2.
Title of Master Project
Influence of Drilling Parameters on
Burr Formation & Size for
Low Carbon Steel & Stainless Steel
3.
Drilling is a machining process used to create or
enlarge holes into or through a work piece material.
This process is performed with the use of a drill,
which works by rotating at a high speed while
simultaneously being fed into the work piece,
removing incremental amounts of work piece
material.
Drilling Process
4.
During the drilling
process, burrs raised on
the entry and exit surfaces
as a result of plastic
deformation of the work
piece material.
Burrs are small amounts of
attached material that
obtrude from the original
entry and exit surfaces
around the drilled hole.
Burr Deformation
Burr Deformation
5.
Burrs are generally unwanted and need to be
removed by extra machining process depending on
the specific desired part geometry.
The formation of burrs and the resulting deburring
operations that need to be performed can be very
costly and reach to 30% of the total machining cost
and is time-consuming in operation.
Deburring Process
6.
If they are not removed, they can cause misalignment
with adjacent parts.
Because of strain-hardening effects, burrs are more
harder than the original material ,meaning that
contact between two adjacent parts with the burr in
between can cause cracks and can reduce the overall
fatigue life of the assembly.
The burrs can also get a small gap from the surface
and get trapped between mating surfaces leading to
three-body abrasion and eventual failure of the
assembly
Burr Defects & Problems
12.
Factors Affecting Drilling
categorized five criteria for measuring drill performance
including speed, drill life, efficiency of metal removal,
hole accuracy, and hole surface finish, and listed over 60
factors that can affect those criteria divided into the
properties of the drill, work piece, machine, and drilling
conditions.
Previse Studies
13.
Other problems include the introduction of stress risers in
critical areas, operator danger of getting cut by sharp burrs,
and poor part aesthetics.
Additional problems are caused when burrs break off and
move between assembled parts. the relative motion of the
burr trapped between mating surfaces can cause cracks to
form.
For industrial situations, deburring costs vary depending
on the specific application and deburring method used. It
has also been reported that deburring costs associated with
removing interlayer burrs from aircraft structures can
account for up to 30% of total manufacturing costs.
The danger from not removing interlayer burrs from
aircraft is that serious structural safety problems can occur.
Previse Studies
14.
Many investigations have studied the effects of
drilling spindle speeds and feed rates on the resulting
burr sizes.
Many studies have all shown that lower feed rates
tend to reduce burr heights and/or thicknesses.
Fewer experiments have been performed and fewer
conclusive results have been made regarding changes
in spindle speed.
Experimental Investigations –
Drilling Parameters
15.
The two most commonly varied drilling geometry
parameters in burr studies are the helix angle and
point angle.
Multiple studies have shown that higher helix angles
tend to reduce burr heights.
It has also been commonly observed that lower
(steeper) point angles tend to minimize burrs.
Experimental Investigations –
Drilling Geometries
16.
Very few investigations have been made regarding
the relationship between drill wear and burr sizes.
One study found that drill wear does significantly
increase the sizes of burrs for miniature holes.
Regarding the work piece material properties, it is
commonly known that higher material ductility
values result in larger burrs due to the smaller forces
required for plastic deformation. Another study also
found that higher work piece hardness values, result
in lower burr thicknesses.
Experimental Investigations –
Wear and Work piece Material
18.
Abstract
In this research an experimental investigation will be
done on the influence of main drilling parameters on
burr formation in machining low carbon steel and
stainless steel by using (High Speed Steel) HSS
cutting tools and cooling fluid.
Particular attention will be focused on the relation
between the burr height with drilling parameters.
Therefore, a wide range of spindle speeds and feed
rates will be investigated to explore the optimum
drilling conditions.
19.
Abstract
Burr heights will be measured and analyzed at
different drilling conditions to determine the effect
of drilling speed and feed rate on burr formation.
The data obtained for low carbon steel will be
compared with those for stainless steel.
Different diameters of HSS twist drill and work piece
thickness will be used to observe their effects on
drilling burr formation.
20.
Parameter Selection
There are many drilling parameters take as
influential factors on burr formation.
These effects include drilling spindle speeds, feed
rates and diameter sizes on the resulting burr height
as well as the effect of material specifications and
work piece geometry on the burr formation.
21.
Diameter Sizes
it was decided that a total of five different drill sizes
would be used.
No more than five different drill sizes were used due
to the extensive time required to run tests
throughout the drill lifetimes.
high range of different diameters will be chosen to
evaluate clearly the effect of increasing the diameter
on the burr height.
24.
Spindle Speeds and Feed Rates
Many investigations have studied the effects of
drilling feed rates and spindle speeds on the
resulting burr height.
The feed per revolution is the most commonly
experimentally varied parameter.
four different values of feed rate and other four
different values of spindle speed were chosen to
evaluate the effect of each of these factors on the burr
deformation.
25.
Spindle Speeds and Feed Rates
Feed Rate
(rev/mm)
0.11 0.13 0.15 0.18
Speed
(rpm)
160 170 180 200
Table 2: Values of feed rate and Spindle Speed
26.
Material Specifications
The work materials investigated in this work are hot
rolled low carbon steel (LCS), ST37, and cold rolled
stainless steel (SS), AISI316 and both materials are in
the annealed condition.
These materials were selected because they are
widely used in industry for production purposes by
drilling operations.
27.
Material Specifications
Work Material Type C% P% S% Mn% Si% Cr% Ni% N%
Low Carbon Steel
(ST37)
Max
0.17
Max
0.045
Max
0.045
Max
1.25
Max
0.045
- -
Max
0.01
Stainless Steel
(AISI316)
Max
0.08
Max
0.045
Max
0.030
Max
2.00
Max
0.75
18.00-
20.00
8.00-
12.00
Max
0.01
Table 3: Chemical compositions of the work materials (produced by the
material manufacturers in wt% for each element).
28.
Material Specifications
Property
Material
Yield Strength
(MPa) min
Tensile Strength
(02%proof)
(MPa) min
Elongation
(% in 50 mm)
min
Brinell (HB)
Hardness max
Stainless Steel
(AISI316)
205 515 40 217
Low Carbon Steel
(ST37)
210 380 25 108
Table 4: Mechanical properties of work materials.
29.
Material Geometry
Rectangular blocks 500 mm in length, 240 mm in
width, and two different thicknesses 10 mm and 16
mm from these materials were used for studying the
burr formation in drilling operations.
The two different thicknesses were given indication
about thicknesses effect on the burr deformation.
The work piece was designed to cover all selected
parameters to be studied in this experiment.
31.
Material Geometry
the hole is repeated three times with the same
conditions to eliminate any chances of foreign
reading of burr deformation height.
The little polishing for each face of work piece is
done by a value of 0.3 mm. The polish helps reduce
the burr deformation that will appear and make the
work piece surface as a standard face in measuring
procedure.
32.
Experimental Procedure
In this experiment semi-synthetic coolants, also
called "soluble oil," are used with constant flow rate
for all work pieces and for all experiments.
holes were drilled in a DMC 635 V CNC vertical
machining center.
34.
Burr Height Measurements
Skin exit burr were measured once for each hole.
There were 33 holes for each work piece and the total
number of holes for all four work pieces are 132
holes with the same quantity of readings.
The method involved measuring the burr heights
using a digital depth caliper.
36.
Experiments Results & Discussions
The effects of various drilling condition parameters
on burr sizes were identified will be shown in 3
stages:
1. Diameter Effect on Burr Height
2. Feed Rate Effect on Burr Height
3. Spindle Speed Effect on Burr Height
With more discussions about the effect of material
proparties and thickness in each stage.
37.
1-Diameter Effect on Burr Height
0
0.5
1
1.5
2
2.5
3
3.5
10 15 20 25 30 35 40 45
BURRHEIGHT(mm)
HOLE DIAMETER (mm)
BURR HEIGHT (mm) SS BURR HEIGHT (mm) CS
Figure 1: Compare the effect of hole diameter on burr height for 10 mm
blocks of low carbon steel and Stainless Steel
38.
1-Diameter Effect on Burr Height
In figure 1 the graph shows, it is clear that increasing
in hole diameters make the burr height deformation
values rise higher. This is done with fixed values of
feed rate on 0.15mm/rev and spindle speed on 180
rpm.
This is apparent when the amount of material
increases together with big diameter hole sizes and
the temperature rises up due to the difficulties which
appear with large diameters producing the
deformation by its height values.
39.
1-Diameter Effect on Burr Height
The sharp increase in burr height in stainless steel
block needs more investigation and study by
referring to the wide range of drill diameters that
were chosen in experiments with fixing values of
feed rates and spindle speed along that range.
The same experiment and comparison was done for
blocks of 16mm thick of low carbon steel and
stainless steel, the carves follow approximately the
same path like 10mm thick blocks, as shown in
figure 2 for low carbon steel.
40.
1-Diameter Effect on Burr Height
Figure 2 : The effect of block thicknesses with the change of hole diameters on
burr height for low carbon steel
0
0.2
0.4
0.6
0.8
1
1.2
1.4
10 15 20 25 30 35 40 45
BURRHEIGHT(mm)
HOLE DIAMETER (mm)
BURR HEIGHT (mm) FOR 10 mm BURR HEIGHT (mm) FOR 16 mm
41.
1-Diameter Effect on Burr Height
It is evident that the small rise up in burr height
values come from the fact of the long time drilling
operation, where the high value of thickness
increases the time of drilling required, along with a
constant value of coolant feed rate that increases the
temperature due to the drilling operation as well as
an increase in burr deformation values.
42.
2-Feed Rate Effect on Burr Height
Figure 3 : Compare the effect of feed rate on burr height for 10 mm blocks of
low carbon steel and Stainless Steel
0.5
1
1.5
2
2.5
3
3.5
0.1 0.12 0.14 0.16 0.18 0.2
BURRHEIGHT(mm)
FEED RATE (mm/rev)
BURR HEIGHT (mm) SS BURR HEIGHT (mm) CS
43.
2-Feed Rate Effect on Burr Height
In the figure 3, In general, the increasing in feed rate
values that make the burr height deformation values
increased. This is done by fixing the hole diameter
on 40 mm and spindle speed on 180 rpm.
The hardness values of both materials and the effect
of the time of drilling operation with this parameter
that is removing the same amount of material with
time differences.
The increasing in feed rate values reduce the time of
drilling operation and produces the burr
deformation by its values and these values come
higher than results in diameter experiments.
44.
2-Feed Rate Effect on Burr Height
The burr height curve sharply increases for stainless
steel to become near three times bigger than low
carbon steel in use 0.15mm/rev and 0.18mm/rev.
The sharp increase in burr deformation height in the
stainless steel block indicate that there is a critical
value of feed affecting a certain factor on burr values
and this needs more investigation.
45.
2-Feed Rate Effect on Burr Height
Figure 4 : The effect of block thicknesses with the change of feed rate on burr
height for stainless steel
0.5
1
1.5
2
2.5
3
3.5
0.1 0.11 0.12 0.13 0.14 0.15 0.16 0.17 0.18 0.19
BURRHEIGHT(mm)
FEED RATE (mm/rev)
BURR HEIGHT (mm) FOR 10 MM BURR HEIGHT(mm) FOR 16 MM
46.
2-Feed Rate Effect on Burr Height
The same experiment and comparison was done for
blocks of 16mm thick of low carbon steel and
stainless steel, the carves follows the same path look
like 10mm thick blocks. As shown in figure 4
It is apparent that the small rise up in burr height
values come from the longtime drilling operation,
where the high value of thickness increases the time
of drilling required, along with a constant value of
coolant feed rate that increases the temperature from
drilling operation as well as an increase in burr
deformation values.
47.
3-Spindle Speed Effect
on Burr Height
Figure 5 : Compare the effect of spindle speed on burr height for 10 mm
blocks of low carbon steel and Stainless Steel
0
0.5
1
1.5
2
2.5
3
3.5
4
155 160 165 170 175 180 185 190 195 200 205
BURRHEIGHT(mm)
SPINDLE SPEED (rpm)
BURR HEIGHT (mm) SS BURR HEIGHT(mm) CS
48.
3-Spindle Speed Effect
on Burr Height
The graph in figure 5, The increase of spindle speed
values raise up the burr height deformation values.
By fixing the hole diameter on 40 mm and feed rate
on 0.15 mm/rev. the burr height gets the highest
values with the spindle speed 200 rpm in carbon
steel block.
The spindle speed gives the highest burr height
values owing to material hardness, temperature of
drilling operation, time of operation and the material
resisting to plastic deformation.
49.
3-Spindle Speed Effect
on Burr Height
The effect of block thickness for stainless steel with
the change of spindle speed values are shown in
figure 6.
The high value of thickness increases the time of
drilling required, along with a constant value of
coolant feed rate that increases the temperature from
drilling operation as well as with an increase in burr
deformation values.
50.
3-Spindle Speed Effect
on Burr Height
Figure 6 : The effect of block thicknesses with the change of spindle speed on
burr height for stainless steel
0
0.5
1
1.5
2
2.5
3
3.5
4
155 160 165 170 175 180 185 190 195 200 205
BURRHEIGHT(mm)
SPINDLE SPEED (rpm)
BURR HEIGHT(mm) FOR 10 MM BURR HEIGHT(mm) FOR 16 MM
51.
Calculations
The drill with a large diameter provides a higher exit
burr height and this normally due to more material
to be removed by plastic deformation owing to
higher thermal and cutting forces effects during the
drilling operations.
In the drill diameter experiment, the constant values
of feed rate and spindle speed was more suitable for
stainless steel plates but that changed with large
diameter values.
The wide range of diameters chosen in this
experiment gives a clear picture about the increase in
exit burr height deformation.
52.
Calculations
The drill operation with high value of feed rate
provides a higher exit burr height. This appears
because the time of drilling operation is reducing, so
as to remove the same amount of material that
increases thermal and cutting forces.
The feed rate affected more than drill diameter. This
is clear by comparing values of exit burr heights.
The drill operation with high value of spindle speed
provides a higher exit burr height and this is
normally due to the increase in spindle speed facing
high resistance from material hardness that appears
as an increase in thermal and cutting forces.
53.
Calculations
The spindle speed is the most effective parameter in
our experiments. This is true be comparing the
values of exit burr height.
The stainless steel plates have more resistance to
plastic deformation than low carbon steel. This
appears in all values of exit burr height and refer to
high values of hardness and tensile strength.
54.
Calculations
Thickness as a parameter has a minor effect on exit
burr height in our experiments; the burr height
increases with thickness increase, this is because of
the constant feeding of coolant with two thickness
values.
Minimizing the burr deformation that can be done
by re-identifing the different parameters values of
drilling operation and that comes on account of the
time required and cost of drilling operation.
55.
Acknowledgements
I would like to thank the following people for their
support in the completion of this Project :
My research advisor, Dr. Dhia K. Suker, for his
constant support in guiding me in my work and
helping me to complete this project.
Prof. Dr. Muhammad N. Radhwi and Prof. Dr.
Ahmed F. Abdel Gawad for providing advice during
the master‘s program that contributed to the final
shape of this project.
Dr. Muhammad Al-Ashhab for teaching me the
Methods of Scientific Research and always being
available for help.
56.
Acknowledgements
My wife, for English language supervision and
support.
My engineer friends, Bassam H. Tayeb, Yusif S. Al-
Qurashi and Mohammed Al-Hussaini for regularly
providing assistance and helpful insight.
The FINE TOOL Manufacturing Factory for their
support and manufacturing of samples.
The Saline Water Conversion Corporation
(SHOAIBA Mechanical Workshop) for technical
information support and supplies of materials for
testing.
57.
Finally, I would like to
thank all my family and
friends who have
supported me along the
way.
