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Cutting Formula

NC Spot Drill
Calculate spindle speed and feed rate:
1. Using your “d” value and cutting speed Vc from the data sheet, calculate spindle speed “S”(RPM).
2. “ F” feed rate per minute F = f x S = RPM x IPR
Metric Formula
Vc Cutting Speed m/min.  
d diameter mm  
S Spindle speed r.p.m (Vc x 1000)/(π x d)
f Feed rate per tooth mm/rev.  
F Feed rate per minute mm/min. Sxf

Inch Formula
SFM Surface Speed
(Vc (m/min.) x 3.28)
ft./min.  
d diameter inch  
S Spindle speed r.p.m (3.82xSFM)/d
f IPR inch/rev.  
F Feed rate per minute inch/min. Sxf

Calculation of NC Spot Drill
1. From Spot diameter “d” to get drill depth “ t ”.
2. Point angle “α” is determined by which tool holder you use.
3. From “d” draw a horizontal line to get intersection of the line by point angle “α”.
4. From the intersection draw a vertical line to the bottom to have depth of spotting “ t ”. “ t ” is the drill depth of
the NC program.
5. The sectional view of spotting will depend on the shape of insert, NC40 and other grades of inserts have
different sectional view.
6. For chamfering, do not use tip of insert, 1mm(0.04”) minimum clearance is required for a smooth surface finish.

N9MT-CT >> Insert Multi-function

Determine spindle speed and feed rate:
• Choose spotting depth to decide spotting diameter according to the Diameter/Depth chart.
• The spindle speed should be calculated by the maximum diameter of spotting, chamfering and grooving.

  Spotting Work Material Vc (m/min) f (mm/rev.) Grade of Insert 
spotting        Carbon Steel 150~250 0.05~0.10 NC40, NC2071
   Alloy steel 100~200 0.04~0.08 NC40, NC2071
   Stainless Steel 65~125 0.03~0.06 NC10, NC60, NC40, NC2071
   Cast iron 80-150 0.05~0.10 NC40, NC10, NC2071
  Non-Ferrous Metal (Al, Cu) 150~300 0.05~0.10 NC10, NC9076, NC2071
  Ti, Ti-alloy 40~80 0.03~0.08 NC9076
  Hardened steel HRC 40°~56° 30~60 0.03~0.08 NC60
* For technical construction reasons, the insert is not located on the center of the holder.
* Inserts with supporting edges can increase feed rate 50%.


  Chamfering Work Material Vc (m/min) f (mm/rev.) Grade of Insert 
chamfering        Carbon Steel 150~320 0.15~0.24 NC40, NC2071
   Alloy steel 100~250 0.12~0.20 NC40, NC2071
   Stainless Steel 65~125 0.10~0.20 NC10, NC60, NC40, NC2071
   Cast iron 150-250 0.15~0.25 NC40, NC10, NC2071
  Non-Ferrous Metal (Al, Cu) 150~320 0.15~0.25 NC10, NC9076, NC2071
  Ti, Ti-alloy 40~80 0.03~0.08 NC9076
  Hardened steel HRC 40°~56° 30~60 0.03~0.08 NC60


Grooving Work Material Vc (m/min) f (mm/rev.) Grade of Insert 
chamfering        Carbon Steel 150~250 0.05~0.10 NC40, NC2071
   Alloy steel 100~200 0.04~0.08 NC40, NC2071
   Stainless Steel 65~125 0.03~0.06 NC10, NC60, NC40, NC2071
   Cast iron 80-150 0.05~0.08 NC40, NC10, NC2071
  Non-Ferrous Metal (Al, Cu) 150~320 0.05~0.08 NC10, NC9076, NC2071
  Ti, Ti-alloy 40~80 0.03~0.08 NC9076
  Hardened steel HRC 40°~56° 30~60 0.03~0.08 NC60


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