11. Calculate the bite angle when rolling plates 12 mm thick using work rolls 600 mm diameter and reducing the thickness by 3 mm

1. 1. 1.73°

   
   
   

   2. 4.71°

   
   
   

   3. 4.73°

   
   
   

   4. 5.73°

   
   
   

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   D = 600 mm , R =	D	= 300 mm
   	2

   
   h_i = 12 mm
   ∆h = 3 mm
   

   θ = tan-1		√R∆h
   		{ R - (∆h / 2) }

   
   

   θ = tan-1		√300 × 3
   		{ 300 - (3/ 2) }

   
   θ = 5.73°

   Correct Option: D

   D = 600 mm , R =	D	= 300 mm
   	2

   
   h_i = 12 mm
   ∆h = 3 mm
   

   θ = tan-1		√R∆h
   		{ R - (∆h / 2) }

   
   

   θ = tan-1		√300 × 3
   		{ 300 - (3/ 2) }

   
   θ = 5.73°

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12. A cylindrical riser of 6 cm diameter and 6 cm height has to be designed for a sand casting mould for producing a steel rectangular plate casting of 7 cm × 10 cm × 2 cm dimensions having the total solidification time of 1.36 minute. The total solidification time (in minute) of the riser is _____.

1. 1. 4.133 min

   
   
   

   2. 7.133 min

   
   
   

   3. 3 min

   
   
   

   4. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   	V			=		7 × 10 × 2		= 0.673 cm
   	A		casting			2(7 × 10 + 7 × 2 + 2 × 10)

   
   

   	V			=		(π / 4)d3
   	A		Top riser			{ (π / 4)d2 + πd2 }

   
   

   	V			=	d	=	6	= 1.25
   	A		Top riser		S		5

   
   

   	V			=		(π / 4)d3		=	d	= 1 cm
   	A		Bottom riser			{ (π / 2)d2 + πd2 }			6

   
   

   tTop riser		=	(V / A)2Top riser	=		1.2		2
   tcasting			(V / A)2casting			0.673

   
   t_{Top riser} = 4.133 min
   

   tBottom riser		=	(V / A)2Bottom riser	=		1		2
   tcasting			(V / A)2casting			0.673

   
   t_{Bottom riser} = 3 min
   

   Correct Option: B

   	V			=		7 × 10 × 2		= 0.673 cm
   	A		casting			2(7 × 10 + 7 × 2 + 2 × 10)

   
   

   	V			=		(π / 4)d3
   	A		Top riser			{ (π / 4)d2 + πd2 }

   
   

   	V			=	d	=	6	= 1.25
   	A		Top riser		S		5

   
   

   	V			=		(π / 4)d3		=	d	= 1 cm
   	A		Bottom riser			{ (π / 2)d2 + πd2 }			6

   
   

   tTop riser		=	(V / A)2Top riser	=		1.2		2
   tcasting			(V / A)2casting			0.673

   
   t_{Top riser} = 4.133 min
   

   tBottom riser		=	(V / A)2Bottom riser	=		1		2
   tcasting			(V / A)2casting			0.673

   
   t_{Bottom riser} = 3 min
   

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13. Light impurities in the molten metal are prevented from reaching the mould cavity by providing

1. 1. Strainer

   
   
   

   2. Bottom well
      

   
   
   

   3. Skim bob
      

   
   
   

   4. All of the above

   
   
   

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   (c) Skin bob
   

   Correct Option: C

   (c) Skin bob
   

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14. A 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
    

1. 1. 48.32 mm
      

   
   
   

   2. 49.90 mm
      

   
   
   

   3. 49.94 mm
      

   
   
   

   4. 49.96 mm

   
   
   

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   Side after

   Correct Option: A

   Side after

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15. In a gating system, the ratio 1 : 2 : 4 represents
    

1. 1. sprue base area : runner area : ingate area
      

   
   
   

   2. pouring basin area : ingate area : runner area
      

   
   
   

   3. sprue base area : ingate area : casting area
      

   
   
   

   4. runner area : ingate area : casting area

   
   
   

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1. View Hint View Answer Discuss in Forum

   
   

   Correct Option: B

   
   

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