Transcript Speeds and Feeds - Mr. Meredith @ RHS

Speeds and Feeds
In This Lesson
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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 Tools
Tool
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 Tools
Tool
Description
Application
¼” Countersink
& De-burring
Tool – 90 Degree
Engraving, Deburring,
countersink,
Spot drilling
Spot drilling,
Engraving
#3 Combined
drill &
countersink 90
Degree
Milling Tools
Tool
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.)
circumference
N=
CS  12 (in./min)
d (in.)
Recommended Cutting Speeds
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
Example
What spindle speed should be used to
mill aluminum with a ½ inch end mill?
N=
CS  12 (in./min)
d (in.)
Cutting Speed for Aluminum is 250 surface ft/min
Example
What spindle speed should be used to
mill aluminum with a ½ inch end mill?
N=
CS  12 (in./min)
d (in.)
Cutting speed for aluminum is 250 surface ft/min
N =
250 ft/min  12
  0.5 in.
= 1910 RPM
Your Turn
What spindle speed should be used to mill
soft cast iron with a ¼ inch end mill?
N=
CS  12 (in./min)
d (in.)
Cutting speed for soft cast iron is 80 surface ft/min
N=
80  12
 0.250
= 1222 RPM
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 Feed
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
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 Rate
Calculate the feed rate for end milling aluminum
with a 2 flute, ½ inch HSS end mill.
Fm = ft  nt  N
Tool Feed (in./tooth)
ft=.005 in./tooth
Example Feed Rate
Calculate the feed rate for end milling aluminum
with a 2 flute, ½ inch HSS end mill.
Fm = ft  nt  N
Ft = 0.005 in./tooth
CS  12 (in./min)
250  12
N=
=
d (in.)
  0.5
nt= 2 teeth
Fm = 0.005  2  1910
Fm = 19 in./min
= 1910 RPM
Your Turn
Calculate the feed rate for face milling
aluminum with a 4 flute, ¾ inch HSS end mill.
Fm = ft  nt  N
Ft = 0.005 in./tooth
N=
nt= 4 teeth
CS  12 (in./min) 250  12
=
= 1273 RPM
d (in.)
  0.75
Fm = 0.005  4  1273
Fm = 25.46 in./min
Factors That Affect Feed Rates
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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
Penetration rate in
inches/revolution
Tool Feed Rate (ipm) = ipr  RPM
Feed in
inches/minute
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
What tool feed rate should be used for drilling
a .375 inch hole in aluminum?
Tool Feed Rate (ipm) = ipr  RPM
N=
=
CS  12 (in./min)
d (in.)
250  12
 0.375
= 2,546 RPM
Drill Feed
Drilling Feeds
Drill Diameter
Drill Feed
(in.)
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 tool diameter
is given in decimal
form
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
N=
=
CS  12 (in./min)
d (in.)
100  12
 0.25
= 1,528 RPM
Drill Feed
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
Our diameter is 0.25
Tool Feed Rate (ipm) = ipr  RPM
= 0.004  1528
= 6.1 ipm
Special Operations
N=
CS  12 (in./min)
d (in.)
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)
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.