The intention of this report is to briefly, explain some of the machining operations that are involved in the process of TURNING, these are: Cutting Speed, Depth of Cut, Feed Rate and Spindle Speed. Also demonstrated will be the mathematical calculations involved in the same process, using various equations.

1. 2009
HNC CAD/CAM
SOFTWARE APPLICATIONS ASSINGMENT
“TURNING”
David Antuna
GSD
11/25/2009

2. HNC CAD/CAM SOFTWARE APPLICATIONS DAVID ANTUNA
Table of Contents:
Summary: ................................................................................................................................... 3
1. Introduction. ....................................................................................................................... 4
2. Feed rate. ............................................................................................................................ 5
3. Spindle speed...................................................................................................................... 6
4. Depth of Cut. ...................................................................................................................... 6
5. Cutting speed. ..................................................................................................................... 7
5.1 Work Piece Drawing. . ................................................................................................. 9
5.2 Calculation of Optimum Cutting Speeds. ..................................................................... 10
6. Calculation of Power Required for Machining Operations. ............................................. 12
7. Conclusion: ....................................................................................................................... 14
8. References: ....................................................................................................................... 15
9. Report Definitions: ........................................................................................................... 16
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3. HNC CAD/CAM SOFTWARE APPLICATIONS DAVID ANTUNA
Summary:
The intention of this report is to briefly, explain some of the machining operations that are
involved in the process of TURNING, these are: Cutting Speed, Depth of Cut, Feed Rate and
Spindle Speed.
Also demonstrated will be the mathematical calculations involved in the same process,
using various equations.
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4. HNC CAD/CAM SOFTWARE APPLICATIONS DAVID ANTUNA
1. Introduction:
The phrase speeds and feeds (or feeds and speeds) refers to two separate velocities in
machine tool practice, cutting speed and feed rate. (Brown & Sharpe, Automatic Screw Machine
Hand book :) They are often considered as a pair because of their combined effect on the
cutting process. Each, however, can also be considered and analyzed in its own. Cutting
speed is the speed difference between the cutting tool and the surface of the work piece it
is operating on, It is expressed in units of distance along the work piece surface per time.
Feed rate is the velocity at which the cutter is fed, that is, advanced against the work piece.
It is expressed in units of distance per revolution for turning and boring (typically inches per
revolution (ipr) or millimetres per revolution). It can be expressed thus for milling also, but it
is often expressed in units of distance per time for milling (typically inches per minute [ipm]
or millimetres per minute). Cutting speed and feed rate together determine the material
removal rate, which is the volume of work piece material (metal, wood, plastic, etc.) that
can be removed per time unit.
If variables such as cutter geometry and the rigidity of the machine tool and its tooling setup
could be ideally maximized (and reduced to negligible constants), then the amount of power
(that is, kilowatts or horsepower) available to the spindle would determine the maximum
speeds and feeds possible for any given work piece material and cutter material. Of course,
in reality those other variables are dynamic and not negligible; but there is still a correlation
between power available and feeds and speeds employed.
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5. HNC CAD/CAM SOFTWARE APPLICATIONS DAVID ANTUNA
2. Feed rate.
Feed rate is the velocity at which the cutter is fed, (Brown & Sharpe, Automatic Screw Machine Hand
book :) that is, advanced against the work piece. It is expressed in units of distance per
revolution for turning and boring (typically inches per revolution [ipr] or millimeters per
revolution). It can be expressed thus for milling also, but it is often expressed in units of
distance per time for milling (typically inches per minute [ipm] or millimeters per minute),
with considerations of how many teeth (or flutes) the cutter has then determining what that
means for each tooth.
Feed rate is dependent on the:
 Surface finish desired.
 Power available at the spindle (to prevent stalling of the cutter or work piece).
 Rigidity of the machine and tooling setup (ability to withstand vibration or chatter).
 Strength of the work piece (high feed rates will collapse thin wall tubing)
 Characteristics of the material being cut, chip flow depends on material type and
feed rate. The ideal chip shape is small and breaks free early, carrying heat away
from the tool and work.
When deciding what feed rate to use for a certain cutting operation, the calculation is fairly
straightforward for single-point cutting tools, because all of the cutting work is done at one
point (done by "one tooth", as it were). With a milling machine or jointer, where multi-
tipped/multi-fluted cutting tools are involved, then the desirable feed rate becomes
dependent on the number of teeth on the cutter, as well as the desired amount of material
per tooth to cut (expressed as chip load). The greater the number of cutting edges, the
higher the feed rate permissible: for a cutting edge to work efficiently it must remove
sufficient material to cut rather than rub; it also must do its fair share of work.
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6. HNC CAD/CAM SOFTWARE APPLICATIONS DAVID ANTUNA
3. Spindle Speed.
The spindle speed is the rotational frequency of the spindle of the machine, (Brown & Sharpe,
Automatic Screw Machine Hand book :) measured in revolutions per minute (RPM). The preferred
speed is determined by working backward from the desired surface speed (sfm or m/min)
and incorporating the diameter (of work piece or cutter).
The spindle may hold the:
 Drill bit in a drill
 Milling cutter in a milling machine
 Router bit in a wood router
 Shaper cutter or knife in a wood shaper or spindle moulder
 Grinding wheel on a grinding machine.
 Or it may hold the chuck which then holds the work piece in a lathe. In these cases
the tool bit remains stationery although exceptions may be found such as in thread
milling.
4. Depth of Cut:
The easiest cutting parameter to adjust is the depth of cut. (Fox Valle Technical College. Machine
Shop) Doubling the depth of cut in a turning operation will double the metal removal rate
without any increase in cutting temperature. The horsepower consumed will virtually
double, but there will be no reduction in tool life (specific wear per inch of cutting edge
length) assuming the cutting edge can withstand the added tangential cutting force.
However, it is not always possible to increase the depth of cut to gain additional
productivity, since there might not be any remaining material to remove.
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7. HNC CAD/CAM SOFTWARE APPLICATIONS DAVID ANTUNA
5. Cutting Speed:
Cutting speed may be defined as the rate (or speed) that the material moves past the
cutting edge of the tool, (Brown & Sharpe, Cam & Tool Design: Surface Cutting Speeds Chart, p. 5)
irrespective of the machining operation used — the surface speed. A cutting speed for mild
steel, of 100 ft/min (or approx 30 meters/min) is the same whether it is the speed of the
(stationary) cutter passing over the (moving) work piece, such as in a turning operation, or
the speed of the (stationary) work piece moving past a (rotating) cutter, such as in a milling
operation. What will affect the value of this surface speed for mild steel, is the cutting
conditions:
For a given material there will be an optimum cutting speed for a certain set of machining
conditions, and from this speed the spindle speed (RPM) can be calculated. Factors affecting
the calculation of cutting speed are:
 The material being machined (steel, brass, tool steel, plastic, wood) (see table below)
 The material the cutter is made from (Carbon steel, High speed steel (HSS), carbide,
ceramics)
 The economical life of the cutter (the cost to regrind or purchase new, compared to
the quantity of parts produced).
Cutting speeds are calculated on the assumption that optimum cutting conditions exist,
these include:
 Metal removal rate (finishing cuts that remove a small amount of material may be
run at increased speeds)
 Full and constant flow of cutting fluid (adequate cooling and chip flushing)
 Rigidity of the machine and tooling setup (reduction in vibration or chatter)
 Continuity of cut (as compared to an interrupted cut, such as machining square
section material in a lathe)
 Condition of material (mill scale, hard spots due to white cast iron forming in
castings)
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8. HNC CAD/CAM SOFTWARE APPLICATIONS DAVID ANTUNA
The cutting Speed is given as a set of constants that are available from the material
manufacturer or supplier, the most common materials are available in reference books, or
charts but will always be subject to adjustment depending on the cutting conditions. The
following table gives the cutting speeds for a selection of common materials under one set
of conditions. The conditions are a tool life of 1 hour, dry cutting (no coolant) and at
medium feeds so they may appear to be incorrect depending on circumstances. These
cutting speeds may change if, for instance, adequate coolant is available or an improved
grade of HSS is used (such as one that includes cobalt).
Cutting speeds for various materials (Based on a plain High Speed Steel cutter)
Material type meters per min feet per min
Steel (tough) 15 - 18 50 - 60
Mild steel 30-38 100-125
Cast iron (medium) 18-24 60-80
Bronzes 24-45 80-150
Brass (soft) 45-60 150-200
Aluminium 75-105 250-350
Table 1 Cutting Speeds Parameters.
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9. HNC CAD/CAM SOFTWARE APPLICATIONS DAVID ANTUNA
5.1 Work piece Drawing:
The following diagram shows an example of work piece that could be machine/turn in a lathe.
This drawing was made using the design software AUTO CAD.
Table 2 Process of Turning
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10. HNC CAD/CAM SOFTWARE APPLICATIONS DAVID ANTUNA
5.2 Calculation of Optimum Cutting Speeds:
The following are the results from the calculations made for the cuttings speeds displayed
below.
The calculations where made using the following equation:
������������������������ ������������������������
RPM = =
������������������������������������������������������������������������������ ������������������������������������������������������������
CALCULATION OF OPTIMUM CUTTING SPEEDS FOR HARDENED STEEL
DIAMETER OF SHAFT IN MM FEED RATE IN MM/Min. RPM
20 15000 238.7324146
40 15000 119.3662073
60 15000 79.57747155
CALCULATION OF OPTIMUM CUTTING SPEEDS FOR BRONZE
DIAMETER OF SHAFT IN MM FEED RATE IN MM/Min. RPM
20 24000 381.9718634
40 24000 190.9859317
60 24000 127.3239545
CALCULATION OF OPTIMUM CUTTING SPEEDS FOR BRASS
DIAMETER OF SHAFT IN MM FEED RATE IN MM/Min. RPM
20 45000 716.1972439
40 45000 358.098622
60 45000 238.7324146
CALCULATION OF OPTIMUM CUTTING SPEEDS FOR ALUMINIUM
DIAMETER OF SHAFT IN MM FEED RATE IN MM/Min. RPM
20 75000 1193.662073
40 75000 596.8310366
60 75000 397.8873577
10

11. HNC CAD/CAM SOFTWARE APPLICATIONS DAVID ANTUNA
This scatter graph displays the optimum cutting speeds for the various metals shown in this
report.
CUTTING SPEEDS
1400
1200
HARDENED
STEEL
1000
BRONZE
800
BRASS
R
P
M
600 ALUMINIUM
400
200
0
0 10 20 30 40 50 60 70
DIAMETER OF SHAFT IN MM
Table 3 Cutting Speed Calculations.
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12. HNC CAD/CAM SOFTWARE APPLICATIONS DAVID ANTUNA
6. Calculation of Power Required for Machining Operations.
The table below displays the results of the calculations of the power required to turn Ø100
mm bar at the various speeds.
The following equation was used:
������������������������������ ������ ������������������������������������������ ������ ������������������������������������������������������(������������������ ������������������ ������������������)
Power (W) =
������������
CALCULATION OF POWER REQUIRED FOR CUTTING OPERATIONS
SPEED IN
DIM. OF SHAFT IN MM RADIUS OF SHAFT IN MM REV/MIN CUTTING FORCE IN (N) POWER
100 0.05 40 350 73.30
100 0.05 80 350 146.61
100 0.05 160 350 293.22
100 0.05 320 350 586.43
POWER REQUIRED FOR MACHINING
OPERATIONS
700.00
600.00
P
500.00
O Power
400.00
W steel
300.00
E
200.00 Bronze
R
100.00 Brass
0.00
Aluminium
0 50 100 150 200 250 300 350
SPEED IN REV PER MIN.
Table 4 Power Required for Machining Operation
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13. HNC CAD/CAM SOFTWARE APPLICATIONS DAVID ANTUNA
As we can see from the table above, the higher the revolution per minute the higher the
power is required to cut/machine an object, in this case a solid shaft of 100mm of diameter.
These actions also influences on the tool life, the reason is simple, as it is stated above, the
higher the revs/min the higher the power is required therefore the harder the tool has to
work.
In this report we have taken four kinds of metal, hardened steel, bronze, brass and
aluminium, so if bronze is taking as a example we can deduct that it will be harder to
machine, therefore it will need a low set of feed and speed and doing so it will required just
the correct amount of power to do the job.
A company that it’s main activity is machining parts, i.e. A nuts and bolts factory, will
depend in it’s ability to maximize the use of the cutting tools, therefore all the machinery
must work with the optimum set up (cutting speed, feed rate & depth of cut) to make the
most of every cutting tool.
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14. HNC CAD/CAM SOFTWARE APPLICATIONS DAVID ANTUNA
7. Conclusion:
In this report we have learned that in the process of cutting/machining in the context of
TURNING, there is a very fine balance between setting up the optimum cutting speed, feed
rate and depth of cut. This balance if is apply correctly it should create the maximum level of
working condition to obtain the best results from the job in hand.
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15. HNC CAD/CAM SOFTWARE APPLICATIONS DAVID ANTUNA
8. References:
World Wide In-Text Reference End Note
Web Example List Example
Document on The phrase Brown & Electronic Source
WWW speeds and Sharpe, Wikipedia the free Encyclopedia.
feeds refers to Automatic 26 Nov. 2009 (last revision)
two separate Screw Machine
velocities in Handbook: http://en.wikipedia.org/wiki/Feed_rate
machine tool Brown and
practice. Sharpe Speeds
and Feeds
Chart, p. 222 &
223
Document on Feed rate is Brown & Electronic Source
WWW the velocity at Sharpe, Wikipedia the free Encyclopedia.
which the Automatic 26 Nov. 2009 (last revision)
cutter is fed. Screw Machine
Handbook: http://en.wikipedia.org/wiki/Feed_rate
Document on The spindle Brown & Electronic Source
WWW speed is the Sharpe, Wikipedia the free Encyclopedia.
rotational Automatic 26 Nov. 2009 (last revision)
frequency of Screw Machine. http://en.wikipedia.org/wiki/Spindle_speed
the spindle of
the machine.
Document on The easiest Fox Valle Electronic Source
WWW cutting Technical Put on Fox Valle Technical College in year 2000.
parameter to College. http://its.fvtc.edu/machshop4/Carbcut/Cutspeeds.htm
adjust is the Machine Shop
depth of cut. web pages.
Document on Cutting speed Brown & Electronic Source
WWW may be Sharpe, Cam & Wikipedia the free Encyclopedia.
defined as the Tool Design: 26 Nov. 2009 (last revision)
rate (or speed) Surface Cutting http://en.wikipedia.org/wiki/Cutting_speed
that the Speeds Chart, p.
material 5
moves past
the cutting
edge of the
tool.
Picture on the The term Copyright © Electronic Source
2009 eFunda,
WWW "facing" is Inc.
Efunda TURNING
used to
describe http://www.efunda.com/processes/machining/turn.cfm
removal of
material from
the flat end of
a cylindrical
part.
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16. HNC CAD/CAM SOFTWARE APPLICATIONS DAVID ANTUNA
9. Report Definitions:
The following is a list of definitions of the structural points that composed this report.
Title Page: The Title page is the very first page of a report and can be composed form
only text with the information about the course to a very elaborate visual page with
colour and pictures about the subject in the report.
Summary: The summary is a shorten version of the subject that has been said or
written in a report or a discussion, containing only the main points.
Table of Contents: This is the page where the content of a report is listed, including
pictures, graphs, tables and external work, all it is shown with its page number.
Introduction: The introduction is the section at the beginning of a report that
summarizes what it is about, also gives the reader the basic facts or skills in a field.
Body/Discussions: This is the main part of a report, when the subject in the report is
presented with all its facts, all the research done and all the support work. i.e.
graphs, tables, photographs etc...
Conclusions: This is the part in a report where after looking in to all the discussions
within the report it brings it in to a formal closure.
References: The reference states to the reader in a list or table of all the information
use to help to complete the report from authors other that the creator of the report.
Appendices: This part in the document is where is set all the separate material that
are part of the report but it has not been made by the creator of the same.
Acknowledgments: In this section of the report the author thanks those who have
help in the making of the report.
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