661. Consider the following statements: During the third stage of tool wear, rapid deterioration of tool edge takes place because
     1. Flank wear is only marginal
     2. Flank wear is large
     3. Temperature of the tool increases gradually
     4. Temperature of the tool increases drastically
     Which of the statements given above are correct?
     

1. 1. 1 and 3
      

   
   
   

   2. 2 and 4
      

   
   
   

   3. 1 and 4
      

   
   
   

   4. 2 and 3

   
   
   

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   Correct Option: B

   

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662. In a machining operation chip thickness ratio is 0.3 and the back rake angle of the tool is 10°. What is the value of the shear strain?
     

1. 1. 0.31
      

   
   
   

   2. 0.13
      

   
   
   

   3. 3.00
      

   
   
   

   4. 3.34
      

   
   
   

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   r = 0.3 =	t1	, α = 10°
   	t2

   
   

   tanφ =	rcosα
   	1 - rsinα

   
   

   tanφ =	0.3cos10°
   	1 - 0.3sin10°

   
   φ = 17.3°
   Shear strain = tan (φ – α) + cot φ
   Shear strain = tan (17.3 – 10) + cot 17.3
   Shear strain = 3.34

   Correct Option: D

   r = 0.3 =	t1	, α = 10°
   	t2

   
   

   tanφ =	rcosα
   	1 - rsinα

   
   

   tanφ =	0.3cos10°
   	1 - 0.3sin10°

   
   φ = 17.3°
   Shear strain = tan (φ – α) + cot φ
   Shear strain = tan (17.3 – 10) + cot 17.3
   Shear strain = 3.34

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663. A job of the shape shown in the figure below is to be machined on a lathe. The tool best suited for machining of this job must have
     
     

1. 1. positive side rake angle
      

   
   
   

   2. positive back rake angle
      

   
   
   

   3. positive cutting edge inclination angle
      

   
   
   

   4. negative cutting edge inclination angle

   
   
   

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   Should be cut by negative SCEA.

   Correct Option: A

   Should be cut by negative SCEA.

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664. Orthogonal machining of a steel workpiece is done with a HSS tool of zero rake angle. The ratio of the cutting force and the thrust force on the tool is 1 : 0.372. The length of cut chip is 4.71 mm while the uncut chip length is 10 mm. What is the shear plane angle φ and friction angle β in degree?
     Use Merchants theory
     

1. 1. 32.49, 10.22
      

   
   
   

   2. 25.22, 20.41
      

   
   
   

   3. 64.78 20.41
      

   
   
   

   4. 25.22, 23.21

   
   
   

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   α = 0 ,	Fc	=	1	, Lc = 4.71 , Luc = 10 mm
   	FT		0.372

   
   

   	LC	=	t1	=	4.71	= r
   	LUC		t2		10

   
   r = 0.471 chip reduction coefficient
   

   tanβ =	FT	, where α = 0
   	FC

   
   β = tan^–1(0.372) = 2071°
   

   tanφ =	rcosα
   	1 - rsinα

   
   

   tanφ =	0.471cos0
   	1 - 0.471sin0

   Correct Option: B

   α = 0 ,	Fc	=	1	, Lc = 4.71 , Luc = 10 mm
   	FT		0.372

   
   

   	LC	=	t1	=	4.71	= r
   	LUC		t2		10

   
   r = 0.471 chip reduction coefficient
   

   tanβ =	FT	, where α = 0
   	FC

   
   β = tan^–1(0.372) = 2071°
   

   tanφ =	rcosα
   	1 - rsinα

   
   

   tanφ =	0.471cos0
   	1 - 0.471sin0

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665. A single point cutting tool with a nose radius of 0.4 mm was used to turn a component in a lathe employing feed rate of 0.3 mm/rev. If the feed rate is doubled, the ideal surface roughness (peak-to-valley height) produced on the components will increase by a factor of
     

1. 1. 2
      

   
   
   

   2. 4
      

   
   
   

   3. 8
      

   
   
   

   4. 16

   
   
   

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   Hmax1 =	f2
   	8R

   
   

   Hmax2 =	2f2	= 4Hmax1
   	8R

   Correct Option: B

   Hmax1 =	f2
   	8R

   
   

   Hmax2 =	2f2	= 4Hmax1
   	8R

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