Machining of CFRP Composites

2
Alexandria University
Faculty of Engineering
Production Engineering
Department
4th Year
B.Sc. Graduation Project
2019

ABSTRACT
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Composite materials have increased applications in many industries because of their
excellent mechanical characteristics, such as strength-to-weight, stiffness-to-weight,
corrosion resistance, fatigue and thermal expansion compared with metals. Carbon fiber
reinforced polymer (CFRP) composite materials, among other fiber reinforced materials,
have been increasingly replacing conventional materials with their excellent strength
and low specific weight properties.
The presentation first discusses machinability of CFRP under traditional and
nontraditional machining processes, then focuses on drilling and abrasive water jet
machining processes.
In drilling process different of twist drills have been used, in order to examine the ability
of high speed steel and explore carbide twist drill in drilling CFRP.
Abrasive water jet cutting process considered one of the most efficient cutting process
done on CFRP, Slotting experiment has been done using AWJM and Analysis of variance
(ANOVA) has been used to study and analyze the data of these experiment.

5
Composite Materials
• A composite material is a no uniform solid
consisting of two or more different materials
that are mechanically, or metallurgic ally
bonded together. Each of the various
components retains its identity in the
composite and maintains its characteristic
structure and properties.
• Many composite materials are composed of
just two phases; one is termed the Matrix,
which is continuous and surrounds the other
phase, often called the dispersed Phase. The
properties of composites are a function of the
properties of the constituent Phases, their
relative amounts, and the geometry of the
dispersed phase.

CLASSIFICATIONOF COMPOSITE MATERIALS
6

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Fiber-Reinforced
Composites
• Technologically, the most important
composites are those in which the
dispersed phase is in the form of a fiber.
Design goals of fiber-reinforced
composites often include high strength
and/or stiffness on a weight basis.
• Fiber-reinforced composites with
exceptionally high specific strengths and
moduli have been produced that utilize
low-density fiber and matrix materials.
• Fiber-reinforced composites are
subclassified by fiber length. For short
fiber, the fibers are too short to produce
a significant improvement in strength.

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THE MATRIX PHASE
The matrix phase of fibrous composites may
be a metal, polymer, or ceramic.
For fiber-reinforced composites, the matrix
phase serves several functions.
First, it binds the fibers together and acts as
the medium by which an externally applied
stress is transmitted and distributed to the
fibers.
The second function of the matrix is to
protect the individual fibers from surface
damage as a result of mechanical abrasion or
chemical reactions with the environment.
Finally, the matrix prevents the propagation
of brittle cracks from fiber to fiber; the matrix
phase serves as a barrier to crack
propagation.

CFRP Composite
CFRP composite is basically a combination of
polymer matrix reinforced with carbon fibers
with a certain aspect ratio designed to carry
sufficient loads in appropriate application
domain.

CFRP Composite
Properties and Characteristics of CFRP
Composite
1-These materials have been excellent strength
and low specific weight properties.
2- It has also customized strength properties,
3- It has high fatigue, toughness.
4-These materials do not contract/expand due to
change in temperature.
5-These materials do not corrode non-
flammable, behave as chemically resistant, and
exhibit good insulating capability renders these
materials an excellent choice in engineering
application.

APPLICATIONSOF CFRP COMPOSITE
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AEROSPACE ENGINEERING
SPORTS GOODS

OTHER APPLICATIONS
• Civil engineering
• Musical instruments, including violin bows,
guitar picks and pick guards
• High-performance drone bodies and other
radio-controlled vehicle
• Dentistry, carbon fiber posts are used in
restoring root canal treated teeth.
• Railed train bogies for passenger service.
• Laptop shells and other high-performance
cases.
• Carbon woven fabrics.

CHAPTER 2
MACHINING OF
CFRP COMPOSITE
MACHINING OF CFRP COMPOSITE20
MACHINING OF CFRP COMPOSITE20

14
INTRODUCTION
Machining of CFRPs is often difficult due
to the anisotropic and inhomogeneous
material properties

15
INFLUENCING FACTORSTOTHE MECHANICAL
PROPERTIES OF FRPS
The machinability of FRPs is
mainly influenced by the
mechanical properties of the FRP
which is determined by the factors
• We should consider these
parameters to avoid damages
which could happened to
composite material.
• Burrs, delamination, and
interlaminar cracks most regular
defects of CFRP

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Turning process
Fiber type, orientation, and volume
fraction are material properties that
influence machinability.
The tool materials suitable for turning
FRP’s are those which possess:
high hardness
like cemented carbides, cubic boron
nitride (CBN), and polycrystalline
diamond (PCD).
TRADITIONAL MACHINING PROCESSES OF CFRP

MILLING PROCESS
Milling is one of the most frequently used
material removal processes in manufacturing
parts made of FRPs. In milling, as opposed to
turning, the cutting tool is rotating and quite
often more than one cutting edge is engaged in
cutting at the same time.
This adds complexity to the milling process in
terms of fiber orientation, chip size, and
cutting forces that continuously vary with tool
rotation.
Machinability of FRPs in milling is characterized
by tool wear, surface roughness, and
delamination

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Surface Grinding Process
Used to produce intricate shapes and
functional surfaces with good surface
quality and desired tolerances, which are
as the finishing process for CFRP
composites
one of the leading methods for machining
CFRP composites.
traditional grinding make too many
problems.
TRADITIONAL MACHINING PROCESSES OF CFRP

DRILLING PROCESS
Drilling is an essential processing method in the
assembly and connection of CFRP components.
The inhomogeneity and anisotropy of FRP
composites coupled with the abrasive nature of
the reinforcement fibers and complexity of
cutting tool geometry make quality hole
production challenging, largely due to process
induced damages and defects while drilling.
Drills with different point angles (155°, 175° and
185°) have been used to study the influence of
the point angle on delamination; the results
show that delamination benefits from smaller
point angles

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AWJ process uses erosive effect of high velocity water jet mixed with abrasive to remove
work piece material.
There are parameters of (AWJM) process that can influence the performance, efficiency
and effectiveness of machining process:
• Abrasive type
• Abrasive grain size
• Water jet pressure
• Stand of distance
• traverse speed
NON-TRADITIONAL MACHINING PROCESSES OF CFRP
ABRASIVEWATER JET PROCESS

• An inappropriate selection of the cutting
velocity may produce surface roughness
values and kerf taper angles out of
normal. It may also cause the burr, which
would require secondary finishing.
• The short life of some parts, like nozzle
and orifice, adds replacement costs and
overheads to abrasive water jet
machining.
• High cost, noise
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ADVANTAGES OF AWJM
• Extremely versatile process.
• Minimum material waste due to
cutting.
• Less heat effected zone
• Require minimal force during
machining.
DISADVANTAGES OF AWJM

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The machining of lightweight and multilateral components is done by the LBM due to
• its non-contact type forceless operation
• small laser beam diameter at the focus point leads to narrow heat affected zone;
• very complex 2-D profiles can be cut without much difficulty.
This process produces a heat affected zone (HAZ) .The influence of cutting process
parameters on the cut surface quality such as: Laser power variations show less effect
on the kerf width, whereas the cutting speed is a more dominant factor affecting the
HAZ.
LASER BEAM MACHINE

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WATER JET GUIDED
LASER MACHINING
PROCESS
• According to Laser cutting of CFRP
which still has challenges because
of its thermal damage to material
• To solve thermal damage problem
in laser cutting, water jet guided
laser technique which has been
proved to be an effective
technique to reduce heat damage
• The water jet can efficiently expel
the melt from the cut, and cooling
condition of the cut was improved
Thus, the thermal damage of the
sample can be avoided

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ELECTRICAL DISCHARGE
MACHINING PROCESS
They concluded that the EDM process has the
capability of producing irregular shaped holes
with good surface finish and dimensional
accuracy when machining CFRP.
CFRP is electrically conductive material, but the
bonding material (fibers) is non-conductive
material. The non-conductive fibers does not
affect the machining efficiency because in the
EDM process, work piece and tool must be good
electrically conductive materials.
some results from the investigations described
under the consideration

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The machining process of the CFRP materials by
EDM using copper or graphite electrodes is more
feasible than other machining processes.
• Experimental results confirm that the
material removal rate increases with pulse-on
time, pulse.
• The material removal rate with machining
using graphite electrode is relatively higher
than that when using copper electrode.
ELECTRICAL DISCHARGE
MACHINING PROCESS

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ROTARY ULTRASONIC
MACHINING
RUM is a hybrid nontraditional machining
process that merges the material removal
mechanisms of conventional diamond
grinding and static USM, resulting in
higher MRR than that attained by either
diamond grinding or USM.
In this process, a rotary core drill over
which the diamond abrasives are
impregnated is ultrasonically vibrated and
continuously fed toward the work piece.
Coolant is continuously pumped through
the core of the drill, which washes away
the swarf, prevents overheating and make
the machining zone cool.

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ROTARY ULTRASONIC
MACHINING
This process makes the machinability of
a work material quite independent of its
other properties, i.e., chemical reactivity
and electrical conductivity. The RUM
process is also considered a nonthermal,
nonchemical and nonelectrical
machining method.
Accuracy of the machined hole has
Higher precision of holes was observed
during RUM of CFRP composites.

CHAPTER 3
EXPERIMENTS
ON DRILLING OF
CFRP COMPOSITE

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MACHINE SPECIFICATIONS
The drilling experiments are carried out using
Conventional upright Drilling Machine with high
speed steel (HSS) and Carbide drills
Cutting Speed
(rev/min)
71, 112, 180, 210, 280, 450, 710,
1120, 1800, 2800
Feed rate
(mm/min)
0.08, 0.12, 0.20, 0.32
Motor Power
(HP)
1.5
Spindle Travel
(mm)
200

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WORKPIECE FIXATION
The CFRP workpiece with
dimensions (24 X 26) cm, was
fixed using two nuts, two screws
and two plates of wood were used
to rise the workpiece from the
table surface to allow the drilling
process

The usage of carbide tool was just
exploratory, to know the capability of
tools made of carbide to drill CFRP, One
tool of carbide with diameter about
6.00 mm and three flutes is used in the
experiment
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CARBIDE TOOL

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THE CONDITIONSOF
CUTTING ARE
Quantity of
holes
Speed (rev/min) Feed rate
(mm/min)
10 450 0.08
4 710 0.08
4 1120 0.08

The experiment of drilling the CFRP has
done with the use of two type of drills
HSS and Carbide
Three identical tools of high speed
steel, each one has two flutes and 6.00
mm diameter.
Each one is used to make four holes
with specified cutting speed and the
drilling process has done with the same
feed rate.
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HSS TOOL

35
THE CONDITIONSOF
CUTTING
Tool Speed
(rev/min)
Feed
rate(mm/min)
1 112 0.08
2 180 0.08
3 450 0.08

WEARINGTESTS
Using Tool Maker Microscope,
the tool wear of the three HSS
tools and the Carbide tool,
can be measured the
microscope has two
micrometers in x and y
directions, both has range
limits from 0.00 to 100.00 mm
and scale value about 0.01
mm, The tools were fixed by
using three jaw vice

THETOOLWEAR RESULT
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Number
of hole
Drilling
Time
(min)
Wear1(
mm)
Wear2
(mm)
Wear3
(mm)
Average
(mm)
1 15 0.03 0.04 0.05 0.04
2 27 0.04 0.03 0.05 0.04
3 26 0.04 0.04 0.05 0.043
4 25 0.07 0.04 0.06 0.056
5 36 0.13 0.07 0.09 0.093
6 37 0.05 0.08 0.11 0.08
7 37 0.06 0.05 0.07 0.06
8 25 0.04 0.05 0.05 0.043
9 27 0.05 0.06 0.09 0.066
10 26 0.06 0.07 0.05 0.06
Number
of holes
Drilling
Time
(min)
Wear1
(mm)
Wear2
(mm)
Wear3
(mm)
Averag
e (mm)
1 19 0.05 0.05 0.05 0.05
2 19 0.07 0.06 0.05 0.06
3 21 0.06 0.07 0.05 0.06
4 18 0.07 0.07 0.05 0.063
Number
of holes
Drilling
Time
(min)
Wear1
(mm)
Wear2
(mm)
Wear3
(mm)
Averag
e (mm)
1 14 0.07 0.07 0.01 0.05
2 13 0.17 0.16 0.14 0.156
3 13 0.17 0.12 0.14 0.143
4 13 0.05 0.07 0.14 0.086

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THE CARBIDETOOLATTHE END OF DRILLING
EXPERIMENTS
Carbide tool after cutting process, wear increase with increasing speed
The smallest wear = .05 mm
The largest wear = 0.15 mm

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THETOOLWEAR RESULTS
FROMTHETHREE HSS
TOOLSAND DRILLING
TIME
The First HSS Tool Wear after Drilling with
112 (rev/min)
Hole
Number
Drilling
Time
(sec)
Wear 1
(mm)
Wear 2
(mm)
Average
(mm)
1 25 0.17 0.18 0.175
2 31 0.43 0.23 0.33
3 27 0.20 0.24 0.22
4 29 0.10 0.30 0.20

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THE SECOND HSSTOOL
WEAR AFTER DRILLING
WITH 180 (REV/MIN)
Hole
Number
Drilling
Time
(sec)
Wear 1
(mm)
Wear 2
(mm)
Average
(mm)
1 18 0.20 0.19 0.195
2 20 0.27 0.32 0.295
3 21 0.24 0.32 0.28
4 21 0.37 0.40 0.385

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THETHIRD HSSTOOL
WEAR AFTER DRILLING
WITH 450 (REV/MIN)
Hole
Numbe
r
Drilling
Time
(sec)
Wear 1
(mm)
Wear 2
(mm)
Averag
e (mm)
1 9 0.52 0.62 0.57
2 11 0.24 0.33 0.285
3 10 0.40 0.38 0.39
4 8 0.46 0.40 0.43

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TAYLOR RELATION
The tool life is the time a newly
sharpened tool cuts satisfactorily before
it becomes necessary to remove it by
regrinding or replacement.
The tool life is the most widely used
criterion for the evaluation of the
machinability of the different materials
because of its direct impact on the total
machining cost.
Max allowable wear is equal to 0.2 mm,
𝑣1< 𝑣2< 𝑣3 , T1>T2>T3
𝑣1
𝑣2
𝑣3
0
0.1
0.2
0.3
0.4
0.5
0.6
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55
WEAR(MM)
TIME (MINUTE)
Tool wear
Tool 1 Tool 2 Tool 3

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TAYLOR RELATION
Tools velocity(m/mi
n)
Time for
reaching
allowable wear
(min)
1 2.1 0.44
2 3.4 0.31
3 8.5 0.06
V1; T1
V2; T2
V3; T3
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0 2 4 6 8 10
Time(min)
Velocity(m/min)
Tool life&Velocity Relation

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TAYLOR RELATION
𝑇 = 𝐶𝑣 𝑣 𝑘
where υ is the cutting speed in
m/min, T is the tool life in min, 𝐶𝑣 is
the constant equal to T for 𝑣 = 1
m/min and k is the negative slope of
the straight line and equal in
magnitude to the inverse of the
exponent n.
k = tan 𝛼 =
𝑎
𝑏
=
1
𝑛
From Taylor relation
The Slope of line = k =
𝑎
𝑏
= -1.473
𝐶𝑣 = 1.514 min
y = 1.5137x-1.473
0.01
0.1
1
10
0.01 0.1 1 10
LogT
Log V
Taylor Relation
𝐶_𝑣

46
OVERSIZE
The process accuracy is measured
through the overcut (oversize)
produced during drilling of holes,
one of factors affect accuracy of
machined parts is tool wear. The
hole oversize measures the
difference between the hole
diameter, measured at the top
surface, and the tool diameter
Tool Tool
Diameter
Average
Hole
Diameter
Oversize
Carbide 6.00 mm 6.1585 mm 0.1585 mm
First HSS 6.00 mm 6.185 mm 0.185 mm
Second
HSS
6.00 mm 6.2875 mm 0.2875 mm
Third HSS 6.00 mm 6.27 mm 0.27 mm

CHAPTER 4
EXPERIMENT ON
AWJM OF CFRP
COMPOSITE

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AWJ MACHINE
SPECIFICATION
A flow 3-axis CNC abrasive water jet
machine pump capable of delivering
pressure up (380 MPa)
Abrasive flow rate is equal to 3 g/s,
orifice material/diameter is equal to
0.30 mm.
Focusing tube diameter/length is
equal to 1.02 mm.
jet impact angle is equal to 90⁰.
Linear slots of 30 mm width were cut
in CFRP laminate having 10.4 mm
thickness.

EXPERIMENT PLAN
49
Changing feed
• The feed speed
values have been
changed from 50 to
300mm/min with
fixed other
parameters, the
standoff distance
2mm, and pressure
350MPa, the total
slots done are 12
slots, the experiments
have been done twice
to increase accuracy
of the results.
Repeatability
• Repeatability test
has been done with
theoretical optimum
conditions from our
point of view which is
100 mm/min feed
2mm standoff
distance, 350 MPa
Pressure, the total
slots have been cut
are six slots. As a total
number slots done at
the same condition it
is equal to 10 slots.
Test Matrix
• Test matrix is a
group of experiment
with different
conditions to study
the effect of changing
feed, SOD, and
pressure. The feed
was varying between
50 and 100mm/min
and pressure varies
between 100 and
350MPa, the total
slots have been cut
are eight slots. The
first four slots have
been cut by 2mm SOD
and last four slots
have been cut by
4mm SOD.
Changing SOD
• The two final slots
have been with
changing the SOD
8mm and 12 mm with
constant pressure
350MPa.

50
Design of Gauge
There is a gauge used in experiment
to control stand of distance of
nozzle. The dimensions of gauge is
2, 4 and 8 mm.

52
Shows the workpiece after cutting process
EXPERIMENT RESULT

53
KERF FORM
ANALYSIS
Kerf geometry is a characteristic of
major interest in abrasive water jet
cutting. It has a wider entry and its
width decrease as the jet cut into
the material, by this kerf is
produced.
Kerf taper is defined as a half of the
kerf width variation per millimeter
of depth of cut (or penetration).
Kerf taper =
𝑊𝑡− 𝑊 𝑏
2𝑡

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JET DEVIATION
FACTOR JDF
Jet deviation factor is the ratio
between actual slot area and
theoretical slot area.
This deviation happened due to the
form of AWJ flow of water and
abrasives together, during the
entrance of water from nozzle the
high diffusion is occurred, and with
the friction between surface of the
part and the shape of water jet
become more focused, Causing the
middle angle.

55
JET DEVIATION
FACTOR JDF
Area actual has been calculated
using AutoCAD software, while the
theoretical area calculated
according to equation 2, where t is
the workpiece thickness and W is
the expected slot width, it is equal
to 10.608 𝑚𝑚2
Theoretical area = t*W

56
JET DEVIATION
FACTOR JDF
Jet deviation factor was calculated
according to equation 3 where 𝐴 𝑎 is
the actual area, and 𝐴 𝑡ℎ is the
theoretical area. Jet deviation factor
(JDF) is equal to
JDF =
𝐴 𝑎
𝐴 𝑡ℎ

57
EXPERIMENT RESULT
Slit no. Parameters Responses
SOD (mm) Pressure
(MPa)
Feed
(mm/min)
Top Angle Middle
Angle
Top Width
(mm)
Bottom
Width
(mm)
Area
(mm2)
VRR
(mm3/min
)
Calculated
angle
Jet
deviation
factor
Change
Feed
1 2 350 50 5.76 2.02 1.45 0.98 11.6689 583.445 3.16 1.1
2 2 350 100 3.82 1.48 1.57 1.21 13.3403 1334.03 2.44 1.26
3 2 350 150 6.08 1.1 1.52 1.08 12.7902 1918.53 3 1.21
4 2 350 200 4.11 3.96 1.5 0.94 11.9429 2388.58 3.76 1.13
5 2 350 250 5.11 2.58 1.42 0.93 11.0264 2756.6 3.32 1.04
6 2 350 300 5.69 1.79 1.34 0.86 9.7437 2923.11 3.25 0.92
7 2 350 50 2.29 1.64 1.65 1.44 15.558 777.9 1.44 1.47
8 2 350 100 3.2 1.66 1.53 1.2 14.1675 1416.75 2.23 1.34
9 2 350 150 3.8 2.39 1.47 1.02 12.2017 1830.255 3.04 1.15
10 2 350 200 5.29 1.65 1.49 1 12.4459 2489.18 3.3 1.17
11 2 350 250 5.25 2.13 1.43 0.96 11.2646 2816.15 3.16 1.06
12 2 350 300 7.12 1.83 1.37 0.87 10.4099 3122.97 3.37 0.98
Repeatability
13 2 350 100 4.48 1.65 1.46 1.18 11.7454 1174.54 1.86 1.11
14 2 350 100 3.99 2.09 1.5 1.12 12.6312 1263.12 2.55 1.19
15 2 350 100 4.55 1.93 1.53 1.17 12.8207 1282.07 2.41 1.21
16 2 350 100 4.48 0.82 1.51 1.12 13.2345 1323.45 2.65 1.25
17 2 350 100 3.91 1.11 1.52 1.2 11.4979 1149.79 2.14 1.08
18 2 350 100 3.82 1.51 1.49 1.2 13.8957 1389.57 1.95 1.31

58
EXPERIMENT RESULT
Slit no. Parameters Responses
SOD (mm) Pressure
(Mpa)
Feed
(mm/min)
Top Angle Middle
Angle
Top Width
(mm)
Bottom
Width
(mm)
Area
(mm2)
VRR
(mm3/min
)
Calculated
angle
Jet
deviation
factor
Test
Matrix
19 2 100 50 5 2.3 1.52 1.02 13.0889 654.45 3.32 1.23
20 2 100 100 9.15 2.73 1.44 0.83 10.5015 1050.15 4.11 0.99
21 2 350 50 2.75 1.56 1.6 1.36 15.2793 763.97 1.58 1.44
22 2 350 100 2.45 1.43 1.5 1.19 13.2966 1329.66 2.11 1.25
23 4 100 50 7.6 1.86 1.72 1.1 13.3425 667.13 4.18 1.26
24 4 100 100 8.69 1.24 1.53 1.11 10.4201 1042.01 2.85 0.98
25 4 350 50 7.69 2.06 1.97 1.46 16.8738 843.69 3.43 1.59
26 4 350 100 7.26 2.67 1.82 1.28 14.6702 1467.02 3.58 1.38
27 2 100 50 7.54 2.23 1.45 0.98 11.0585 552.93 3.17 1.04
28 2 100 100 8.48 1.91 1.38 0.83 9.881 988.1 3.71 0.93
29 2 350 50 3.35 0.97 1.62 1.38 15.0592 752.96 1.63 1.42
30 2 350 100 2.46 1.54 1.51 1.23 13.1559 1315.59 1.88 1.24
31 4 100 50 7.13 1.27 1.7 1.05 12.8483 642.42 4.39 1.21
32 4 100 100 10.26 1.24 1.59 1.11 11.4753 1147.53 3.27 1.08
33 4 350 50 4.47 2.11 1.93 1.59 16.79 839.5 2.28 1.58
34 4 350 100 7.96 2.15 1.85 1.26 16.148 1614.8 3.97 1.52
SOD
Change
35 8 350 100 10.11 2.29 2.17 1.51 17.7512 1775.12 4.48 1.67
36 8 350 100 8.82 2.2 2.21 1.52 17.5817 1758.17 4.67 1.66
37 12 350 100 18.23 2.4 2.78 1.63 20.0947 2009.47 7.77 1.89
38 12 350 100 16.56 3.56 3.02 1.77 22.5104 2251.04 8.44 2.12

ANOVA
• Analysis of variance (ANOVA) is a
statistical tool used to compare
three or more means.
• “It is devoted to the study of the
variability of factors influencing
experimental observations,
involving simple (one- and two-
factor), and complex (multiple-
factor) experiments and designs”.
59

ANOVA
• All populations involved follow a
normal distribution.
• All populations have the same
variance.
• The samples are randomly
selected and independent of one
another.
• If ANOVA assumes the
populations involved follow a
normal distribution.
60
Assumptions required applying
ANOVA

DATA ANALYSIS
The analysis represented the effect
of changing the parameters on two
of the most important features, slot
area and top angle
61

DATA ANALYSIS
ACCORDING TO THE AREA OF SLOT

63
CUBIC PLOT FOR AREA
Each corner of the Cube plot shows
a different value of area at different
value of pressure, SOD, and feed
speed shown in Figure 4.8. At
minimum working condition
Pressure = 100 MPa, SOD = 2, and
Feed Speed = 50 mm/min area is
equal to 12.0737 𝑚𝑚2
; while at
maximum working condition
Pressure = 350 MPa, SOD = 4 mm,
and Feed Speed = 100 mm/min area
is equal to15.4091 𝑚𝑚2
, and so
on…
Effect of Pressure, SOD and Feed speed on the slot Area

64
INTERSECTION PLOT
Interaction effects represent the
combined effects of factors on the
dependent measure.
The slop of SOD with Feed Speed is
parallel, it means the two parameters
don't affect each other, as well as the
Pressure with Feed Speed.
The slop of SOD with Pressure is not
quite parallel, it means the interaction
effect will be significant, given enough
statistical power and more
experiment data.

65
PARETO CHART
Represented the effect of pressure,
SOD and feed speed on slot area,
from the plot the pressure has the
most significant effect on the
process

66
MAIN EFFECT PLOT FOR AREA
With SOD increase the mean area
also increase, due to the shape of
the water jet, as well as with
pressure increases. While the feed
speed increases the mean area
decreases.

67
Contour Plot shows the relationship between a fitted response and two continuous variables. The
range of areas in these experiments is from 12 to 16.

68
SURFACE PLOT FOR AREA
Surface plot is a 3D plot shown the
effect of pressure and SOD on the
area at the same time

DATA ANALYSIS
ACCORDING TO THE TOP ANGLE

70
CUBE PLOT
Each corner of the Cube plot shows
a different value of area at different
value of pressure, SOD, and feed
speed shown in Figure 4.14. At
minimum working condition
Pressure = 100MPa, SOD = 2 mm,
and Feed Speed = 50 mm/min top
angle is equal to 2.455°; while at
maximum working condition
Pressure = 350, SOD = 4, and Feed
Speed = 100 mm/min top angle is
equal to 7.610° and so on…
Effect of Pressure, SOD and Feed speed on the top angle

71
INTERSECTION PLOT
The slop of SOD with Feed Speed is
nearly parallel, it means the two
parameters don't affect each other.
While the Pressure with Feed Speed
is not quite parallel, the two lines
will intersect if there are more
experiment data, it means the
interaction effect will be significant,
as well as the slop of SOD with
Pressure

72
PARETO CHART
Represented the effect of pressure,
depth of cut and feed speed on slot
area, from the plot the pressure has
the most significant effect on the
process, followed by the SOD, and
the combined effect of theme
together.

73
MAIN EFFECT PLOT FOR
TOP ANGLE
With SOD increase the top also
increase, due to the shape of the
water jet, as well as with feed speed
increases. While with pressure
increases the top angle decreases.

74
The contour plot for the effect of pressure
and SOD together on top angle for different
values
The contour plot for the effect of pressure
and feed speed together on top angle for
different values

75
Surface plot is a 3D plot shown the
effect of pressure and SOD on the
top angle at the same time

DATA ANALYSIS
EFFECT OF TRAVERSE SPEED

77
With increasing of feed speed the
area decrease, so in order to
minimize the division of the slot
area we need to maximize the feed
speed.
Effect of Traverse Feed on slot area

78
Effect ofTraverse Feed on top and bottom width
With increasing of feed speed the division of top and bottom width decrease, So, in order to
decrees the deviation of top and bottom width we should increase the feed speed

79
Effect of feed speed on top and middle angle
With increasing of feed speed the division of top and bottom width increase, So, in order to
decrease the deviation of top and bottom width we should decrease the feed speed.

81
EFFECT OF DRILLING
PROCESS
Since composites are neither
homogeneous nor isotropic, drilling
raises specific problems that can be
related to subsequent damage in
the region around the holes.
The experiment of drilling CFRP
results in high tool wear and
material failures, such as matrix
cracking, layers separation, swelling
and delamination occurred in
workpiece.

82
EFFECT OF DRILLING
PROCESS
high speed steel (HSS) suffers
extreme wear and should not be
used for composites removal,
Tungsten carbide (WC) and PCD
tooling instead can provide a good
compromise between tool life and
production costs.
A coated layer on the surface of drill
bits leads to longer drill life than is
obtained with typical uncoated drill
bits.

83
Data analysis using ANOVA represented the
effect of changing of different parameters
such as pressure, SOD, and feed speed on
two of the most important features, slot area
and top angle:
• The optimum condition according to slot area
analysis is minimum SOD and pressure where
P = 100 MPa, and max feed speed = 300
mm/min, and SOD = 2 mm.
• Optimum condition according to slot top angle
is minimum SOD and feed speed where feed
maximum pressure = 350 MPa, min speed =
50 mm/min, and, SOD = 2 mm.
• In order to decrease Kerf taper the optimum
working conditions is max pressure = 350
MPa, and feed speed = 50 mm/min,
minimum SOD = 2 mm.
EFFECT OF AWJM
PROCESS

84
JET DEVIATION
FACTOR JDF
JDF was supposed to be more than
one because the actual area is
larger than the theoretical area, due
to the jet water dispersion, but with
using of high feed speed the water
jet caused Incomplete slot cutting
as shown in slot number 6,12, and
28 so the JDF become less than one.

86
RECOMMENDATIONS
Error Photo Cause Recommendation
Uncut layers Drilling with HSS twist
drill
Tungsten carbide (WC) and
PCD tooling instead can
provide a good compromise
between tool life and
production costs.
Delamination Wearing of HSS tool
during drilling process

87
RECOMMENDATIONS
Fixation Due to using non suitable
fixation method
After each process make
sure the workpiece is still
perpendicular with the AWJ
nozzle.
Non through slot Due to low cutting
pressure with high feed
speed
Increase the pressure or
feed speed.
In order to increase the
accuracy increasing both is
recommended.

88
RECOMMENDATIONS
Large top angle Increasing of SOD and
feed speed, due to the
shape of water jet during
cutting process
Decreasing of SOD, and feed
speed, increase pressure.
Large area Increasing of SOD and
pressure increase
Decrease SOD and speed
feed, Increase the pressure.

90
FUTUREWORK
Based on the results presented within this
book, this section gives an outlook of
possibilities for future work.
• Cutting strategy research has been focused on hard
materials that are too difficult to machine so, it be
necessary to study the surface roughness of the holes
and slots.
• Due to Composites suffering from several different
types of damage due to the machining process
including; fiber pull-out, inter-ply delamination, matrix
cracking, matrix burning, uncut fibers and fiber-matrix
de-bonding measuring surface roughness is important.
• Measuring Surface roughness and damage
characterization of composite materials are necessary
after machining in order to assess surface quality.
• Accurate and reliable surface roughness measurement
of composite materials can be challenging because of
the non-homogeneous structure of composites and the
variation in damage.
• Important issue is whether the surface roughness
parameter (Ra) alone can give an accurate
representation of the damage from machining or do
other surface roughness parameters such as maximum
peak to valley height (Rt), Skewness (Rsk) and Kurtosis
(Rku) also need to be considered.

TEAM
DENA MOHAMAD SABER SOUAD MABROK SALLAM MENNATULLAH AHMED HADEER ATEF RAGAB
91
YOUSSRA SHAABN MAHMOUD
Supervised by Prof.Dr. Helmi A. Youssef

Machining of CFRP Composites

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