INDEXING METHODS

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• Q1: Define Indexing.
  Ans: Indexing is the process of dividing a workpiece into equal parts by rotating it through a specific angle using a dividing head.
• Q2: Name the types of Indexing.
  Ans: Types of indexing are:

  • ➔ Direct (Rapid) Indexing
  • ➔ Plain (Simple) Indexing
  • ➔ Differential Indexing
  • ➔ Angular Indexing
• Q3: What is Direct or Rapid Indexing Method?
  Ans: Direct or rapid indexing is a method in which the workpiece is directly rotated using an index plate with fixed holes, without using worm gear mechanism.
• Q4: Write the formula for Rapid Indexing.
  Ans: Formula:
  
  Number of holes to move = Total holes / Number of divisions
• Q5: Write the formula for Index Plate#1.
  Ans: Index Plate #1 holes: 15, 16, 17, 18, 19, 20
  Formula:
  
  Movement = Hole Circle / Divisions
• Q6: Write the formula for Index Plate#2.
  Ans: Index Plate #2 holes: 21, 23, 27, 29, 31, 33
  Formula:
  
  Movement = Hole Circle / Divisions
• Q7: Write the formula for Index Plate#3.
  Ans: Index Plate #3 holes: 37, 39, 41, 43, 47, 49
  Formula:
  
  Movement = Hole Circle / Divisions
• Q8: Calculate the Indexing to mill hexagon on Milling machine by using Direct Indexing Method.
  Ans: For hexagon, number of sides = 6
  
  Step 1: Use 24 hole plate (standard)
  Step 2: Formula = Total holes / Divisions
  = 24 / 6 = 4 holes
  
  Answer: Move 4 holes for each division
• Q9: What is a Plain or Simple Indexing Method?
  Ans: Plain or simple indexing is a method in which the workpiece is rotated using a worm and worm gear mechanism with a standard ratio of 40:1.
• Q10: Write the formula for Plain Indexing.
  Ans: Formula:
  
  Indexing = ⁴⁰/_Z turns of crank
• Q11: Calculate indexing to cut spur gear of 17 teeth.
  Ans: Formula:
  
  Indexing = 40 / Z
  
  
  = 40 / 17
  
  This cannot be done by simple indexing directly because 17 is a prime number.
  So, Differential Indexing is required.
• Q12: Calculate indexing to cut spur gear of 48 teeth.
  Ans: Formula:
  
  Indexing = 40 / Z
  
  = 40 / 48 = 5 / 6 turn
  
  = 0.833 turn
  = 5 holes in 6 hole circle
  
  Answer: 5 holes on 6-hole circle
• Q13: Calculate indexing to cut spur gear of 60 teeth.
  Ans: Formula:
  
  Indexing = 40 / Z
  
  = 40 / 60 = 2 / 3 turn
  
  = 0.666 turn
  = 8 holes in 12 hole circle
  
  Answer: 8 holes on 12-hole circle
• Q14: Calculate indexing to cut spur gear of 80 teeth.
  Ans: Formula:
  
  Indexing = 40 / Z
  
  = 40 / 80 = 1 / 2 turn
  
  = 0.5 turn
  = 10 holes in 20 hole circle
  
  Answer: 10 holes on 20-hole circle
• Q15: Calculate indexing to cut spur gear of 100 teeth.
  Ans: Formula:
  
  Indexing = 40 / Z
  
  = 40 / 100 = 2 / 5 turn
  
  = 0.4 turn
  = 8 holes in 20 hole circle
  
  Answer: 8 holes on 20-hole circle
• Q16: What is a Differential Indexing Method?
  Ans: Differential indexing is a method used when the required divisions cannot be obtained by simple indexing. It uses a gear train to rotate the index plate slightly.
• Q17: Write the formula for Differential Indexing.
  Ans: Formula:
  
  Gear Ratio = (N - n) / n
  
  Where:
  N = nearest number
  n = required divisions
• Q18: What is an Angular Indexing Method?
  Ans: Angular indexing is a method in which the workpiece is rotated through a specific angle instead of equal divisions.
• Q19: Write the formula for Angular Indexing.
  Ans: Formula:
  
  Crank Movement = (^Angle/₃₆₀) × 40
• Q20: Calculate angular index for 30°- 30'-30''
  Ans: Given angle = 30° - 30' - 30''
  
  Step 1: Convert into decimal degree
  = 30 + (30/60) + (30/3600)
  = 30 + 0.5 + 0.0083
  = 30.5083°
  
  Step 2: Use formula
  Crank Movement = (Angle / 360) × 40
  
  = (30.5083 / 360) × 40
  = 3.39 turns
  
  Answer: 3.39 turns of crank
• Q21: Calculate differential index for 20°.
  Ans: Step 1: Convert angle into divisions
  Divisions (n) = 360 / 20 = 18
  
  Step 2: Choose nearest number (N)
  Let N = 20
  
  Step 3: Apply formula
  Gear Ratio = (N - n) / n
  = (20 - 18) / 18
  = 2 / 18 = 1 / 9
  
  Answer: Gear ratio = 1 / 9
• Q22: What is an Index Hole?
  Ans: Index hole is a hole on the index plate used to position the crank for accurate rotation.
• Q23: What is an Index Circle?
  Ans: Index circle is a set of holes arranged in a circular pattern on the index plate used for indexing operations.