1. Speeds and Feeds Speeds and Feeds CIM Product Development
See teacher notes for instructions on how to play videos referred to in this presentation.
Project Lead The Way, Inc.
Copyright 2008

2. In This Lesson Discuss different cutting tools
Learn the definition of speeds and feeds
Calculate cutting speeds and feed rates
Practice

3. Basic Cutting Tools Non-Center Cutting End Mill Ball End Mill
Indexable Shell Mill
Many different cutters are used during the milling process. The same cutting speed formula is used for each tool. Formula is presented on a subsequent slide.

4. Basic Cutting Tools Combination Drill & Countersink Spotting Drill

5. Flutes 4 Flute End Mill 2 Flute End Mill
More cutting edges, longer tool life
Used for harder metals
Clogs easily in deep cuts
More room for chip evacuation
Used for light metals
Weak, short tool life

6. Center vs. Non-Center Cutting
4 Flute Non-Center Cutting
2 Flute Center Cutting
4 Flute Center Cutting

7. 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

8. Milling Tools Tool Description Application
¼” Countersink & De-burring Tool – 90 Degree
Engraving, De-burring, countersink, Spot drilling
#3 Combined drill & countersink 90 Degree
Spot drilling, Engraving

9. Spot drilling, Engraving
Milling Tools
Tool
Description
Application
¼” spotting drill 90 deg
Spot drilling, Engraving

10. Cutting Tool Material Video
Speeds and Feeds
CIM
Product Development
Cutting Tool Material Video
Play video: Cutting Tool Material
Project Lead The Way, Inc.
Copyright 2008

11. Speeds and Feeds
CIM
Product Development
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.
Cutter speed must be converted to inches per minute so that it can be expressed as RPMs. This gives us the spindle speed.
Feed (or chipload) must be converted to inches per minute to give us the feed rate.
Project Lead The Way, Inc.
Copyright 2008

12. Spindle Feeds Formula Defined in revolutions per minute (RPM)
Speeds and Feeds
CIM
Product Development
Spindle Feeds Formula
Defined in revolutions per minute (RPM)
Found by dividing the cutter speed by the circumference of the tool
CS (ft/min)
C (in.)
N =
circumference
S, the cutting speed, is obtained from a machinery handbook.
A revolution is one complete rotation. This distance is called the circumference. The circumference of a circle is found by the formula d, where  is the constant value of approximately 3.14 and d is the diameter of the circle. In our formula, the diameter used is that of the tool being implemented.
Cutter speed is defined in feet per minute while circumference is defined in inches.
To convert so that the units match, we multiply feet by 12 since there are 12 inches in a foot.
Different materials use different spindle speed rates.
If the rate is too fast, the machine will wear out quickly. This can be expensive.
If the rate is too slow, time is wasted. With some materials, the tool can actually bond to the material at slow speeds. This can also be costly.
CS  12 (in./min)
d (in.)
N =
Project Lead The Way, Inc.
Copyright 2008

13. Recommended Cutting Speeds
Speeds and Feeds
CIM
Product Development
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
Alloy Steel (Hard) 40
Tool Steel
Stainless Steel 60
Titanium
High Manganese Steel 30
Note: Double Speed for Carbide Cutting Tools
Notice how the speeds are slower as you look down the chart. Why? The materials are harder as you move down the chart.
Project Lead The Way, Inc.
Copyright 2008

14. Example
What spindle speed should be used to mill aluminum with a ½ inch end mill?
CS  12 (in./min)
d (in.)
N =
Cutting Speed for Aluminum is 250 surface ft/min

15. Speeds and Feeds
CIM
Product Development
Example
What spindle speed should be used to mill aluminum with a ½ inch end mill?
CS  12 (in./min)
d (in.)
N =
Cutting speed for aluminum is 250 surface ft/min
Start with the formula and substitute the known values.
250 ft/min  12
  0.5 in.
N = =
1910 RPM
Project Lead The Way, Inc.
Copyright 2008

16. Your Turn
What spindle speed should be used to mill soft cast iron with a ¼ inch end mill?
CS  12 (in./min)
d (in.)
N =
Cutting speed for soft cast iron is 80 surface ft/min
80  12
N =
= 1222 RPM
 0.250

17. 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
CS  12 (in./min)
d (in.)
N = Spindle speed =

18. Recommended Tool Feed Speeds and Feeds CIM Product Development
Tool Feed (in./tooth)
Material
Face Mill
Side Mill
End Mill
Magnesium
Aluminum
Brass and Bronze
Copper
Cast Iron (Soft)
Cast Iron (Hard)
Mild Steel
Alloy Steel (Hard)
Tool Steel
Stainless Steel
Titanium
High Manganese Steel
Note: Double Speed for Carbide Cutting Tools
Notice that there are three feeds for each material, depending on whether it is a face mill, a side mill, or an end mill. Also, each material has a range of values attached to it. Typically, you will use the smallest value to be on the safe side.
Project Lead The Way, Inc.
Copyright 2008

19. Example Feed Rate Fm = ft  nt  N
Speeds and Feeds
CIM
Product Development
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)
HSS stands for high speed steel. What is the tool feed for aluminum?
ft=.005 in./tooth
Project Lead The Way, Inc.
Copyright 2008

20. Example Feed Rate Fm = ft  nt  N Fm = 0.005  2  1910
Calculate the feed rate for end milling aluminum with a 2 flute, ½ inch HSS end mill.
Fm = ft  nt  N
Ft = in./tooth
CS  12 (in./min)
d (in.)
250  12
N = =
= 1910 RPM
  0.5
nt= 2 teeth
Fm =  2  1910
Fm = 19 in./min

21. Your Turn Fm = ft  nt  N Fm = 0.005  4  1273 Fm = 25.46 in./min
Speeds and Feeds
CIM
Product Development
Your Turn
Calculate the feed rate for face milling aluminum with a 4 flute, ¾ inch HSS end mill.
Fm = ft  nt  N
Ft = in./tooth
nt= 4 teeth
CS  12 (in./min)
d (in.)
250  12
  0.75 =
N =
= 1273 RPM
1273 has been rounded. It is actually customary to wait until the last step to round.
Fm =  4  1273
Fm = in./min
Project Lead The Way, Inc.
Copyright 2008

22. Factors That Affect Feed Rates
Speeds and Feeds
CIM
Product Development
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
We can mathematically calculate the feed rates, but other factors affect the speed rate as well. If your tool is dull, for example, it will cut slower.
Project Lead The Way, Inc.
Copyright 2008

23. Tool Feed Rate for Holes
Speeds and Feeds
CIM
Product Development
Tool Feed Rate for Holes
Penetration rate in inches/revolution
Tool Feed Rate (ipm) = ipr  RPM
Feed in inches/minute
The penetration rate is referred to as the drill feed.
Spindle speed in revolutions/minute
Project Lead The Way, Inc.
Copyright 2008

24. Recommended Drilling Feeds
Speeds and Feeds
CIM
Product Development
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
Again, we have a range of values for each diameter. Notice that the diameters are also in ranges of values.
Project Lead The Way, Inc.
Copyright 2008

25. Speeds and Feeds
CIM
Product Development
Drill Feed Example
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 =
We will find RPM first since we have had prior experience with it.
250  12 =
 0.375
= 2,546 RPM
Project Lead The Way, Inc.
Copyright 2008

26. Drill Feed The tool diameter is given in decimal form Drilling Feeds
Speeds and Feeds
CIM
Product Development
Drill Feed
Drilling Feeds
Drill Diameter (in.)
Drill Feed Rate (ipr)
< 0.125
.001 – .002
– 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.
To find the drill feed, we need to know where .375 inches falls on the chart. The easiest way to do this is to convert the chart to decimals, since these are common values.
Since .375 is slightly larger than .25, we will choose a number higher than .004
We choose .005 (we could have chosen .004 to be on the safe side).
Our drill feed would be inches per minute.
Tool Feed Rate (ipm) = ipr  RPM
=  2546
= ipm
Project Lead The Way, Inc.
Copyright 2008

27. Your Turn
What tool feed rate should be used for drilling a .25 inch hole in copper?
Tool Feed Rate (ipm) = ipr x rpm
CS  12 (in./min)
d (in.)
N =
100  12 =
 0.25
= 1,528 RPM

28. Drill Feed Our diameter is 0.25 Tool Feed Rate (ipm) = ipr  RPM
Speeds and Feeds
CIM
Product Development
Drill Feed
Drilling Feeds
Drill Diameter (in.)
Drill Feed Rate (ipr)
< 0.125
.001 – .002
– 0.25
.002 – .004
0.25 – 0.5
.004 – .007
0.5 – 1
.007 – .015
> 1
.015 – .025
Our diameter is 0.25
Since .25 is a limit, we choose the value assigned to it. In either case, that value is 0.25.
Tool Feed Rate (ipm) = ipr  RPM
=  1528
= 6.1 ipm
Project Lead The Way, Inc.
Copyright 2008

29. Special Operations CS  12 (in./min) N = d (in.)
Speeds and Feeds
CIM
Product Development
Special Operations
CS  12 (in./min)
d (in.)
N =
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)
There are some circumstances that require speeds slower than the one obtained from the formula.
In tapping, there is no special formula.
Project Lead The Way, Inc.
Copyright 2008

30. 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.