critical sections S. Exothermic Padding 4. Progressive solidification D(a)P-1,Q-3, R-2, S-4(b)P-1,Q-4, R-2, S-3(c)P-3, Q-4, R-2, S-1(d)P-4, Q-1, R-2, S-3

Ans. (d)5GATE-1992In a green-sand moulding process, uniform ramming leads to(a)Less chance of gas porosity(b)Uniform flow of molten metal into the mould cavity(c)Greater dimensional stability of the casting(d)Less sand expansion type of casting defect C

Ans. (c)

6GATE 2011Green sand mould indicates that(a) polymeric mould has been cured(b) mould has been totally dried(c) mould is green in colour(d) mould contains moisture D

Ans. (d) Green sand mould indicates that mould is not baked or dried. i.e., it contains moisture7IES-1995Which one of the following materials will require the largest size of riser for the same size of casting?(a)Aluminium (b)Cast iron (c)Steel (d)Copper. C

Ans. (c)8GATE-1999Which of the following materials requires the largest shrinkage allowance, while making a pattern for casting?(a)Aluminium (b) Brass (c) Cast Iron (d) Plain Carbon Steel D

Ans. (d) 9IES-1999In solidification of metal during casting, compensation for solid contraction is(a)Provided by the oversize pattern (b)Achieved by properly placed risers(c)Obtained by promoting directional solidification (d)Made by providing chills AAns. (a)10ISRO-2007Shrinkage allowance is made by(a) Adding to external and internal dimensions(b) Subtracting from external and internal dimensions(c) Subtracting from external dimensions and adding to internal dimensions(d) Adding to external dimensions and subtracting from internal dimensions A

Ans. (a) students make common mistake in this question and think answer will be (d). Take one example: How the iron ring is to place in the outer surface of the wheel of bullock cart? When metal temperature reduces its internal dimension also reduces and it make tight fit with wheel. In our case after casting when metal comes from solidus temperature to room temperature it will reduce its internal and external dimension therefore to compensate this we have to add in internal dimension also. 11GATE-2001Shrinkage allowance on pattern is provided to compensate for shrinkage when(a)The temperature of liquid metal drops from pouring to freezing temperature (b)The metal changes from liquid to solid state at freezing temperature(c)The temperature of solid phase drops from freezing to room temperature(d)The temperature of metal drops from pouring to room temperature C

Ans. (c)12GATE-2004Gray cast iron blocks 200 x 100 x 10 mm are to be cast in sand moulds. Shrinkage allowance for pattern making is 1%. The ratio of the volume of pattern to that of the casting will be(a) 0.97 (b) 0.99 (c) 1.01 (d) 1.03

D

Ans. (d)

Volume of pattern = (200+1%)x(100+1%)x(10+1%) = 202 x 101x 10.1 = 206060 mm3

Ratio of the volume of pattern to that of casting = 206060/200000 =1.0313GATE-2008While cooling, a cubical casting of side 40 mm undergoes 3%, 4% and 5% volume shrinkage during the liquid state, phase transition and solid state, respectively. The volume of metal compensated from the riser is(a) 2%(b) 7%(c) 8%(d) 9% B

Ans. (b) For riser we dont consider the shrinkage for solid state. For solid shrinkage pattern allowance will take care. 14GATE 2011A cubic casting of 50 mm side undergoes volumetric solidification shrinkage and volumetric solid contraction of 4% and 6% respectively. No riser is used. Assume uniform cooling in all directions. The side of the cube after solidification and contraction is(a) 48.32 mm(b) 49.90 mm(c) 49.94 mm(d) 49.96 mm AAns. (a) Volume of cube after solidification and contraction

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IAS-1995Assertion (A): A pattern is made exactly similar to the part to be cast.Reason (R): Pattern is used to make the mould cavity for pouring in molten for casting.(a)Both A and R are individually true and R is the correct explanation of A(b)Both A and R are individually true but R is not the correct explanation of A (c)A is true but R is false(d)A is false but R is true D

Ans. (d) It is not similar because fine details are removed and allowances are added.16IAS-2003Match List I (Material to be cast) with List II (Shrinkage Allowance in mm/m) and select the correct answer using the codes given below the lists: List-IList-II(Material to Cast) (Shrinkage Allowance in mm/m)(A)Grey cast iron1.7 - 10(B)Brass2.15(C)Steel3.20(D)Zinc4.24 ACodes:ABCDABCD(a) 12 34(b) 3 4 12(c) 1 4 32(d) 3 214Ans. (a) Shrinkage allowanceCast Iron10 mm/mBrass, Copper, Aluminium15 mm/mSteel20 mm/mZinc, Lead25 mm/m

17IES-1994Which of the following materials can be used for making patterns?1. Aluminium 2. Wax 3. Mercury4. LeadSelect the correct answer using the codes given below:Codes: D(a) 1,3 and 4 (b) 2,3 and 4 (c) 1, 2 and 4 (d) 1, 2 and 3

Ans. (d) 18GATE-2000Disposable patterns are made of(a)Wood (b)Rubber (c)Metal (d)Polystyrene D

Ans. (d)19IES-2008The pattern adopted for those castings where there are some portions which are structurally weak and are likely to break by the force of ramming are called: (a)Loose piece pattern(b)Follow board pattern (c)Skelton pattern (d)Single piece pattern B

Ans. (b) 20GATE 2012 (PI)In sand casting, fluidity of the molten metal increases with(A) increase in degree of superheat(B) decrease in pouring rate(C) increase in thermal conductivity of the mould(D) increase in sand grain size A

Ans. (a)21ISRO-2011Fluidity in casting (CI) operation is greatly influenced bya) Melting temperature of molten metal b) Pouring temperature of molten metalc) Finish of the mould d) Carbon content of molten metal B

Ans. (b)22IES 2007What is permeability? Permeability is more important in the basic process of sand casting than porosity. Give one important reason for this feature.[2 marks]IES-2002Assertion (A): In CO2 casting process, the mould or core attains maximum strength.Reason (R): The optimum gassing time of CO2 through the mould or core forms Silica Gel which imparts sufficient strength to the mould or core.(a)Both A and R are individually true and R is the correct explanation of A(b)Both A and R are individually true but R is not the correct explanation of A (c)A is true but R is false(d)A is false but R is true A

Ans. (a)24GATE 2008 (PI)In sand casting of a hollow part of lead, a cylindrical core of diameter 120 mm and height 180 mm is placed inside the mould cavity. The densities of core material and lead are 1600 kg/m3 and 11,300 kg/m3 respectively. The net force (in N) that tends to lift the core during pouring of molten metal will be(a) 19.7(b) 64.5(c) 193.7(d) 257.6 CAns. (c)

It is simply Buoyancy force25

IES-2008Small amount of carbonaceous material sprinkled on the inner surface of mould cavity is called(a)Backing sand (b)Facing sand (c)Green sand (d)Dry sand B

Ans. (b)26IES-2002In the grain -size determination using standard charts, the relation between the given size number n and the average number of grains 'N' per square inch at a magnification of 100 X is(a)N = 2n (b)N = 2n-lB (c)N = 2n + 1 (d)N = 2n + 1 Ans. (b)27IES 2011In light metal casting, runner should be so designed that:1. It avoids aspiration2. It avoids turbulence3. The path of runner is reduced in area so that unequal volume of flow through each gate takes place(a) 1 and 2 only(b) 1 and 3 only(c) 2 and 3 only(d) 1, 2 and 3 CAns. (c)28GATE 2010 (PI)During the filling process of a given sand mould cavity by molten metal through a horizontal runner of circular cross-section the frictional head loss of the molten metal in the runner will increase with the(a) increase in runner diameter(b) decrease in internal surface roughness of runner(c) decrease in length of runner (d) increase in average velocity of molten metal DAns. (d) Laminar flow therefore proportional to average velocity.

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IES 2011Match List I with List II and select the correct answer using the code given below the lists :

Codes AA B C D A B C D(a) 3 4 2 1(b) 1 4 2 3(c) 3 2 4 1(d) 1 2 4 3

List I List IIA. Top gate1. Heavy and large castingsB. Bottom gate2. Most widely used and economicalC. Parting gate3. TurbulenceD. Step gate4. Unfavourable temperature gradientAns. (a)30IES-1998A sand casting mould assembly is shown in the above figure. The elements marked A and B are respectively (a) Sprue and riser (b) Ingate and riser (c) Drag and runner (d) Riser and runner

A

Ans. (a) 31GATE-2002 The primary purpose of a sprue in a castingmould is to(a)Feed the casting at a rate consistent with the rate of solidification(b)Act as a reser