451. As tool and work are not in contact in EDM process

1. 1. no relative motion occurs between them

   
   
   

   2. no wear of tool occurs

   
   
   

   3. no power is consumed during metal cutting

   
   
   

   4. no force between tool and work occurs

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   NA

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452. Estimate the MRR (in cc/sec) of an alloy containing 18% cobalt, 62% nickel and 20% chromium during ECM with current of 500 ampere. The density of the alloy is 8.28 g/cc. The following data is available.
     

     Metal	Gram atomic weight	Valency
     Cobalt	58.93	2
     Nickel	58.71	2
     Chromium	51.99	6

     
     Assume Faraday's constant is 96500 coulombs/ mole.

1. 1. 1.24 × 10^–3 CC/sec.

   
   
   

   2. 1.24 × 10^–2 CC/sec.

   
   
   

   3. 24 × 10^–2 CC/sec.

   
   
   

   4. 1.24 × 10^–4 CC/sec.

   
   
   

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1. View Hint View Answer Discuss in Forum

   Given data:
   Current (I) = 500 cump.
   Density (f) = 8.28 g/cc.
   

   MRR =	AI
   	ρZF

   
   where, A = atomic weight Z = Valency
   F = Faraday’ s constant= 96500
   

   	Z			=	Z1x1	+	Z2x2	+	Z3x3
   	A		equivalent		A1		A2		A3

   
   

   =	2 × 0.18	+	2 × 0.62	=	6 × 6 0.2	= 5.03 × 10–2
   	58.93		58.71		51.99

   
   

   MRR =	500
   	8.28 × 5.03 × 10–2 × 96500

   
   = 1.24 × 10^–2 CC/sec.

   Correct Option: B

   Given data:
   Current (I) = 500 cump.
   Density (f) = 8.28 g/cc.
   

   MRR =	AI
   	ρZF

   
   where, A = atomic weight Z = Valency
   F = Faraday’ s constant= 96500
   

   	Z			=	Z1x1	+	Z2x2	+	Z3x3
   	A		equivalent		A1		A2		A3

   
   

   =	2 × 0.18	+	2 × 0.62	=	6 × 6 0.2	= 5.03 × 10–2
   	58.93		58.71		51.99

   
   

   MRR =	500
   	8.28 × 5.03 × 10–2 × 96500

   
   = 1.24 × 10^–2 CC/sec.

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453. Machining of complex shapes on CNC machine requires

1. 1. simultaneous control of x, y and z axes

   
   
   

   2. simultaneous control of x and y axes

   
   
   

   3. independent control of x and y axes

   
   
   

   4. independent control of x, y and z axes

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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454. In finish machining of an island on a casting with CNC milling machine, an end mill with 10 mm diameter is employed, The corner points of the Island are represented by (0, 0), (0, 30), (60, 30) and (50, 0). By applying cutter radius compensation, the trajectory of the cutter will be

1. 1. (-5, 0), (-5, 35), (55, 35), (55, -5), (-5, 5)

   
   
   

   2. (0, -5), (55, -5). (55, 35), (-5, 35), (-5, -5)

   
   
   

   3. (5,5), (5, 25), (45,25),(45, 5), (5, 5)

   
   
   

   4. (5, 5), (45, 5), (45, 25), (5, 25), (5, 5)

   
   
   

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1. View Hint View Answer Discuss in Forum

   Given = Dia of end milling cutter = 10 mm
   

   Correct Option: B

   Given = Dia of end milling cutter = 10 mm
   

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455. In finish machining of an island on a casting with CNC milling machine, an end mill with 10 mm diameter is employed, The corner points of the Island are represented by (0, 0), (0, 30), (60, 30) and (50, 0). By applying cutter radius compensation, the trajectory of the cutter will be

1. 1. (-5, 0), (-5, 35), (55, 35), (55, -5), (-5, 5)

   
   
   

   2. (0, -5), (55, -5). (55, 35), (-5, 35), (-5, -5)

   
   
   

   3. (5,5), (5, 25), (45,25),(45, 5), (5, 5)

   
   
   

   4. (5, 5), (45, 5), (45, 25), (5, 25), (5, 5)

   
   
   

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1. View Hint View Answer Discuss in Forum

   Given = Dia of end milling cutter = 10 mm
   

   Correct Option: B

   Given = Dia of end milling cutter = 10 mm
   

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