speeds and feeds
DESCRIPTION
Speeds and Feeds. In This Lesson. Discuss different cutting tools Learn the definition of speeds and feeds Calculate cutting speeds and feed rates Practice. Basic Cutting Tools. Non-Center Cutting End Mill. Ball End Mill. Center Cutting End Mill. Indexable Shell Mill. - PowerPoint PPT PresentationTRANSCRIPT
Speeds and Feeds
In This Lesson
• Discuss different cutting tools
• Learn the definition of speeds and feeds
• Calculate cutting speeds and feed rates
• Practice
Basic Cutting Tools
Center Cutting End
Mill
Ball End Mill
Non-Center Cutting End
Mill
Indexable Shell Mill
Basic Cutting Tools
Combination
Drill & Countersink
Spotting Drill
Countersink
Flutes
2 Flute End Mill
• More room for chip evacuation
• Used for light metals
• Weak, short tool life
4 Flute End Mill•More cutting edges, longer tool life
•Used for harder metals
•Clogs easily in deep cuts
Center vs. Non-Center Cutting
2 Flute Center Cutting
4 Flute Center Cutting
4 Flute Non-Center
Cutting
Milling ToolsTool Description Application
¼” 2 Flute HSS Single End Mills
For Cutting Aluminum – 3/8
Shank x 1 ¼ cutting length
Facing, profiling, Pocketing, Slotting,
Roughing and Finishing
¼” 2 Flute Ball End Mill for
Aluminum – 3/8 shank x 1 ¾
cutting length
Surfacing, Slotting, profiling,
Roughing and Finishing
Milling ToolsTool Description Application
¼” Countersink & De-burring
Tool – 90 Degree
Engraving, De-burring,
countersink, Spot drilling
#3 Combined drill &
countersink 90 Degree
Spot drilling, Engraving
Milling ToolsTool Description Application
¼” spotting drill 90 deg
Spot drilling, Engraving
Cutting Tool Material Video
Definitions
• Cutter Speed – The rate of a tool measured in surface feet per minute.
• Spindle Speed – The number of revolutions per minute (RPM) that is made by the cutting tool of a machine.
• Feed – The distance advanced by the cutting tool along the length of the work for every revolution of the spindle.
Spindle Feeds Formula• Defined in revolutions per minute (RPM)• Found by dividing the cutter speed by the
circumference of the tool
N =CS (ft/min)
C (in.)
N =CS 12 (in./min)
d (in.)
circumference
Recommended Cutting SpeedsMilling 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
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
CS 12 (in./min)
d (in.)N =
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
250 ft/min 12
0.5 in.N = 1910 RPM=
CS 12 (in./min)
d (in.)N =
Your TurnWhat spindle speed should be used to mill soft cast iron with a ¼ inch end mill?
Cutting speed for soft cast iron is 80 surface ft/min
80 12
0.250N = = 1222 RPM
CS 12 (in./min)
d (in.)N =
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 = CS 12 (in./min)
d (in.)
Recommended Tool FeedTool 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
Mild 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
Example Feed RateCalculate the feed rate for end milling aluminum with a 2 flute, ½ inch HSS end mill.
Fm = ft nt N
ft=.005 in./tooth
Tool Feed (in./tooth)
Example Feed RateCalculate the feed rate for end milling aluminum with a 2 flute, ½ inch HSS end mill.
Ft = 0.005 in./tooth
nt= 2 teeth
= 1910 RPM250 12
0.5=
Fm = 0.005 2 1910Fm = 19 in./min
Fm = ft nt N
CS 12 (in./min)
d (in.)N =
Your TurnCalculate the feed rate for face milling aluminum with a 4 flute, ¾ inch HSS end mill.
Ft = 0.005 in./tooth nt= 4 teeth
N = = 1273 RPM250 12 0.75
=
Fm = 0.005 4 1273
Fm = 25.46 in./min
Fm = ft nt N
CS 12 (in./min)
d (in.)
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
Tool Feed Rate for Holes
Tool Feed Rate (ipm) = ipr RPM
Feed in inches/minute
Penetration rate in inches/revolution
Spindle speed in revolutions/minute
Recommended Drilling Feeds
Drilling Feeds
Drill Diameter (in.) Drill Feed Rate (ipr)
< ⅛ .001 – .002
⅛ – ¼ .002 – .004
¼ – ½ .004 – .007
½ – 1 .007 – .015
> 1 .015 – .025
Drill Feed Example
250 12 0.375
= 2,546 RPM
What tool feed rate should be used for drilling a .375 inch hole in aluminum?
Tool Feed Rate (ipm) = ipr RPM
CS 12 (in./min)
d (in.)N =
=
Drill FeedThe tool diameter is given in decimal form
Drilling Feeds
Drill Diameter (in.)
Drill Feed Rate (ipr)
< 0.125 .001 – .002
0.125. – 0.25 .002 – .004
0.25 – 0.5 .004 – .007
0.5 – 1 .007 – .015
> 1 .015 – .025
The diameter is .375.
Tool Feed Rate (ipm) = ipr RPM = 0.005 2546 = 12.73 ipm
Your Turn
What tool feed rate should be used for drilling a .25 inch hole in copper?
Tool Feed Rate (ipm) = ipr x rpm
100 12 0.25
= 1,528 RPM
CS 12 (in./min)
d (in.)N =
=
Drill FeedDrilling Feeds
Drill Diameter (in.)
Drill Feed Rate (ipr)
< 0.125 .001 – .002
0.125. – 0.25 .002 – .004
0.25 – 0.5 .004 – .007
0.5 – 1 .007 – .015
> 1 .015 – .025
Our diameter is 0.25
Tool Feed Rate (ipm) = ipr RPM = 0.004 1528 = 6.1 ipm
Special Operations
Other special operations require slower speeds:
Reaming – ½ to ⅔ 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)
CS 12 (in./min)
d (in.)N =
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). Machinery’s handbook (26th ed.). New York, NY: Industrial Press Inc.