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Tap Drill Chart
Metric Tap Drill Chart
Tap Speed Chart
Table 302 303

 

FACTORS THAT DETERMINE TAPPING SPEED
Appropriate tapping speeds are determined by the following factors: Material to be tapped, hole depth (through or blind), depth of thread, thread pitch, percentage of thread, lubrication, machine equipment, and whether tapping is to be horizontal or vertical.

DETERMINING SPEEDS
Speeds, tap drill sizes and thread percentages can be calculated using tables below.

Speeds my be INCREASED under the following conditions: When using a spiral point, when percentage of thread decreases, when quality and quantity of coolant improves, and when thread pitch gets finer.

Speed MUST be DECREASED under the following conditions: When thread depth increases, when using bottom taps, when using coarser thread taps, when running tapered (by 1/4 to 1/2), when using pipe taps, and when quality and quantity of coolant is restricted.

TAPPING SPEED GUIDE
FACTORS TO BE CONSIDERED WHEN DETERMINING TAPPING SPEED:
  • Material to be Tapped
  • Hole Depth (through or blind)
  • Depth of Thread
  • Thread Pitch
  • Percentage of Thread
  • Lubrication
  • Machine Equipment
  • Horizontal or Vertical Tapping
SPEEDS MAY BE INCREASED:
  • When using a Spiral Point
  • As the Percentage of Thread Decreases
  • As the Quality and Quantity of Coolant Lubricant Improves
  • As You go to Finer Pitch Threads
SPEEDS MUST BE DECREASED:
  • When Thread Depth Increases
  • When Using Bottom Taps
  • When Using Coarser Thread Taps
  • By 1/4 to 1/2 When Running Tapered Pipe Taps
  • When The Quality and Quantity of Coolant or Lubricant is Restricted
RPM
=
     SFM     
.26 X TAP O.D.
 
To use this formula for Metric, convertMetric to Inch Equivalent by multiplyingMetric sizes times .03937

 

         

MATERIAL SPEED FEET
PER MINUTE
 
Aluminum Alloys 90-100
Brass 60-100
Bronze 40-60
Cast Iron:  
Ductile, Annealed 60
Ductile, as Cast 30
Ductile, Tempered 15-20
Gray, Annealed 80
Gray, as Cast 35-60
Malleable 60
Malleable, Heat Treated 25-50
Copper 40-60
Magnesium Alloys, Annealed 175
Monel, Annealed 20
Nickel Alloys, Annealed 25
Plastics:  
Thermo 50
Thermosetting 50
Steel:  
Carbon (Low) 40-60
Carbon (High) 25-35
Cast 20-45
Chromium 10-45
Cobalt 10-45
Free Cutting 50-80
Hardened 10-25
Leaded 45-60
Manganese 10-35
Molybdenum 10-35
Nickel 10-35
Tool 10-25
Vanadium 10-35
Stainless Steel 10-35
Prec. Hardening 10-25
Sintered Metal 50-70
High Temperature Alloys:  
Titanium 10-40
Inconel 5-15
Hastalloy 5-15
Rene 41 5-15
Waspaloy 5-15
Zinc Die Cast 100-150