chemistry

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Calculating Cutting Speeds and Feed Rates for
CNC Computer Integrated Manufacturing
Unit 2 CNC Machining
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In this lesson

• Discuss different Cutting Tools.
• Calculate Cutting Speeds and Feed Rates.
• Practice.
• Download reference materials to share with your
  students.

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Basic Cutting Tools
Non- Center Cutting End Mill
Ball End Mill
Center Cutting End Mill
Indexable Shell Mill
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Obtain Reference Charts
Click here to open Cutting Speed Chart.
Click here to open Tool Feed Chart.
Click here to open Drilling Feed Chart.
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Calculating Spindle Speeds
Cutting Speed Obtained From Machinist Handbook
Tool Diameter
Revolutions per Minutes
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Recommended Cutting Speeds
Milling Speeds for High Speed Steel Tools Milling Speeds for High Speed Steel Tools
Material Cutting Speed in surface ft/min.
Magnesium 300
Aluminum 250
Brass and Bronze 150
Copper 100
Cast Iron (Soft) 80
Cast Iron (Hard) 50
Mild Steel 90
Cast Steel 80
Alloy Steel (Hard) 40
Tool Steel 50
Stainless Steel 60
Titanium 50
High Manganese Steel 30
Note Double Speed for Carbide Cutting Tools Note Double Speed for Carbide Cutting Tools
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Example
What spindle speed should be used to Mill
Aluminum with a ½ inch End Mill?
Cutting Speed for Aluminum is 250 surface ft./min.
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Example
What spindle speed should be used to Mill
Aluminum with a ½ inch End Mill?
Cutting Speed for Aluminum is 250 surface ft./min.
2000
RPM
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Your turn, ex. Spindle Speed
What spindle speed should be used to mill Soft
Cast Iron with a ¼ in. End Mill?
Cutting Speed for Soft Cast Iron is 80 surface
ft./min.
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Calculating Feed Rates
Fm ft x nt x N
Fm Feed Rate in inches/min.
ft Feed in inches / tooth
nt number of teeth on the tool
N Spindle Speed
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Recommended Tool Feed
Tool Feed (in/tooth) Tool Feed (in/tooth) Tool Feed (in/tooth)
Material Face Mill Side Mill End Mill
Magnesium .005-.020 .004-.010 .005-.010
Aluminum .005-.020 .004-.010 .005-.010
Brass and Bronze .004-.020 .004-.010 .005-.010
Copper .004-.010 .004-.007 .004-.008
Cast Iron (Soft) .004-.016 .004-.009 .004-.008
Cast Iron (Hard) .004-.010 .002-.006 .002-.006
Milt Steel .004-.010 .002-.007 .002-.010
Alloy Steel (Hard) .004-.010 .002-.007 .002-.006
Tool Steel .004-.008 .002-.006 .002-.006
Stainless Steel .004-.008 .002-.006 .002-.006
Titanium .004-.008 .002-.006 .002-.006
High Manganese Steel .004-.008 .002-.006 .002-.006
Note Double Speed for Carbide Cutting Tools Note Double Speed for Carbide Cutting Tools Note Double Speed for Carbide Cutting Tools Note Double Speed for Carbide Cutting Tools
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Example Feed Rate
Calculate the Feed Rate for End Milling Aluminum
with a 2 flute, ½ inch HSS end mill.
Fm ft x nt x N
ft.005 in. / tooth
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Example Feed Rate
Calculate the Feed Rate for End Milling Aluminum
with a 2 flute, ½ inch HSS end mill.
Fm ft x nt x N
ft.005 in. / tooth
nt 2 teeth
2000 rpm
Fm .005 x 2 x 2000
Fm 20 in/min.
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Your turn, ex. Feed Rate
Calculate the Feed Rate for Face Milling Aluminum
with a 4 flute, ¾ inch HSS end mill.
Fm ft x nt x N
ft.005 in. / tooth
nt 4 teeth
1333.33 rpm
Fm .005 x 4 x 1333.33
Fm 26.67 in/min.
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Factors That Affect Feed Rates

• Power of Spindle Motor
• Condition of Cutting Tool
• Depth of Cut
• Quality of surface finish required
• Roughing vs. Finish cuts
• Condition of the machine
• Strength of Fixture

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Tool Feed Rate for Holes
Penetration rate in inches/rev.
Tool Feed Rate (ipm) ipr x rpm
Feed in inches/min.
Spindle speed in rev./min.
Professional Development Lesson ID Code 6004
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Recommended Drilling Feeds
Drilling Feeds Drilling Feeds
Drill Diameter (in.) Drill Feed Rate (ipr)
lt ? .001-.002
? ¼ .002-.004
¼ - ½ .004 - .007
½ - 1 .007 - .015
gt 1 .015-.025
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Drill Feed Example
What tool feed rate should be used for drilling a
.375 inch hole in aluminum?
Tool Feed Rate (ipm) ipr x rpm
2,666 RPM
Drill feed ¼ - ½ diameter .004 - .007
Tool Feed Rate (ipm) .005 x 2,666
ipm 13.33
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Your Turn, Ex. Drill Feed
What tool feed rate should be used for drilling a
.25 inch hole in copper?
Tool Feed Rate (ipm) ipr x rpm
Drill feed ¼ - ½ diameter .004 - .007
Tool Feed Rate (ipm) .004 x 1,600
ipm 6.4
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Special Operations
Other Special Operations require slower
speeds Reaming ½ to ? of that used for
drilling the material Counterboring ¼ of that
used for drilling the material Countersinking ¼
of that used for drilling the material Tapping
(threading) determined by many factors
(usually range from 50 to 300 RPM)
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Curriculum Alignment
Unit 2 CNC Machining Section 2.5 Precision
Measurement
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References
Kibbe, R.R. Neely, J.E. Meyer, R.O. White,
W.T. (2002). Machine Tool Practices, Upper
Saddle River, NJ Prentice Hall. Oberg, E.
Jones F. D. Horton, H. L. Ryffell, H. H.
(2000). Machinerys Handbook, 26th ed., New
York, NY Industrial Press Inc.
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Credits
Writer Ken McDermith Content Editor Donna E.
Scribner Narration Donna E. Scribner PLTW
Editor Ed Hughes Production CJ Amarosa Video
Production CJ Amarosa Audio CJ Amarosa Project
Manager Donna E. Scribner