521. Helix angle of fast helix drill is normally

1. 1. 35 deg

   
   
   

   2. 60 deg

   
   
   

   3. 90 deg

   
   
   

   4. 5 deg

   
   
   

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1. View Hint View Answer Discuss in Forum

   α = 35°

   Correct Option: A

   α = 35°

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522. Tool life of a 10 hours is obtained when cutting with a single point tool at 63 m/min. If Taylor's constant C = 257.35, tool life on doubling the velocity will be

1. 1. 5 hours

   
   
   

   2. 25.7 min

   
   
   

   3. 38.3 min

   
   
   

   4. unchanged

   
   
   

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1. View Hint View Answer Discuss in Forum

   V₁ =63m/min T₁ = 60 hours = 600 min
   C = 257.35
   V₁T₁ⁿ = C
   63 × (100)ⁿ = 257.35
   n = 0.22
   V₂T₂ⁿ = 257.35
   2 V₂T₂ⁿ = 257.35
   2 × 63 (T₂)0.22= 257.35
   T2 = 25.6min

   Correct Option: B

   V₁ =63m/min T₁ = 60 hours = 600 min
   C = 257.35
   V₁T₁ⁿ = C
   63 × (100)ⁿ = 257.35
   n = 0.22
   V₂T₂ⁿ = 257.35
   2 V₂T₂ⁿ = 257.35
   2 × 63 (T₂)0.22= 257.35
   T2 = 25.6min

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523. The rake angle in drill

1. 1. Increase from centre to periphery

   
   
   

   2. Decreases from centre to periphery

   
   
   

   3. Remains constant

   
   
   

   4. Is irrelevant to the drilling operation

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   NA

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524. Machine tool, structures are made... for high process capability (tough/rigid/strong)

1. 1. rigid

   
   
   

   2. tough

   
   
   

   3. strong

   
   
   

   4. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   Rigid

   Correct Option: A

   Rigid

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525. The effect of rake angle on the mean friction angle in machining can be explained by

1. 1. Sliding model of friction

   
   
   

   2. Sticking and then sliding friction model

   
   
   

   3. Sticking friction model

   
   
   

   4. Sliding and then sticking friction model

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: B

   NA

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