Drilling of TiO<sub>2</sub> and Zns Filled Gfrp Composites

Paper Menu >>

Journal Menu >>

Journal of Minerals and Materials Characterization and Engineering, 2012, 11, 785-789

Published Online August 2012 (http://www.SciRP.org/journal/jmmce)

Drilling of TiO2 and ZnS Filled GFRP Composites

K. V. Arun1*, D. Sujay Kumar2, M. C. Murugesh3

1Department of Mechanical Engineering, Government Engineering College, Haveri, India

2Department of Studies in Industrial and Production Engineering, University B.D.T. College of Engineering, Davangere, India

3Department of Mechanical Engineering, Gowdara Mallikarjunappa Institute of Technology, Davangere, India

Email: *[email protected]

Received March 13, 2012; revised April 30, 2012; accepted May 21, 2012

ABSTRACT

In the present work an attempt has been made in order to investigate the drilling behavior of the TiO2 and ZnS filled

glass fabric reinforced polymer matrix composites (GFRP). Th e volume fractions in the matrix were chosen as 1%, 2%

and 3%. Drilling has been con ducted on a rad ial drilling machin e. Speed of drilling and drill tool d iameter were consid-

ered as the varying parameters with three levels. Thrust force has been considered as the output parameter and is been

measured in each combination of parameters chosen. Results reveal that, the addition of filler will increase the thrust

force developed during drilling, also results indicate that, addition of filler will increase thrust force upto 2 vol% of

filler thereafter increase in filler content result in almost constant thrust developed. Also it can be observed that, with

the increase in drill tool diameter the thrust developed also in creases.

Keywords: Fillers; Thrust Force; Drilling; GFRP; Speed

1. Introduction

Polymer matrix composites are increasingly being used

because of their high stiffness, specific strength and wear

resistance. On account of their good combinations of

properties, fiber reinforced polymer composites are used

particularly in the automotive, aircraft industries and the

manufacture of spaceships and sea vehicles [1]. It is gen-

erally known that the epoxy resins with appropriate cur-

ing agents find use as products in protective coatings,

adhesives, structural components because of their good

mechanical properties, excellent chemical resistance,

good wettability and electrical characteristics [2]. Their

use is always indicated where fluids are ineffective or

cannot be tolerated because of the possibility of con-

tamination of the product or the environment, or the lack

of opportunity for maintenance [3].

Many researchers [4-7] were reported that the wear

behavior of polymers was improved by the incorporation

solid particles. The filler materials include organic, inor-

ganic and mechanical particulate materials. The addition

of filler particles to polymer matrices can produce a

number of desirable effects, and this has been widely

been investigated in the past decades. Among polymers,

epoxy resin is widely used in production of glass fiber

composites due to their wetting power and adhesion to

glass fiber, low setting shrinkage, considerable cohesion

strength, adequate dielectric characteristics, and thermal

properties. Epoxies commonly modified by the inclusion

of inorganic-particulate fillers, such as silica, alumina,

mica or talc. Fillers are added to improv e fracture tough-

ness and electrical or heat transfer properties, to increase

resin stiffness, wear resistance, and to reduce the coeffi-

cient of thermal expansion [8].

Drilling of composite materials irresp ective of the area

of application can be considered as a critical operation

owing to their tendency to delaminate when subjected to

mechanical stresses. With regard to the quality of ma-

chined component, the principal drawbacks are related to

surface delamination, fibre/resin pullout and inadequate

surface roughness of the hole wall. Among the defects

caused by drilling, delamination appears to be the most

critical. In order to overcome these difficulties it is nec-

essary to develop procedur es to select appropriate cutting

parameters, due to the fact that an unsuitable choice

could lead to unacceptable work material degradation.

The variation of cutting forces with or without onset

damage during drilling was investigated [9] and con-

cluded that a damage-free drilling process may be ob-

tained by the proper selections of tool geometry and cut-

ting parameters. The influence of trepanning tool on

thrust force and torque when drilling GFRP has been

investigated [10]. The investigation showed that the per-

formance of the trepanning tool was superior to the con-

ventional twist drill, resulting in 50 and 10% of thrust

force and torque, respectively. In order to investigate the

effect of the drill diameter on the thrust force and torqu e,

*Corresponding author.

K. V. ARUN ET AL.

786

researchers [11] employed conventional high speed twist

drills with diameters of 8, 9, 10, 11, 12, and 13 mm to

machine a glass fibre reinforced plastic using a constant

rotational speed of 875 rpm and feed rates of 0.1 - 0.23

and 0.5 mm/rev. The results indicated that thrust force

and torque increased with drill diameter and feed rate,

due to the increase in the shear area. Increasing cutting

speed also resulted in higher thrust force and torque,

however, not to th e same extent as when feed rate is ele-

vated. Effect of drill size and feed on thrust force and

torque has been investigated [12].

From the review of previous works carried out it is

clear that, addition of filler material will improve the

wear properties of the glass fabric reinforced composites

(GFRP). Since large structures of composites cannot be

made out of single mould, composites need to be fas-

tened. Fastening of composites is done by either adhesive

joining or mechanical fastening. To join composites by

mechanical fastening, composites needs to be drilled.

Also it is known that the speed of drilling and drill tool

diameter effects the hole quality to large extent. The

quality of hole generated and delamination is directly

dependent on the Thrust force developed during the

process of drilling. Hence the present work concentrates

on the evaluation of Thrust force generated during drill-

ing, while the speed of drilling and drill tool diameter are

varied. Thrust force gen erated during drilling of unfilled,

TiO2 filled and ZnS filled composites has been recorded.

2. Materials and Experimentation

2.1. Materials

The matrix material used was a medium viscosity epoxy

resin (LAPOX L-12) and a room temperature curing

polyamine hardener (K-6). This matrix was chosen since

it provides good resistance to alkalis and has good adhe-

sive properties. The reinforcement material employed

was 7-mil E-glass fabric. The Titanium dioxide (TiO2)

amorphous powder and Zinc Sulphide (ZnS) amorphous

powder are used as filler materials.

2.2. Composite Combinations

Hand lay-up technique of laminating the composites has

been employed for composite fabrication. Two material

compositions of Glass/Epoxy (G-E) composites were

chosen namely G-TiO2-E and G-ZnS-E. Each material

composition has been fabricated for three different vol-

ume fractions, the details of the percentage volume frac-

tions of epoxy resign, glass fabric and fillers are shown

in Table 1.

2.3. Experimentation

Large plates of composites are made in order to carryout

drilling operation with 10mm thickness. Drilling has

been carried-out in a radial Drilling Machine. The drill-

ing machine is been connected to a Drill Tool Dyna-

mometer which gives the digital reading. Speed of drill-

ing and Drill tool diameters are chosen as input parame-

ters and Thr ust force is con sidered as the outpu t parame-

ter. During conducting tests the maximum Thrust re-

corded is considered as the resultant, and has been re-

corded. The summary of parameters considered for drill-

ing is shown in Table 2.

3. Results and Discussion

Composites can be joined with the help of fasteners,

preferably mechanical fastening, and to do so, it is nec-

essary to drill holes on the composite plates. Hence in the

present work drilling is considered as the machining op-

eration and carried-out on filled and unfilled composites.

Drilling holes in composites can cause failures that are

different from those encountered when drilling metals.

Delamination, fracture, break-out and separation are

some of the most common failures. Delamination (sur-

face and internal) is the major concern during drilling

composite laminates as it reduces the structu ral integrity,

results in poor assembly tolerance, adds a potential for

long term performance deterioration and may occur at

both the entrance and exit plane. Delamination can be

Table 1. Composite combinations.

Sl. No.FillerCombination or volume fractions Representation

01 - Glass Fabric 60% + E poxy 40% GE

02 Glass Fabric 60% + TiO2 1%

+ Epoxy 39% GTE-I

03 Glass Fabric 60% + TiO2 2%

+ Epoxy 38% GTE-II

TiO2

Glass Fabric 60% + TiO2 3%

+ Epoxy 37% GTE-III

05 Glass Fabric 60% + ZnS 1%

+ Epoxy 39% GZE-I

06 Glass Fabric 60% + ZnS 2%

+ Epoxy 38% GZE-II

ZnS

Glass Fabric 60% + ZnS 3%

+ Epoxy 37% GZE-III

Table 2. Summary of parameters considered for drilling.

Sl. No. Speed in rpm Drill diameter in mm

01 525 3

02 951 6

03 1625 9

K. V. ARUN ET AL. 787

overcome by finding optimal thrust force (minimum

force above which delamination is initiated). Figure 1

shows push out delamination at exit because at a certain

point loading exceeds the interlaminar bond strength and

delamination occurs. Figure 2 shows peel-up delamina-

tion at the entrance, because the drill first abraded the

laminate and then pulled the abraded material away

along the flute causing the material to spiral up before

being machined completely. This type of delamination

decreases as the drilling proceeds since the thickness

resisting the lamina bending becom es greater.

In order to know the effect of filler volume on the

drilling behavior and influence on thrust force the speci-

men are drilled for three different drill sizes and for three

different spindle speeds.

3.1. Effect of Process Parameters on the Drilled

Composite and the Drilling Performance

In order to know the effect of drill size and drilling speed

on the drilling performance, each combination of the

composites is drilled for different drill diameters and

drilling speeds. When speed is varied drill size is kept

constant and in the same way speed is kept constant

when drill size has varied.

Figure 1. Push-out delamination at exit.

Peeling

Action

Figure 2. Peel-in delamina tion at entran ce.

During drilling, a vertical force, that is, a thrust force,

is generated. This thrust force can be considered as the

sum of several components, each one rising either from

the cutting process or from the friction between material

and cutting tool. The cutting process occurs along the

cutting lips and at the chisel edge. The cutting process

along the lips generates a force on each lip that has a

force component parallel to the axis of the drill, that is,

the feed direction. Moreover, the chisel edge generates a

vertical penetration force. The friction forces arise from

two components. The first is related to the friction be-

tween the side surface of the tool and the generated hole

surface, which leads to the vertical force. The second

component is related to the friction between the chip

flow along the helical grooves, which generates the ver-

tical force. Sum-up of all this forces gives the total thrust

force acting on the d rill. Th e thru st force ob served du ring

drilling no t only d epend s on th e geometry of the d rill and

on the type of material and laminate be ing worked upon,

but also on the relation ship between the feed rate and the

cutting speed, as well as on the degree of wear of the

drill.

In the present work Thrust force is considered as the

out-put or resultant of drilling. Thrust force is measured

with the help of a calibrated drill-tool d ynamometer. The

thrust force generated is measured in each case and has

been recorded, the results of which are shown in figures

following.

Figures 3-5 show the thrust force against different

drilling speeds with respect for 3 mm, 6 mm and 9 mm

drill sizes respectively for TiO2 filled composites. From

the figures it can be observed that the Thrust generated

increases with the increase in the speed of drilling. The

common thing that can be observed in all the three cases

is that, the drilling speed is more significan t on the thrust

force, as the spindle speed increases the thrust force gen-

erated also increases. This is because of the reason as the

spindle speed increases the resisting force also increases,

after certain limit the effect of speed becomes less sig-

nificant, this can be observed from block for speed-2 and

THRUST FORCE FO R 3m m DRI LL-TiO

Speed-1Speed-2 Speed-3

Speed

Thrust force in Kgf

GTE- I

GTE- II

GTE- III

Figure 3. Comparison of thrust force against drilling speeds

for TiO2 filled composite (3 mm).

K. V. ARUN ET AL.

788

THRUST F O RCE F O R 6 m m DRIL L

Speed-1Speed-2 Speed-3

Spee d

Thr u st for ce in Kgf

-TiO

GTE -I

GTE -II

GTE -III

Figure 4. Comparison of thrust force against drilling speeds

for TiO2 filled composite (6 mm).

THRUST FO RCE FOR 9mm DRIL

Speed-1 Speed-2 Speed-3

Speed

Thrust force in Kgf

L-TiO

GTE-I

GTE-II

GTE- III

Figure 5. Comparison of thrust force against drilling speeds

for TiO2 filled composite (9 mm).

block for Speed-3 in each of the case. The peel-in kind of

delamination can be observed in all the cases, and fiber

pull out is observed at the exit side.

Compared to unfilled and filled composites, thrust de-

veloped during drilling of unfilled composites is com-

paratively lesser with that of filled composites, and wh en

the filler content is under consideration, the effect of

filler content on thrust force is not significan t, this can be

observed from the Figures, in each block the variation in

thrust value is not much differed, this indicates that the

effect of filler is less significant on the drilling perform-

ance. As the drill size varies the thrust force increases

this is because, as the drill diameter increases the force

required by the drill to penetrate the component also in-

creases.

Observations also show that, the Thrust generated in

all the combinations of composites increases with the

increase in drill tool diameter. This is due to reason that,

with the increase in drill tool diameter the shear area

produced by drill too l also in creases, this will leads to th e

increase in Thrust generated.

Figures 6-8 show the thrust force against different

Drilling speeds with respect to 3 mm, 6 mm and 9 mm

drill sizes respectively for ZnS filled composites. From

the figures it is clear that, as the speed of drilling in-

sidering the effect of filler content, the effect of filler

content on the drilling is less significant in case of this

composites, this is because there is no much difference in

thrust force as observed during drilling. As the drill size

increases, the Thrust force required to drill the hole also

increases. The peel-in kind of delamination can be ob-

served in all the cases, and fiber pull out is observed at

the exit side.

As the dri

creases there is an increase in the thrust force also. Con-

lling speed exceeds a certain range, the

Thrust generated remains somewhat constant in all the

cases of composites, this is due to reason that at higher

speeds the heat generated will be more and this heat will

THRUST F ORCE FOR 3 mm DRIL L - ZnS

Speed-1 Speed-2 Speed-3

Spee d

Thrust force in Kgf

GZE- I

GZE- II

GZE- III

Figure 6. Comparison of thrust force against drilling speeds

for ZnS filled composite (3 mm).

THRUST FO RCE FO R 6mm DRI LL-ZnS

Speed-1Speed-2 Speed-3

Speed

Thru st force in Kgf

GZE-I

GZE-II

GZE- III

Figure 7. Comparison of thrust force against drilling speeds

for ZnS filled composite (6 mm).

THRUST F ORCE FOR 9mm DRILL- ZnS

Speed-1Speed-2 Speed-3

Spee d

Thrust force in Kgf

GZE- I

GZE- II

GZE - III

Figure 8. Comparison of thrust force against drilling speeds

for ZnS filled composite (9 mm).

K. V. ARUN ET AL.

789

ntation conducted and observations

REFERENCES

[1] H. Pihtili andn of the Wear Be-

haviour of a Gomposite and

make the material behave softer that the usual case and

hence the resistance offered for drilling becomes lesser,

this will result in development of less Thrust. In com-

parison with TiO2 and ZnS filled composites, TiO2 filled

composites will offer more resistance that ZnS filled

composites. Since the ZnS filled composites are com-

paratively less brittle that TiO2 filled composites, they

behaves bit softer at early stages than TiO2 filled com-

posites, offering less oppositio n for drilling.

4. Conclusions

From the experime

made during testing, following conclusion can be drawn:

 The thrust force generated during drilling of filled

composites mainly depends upon drill diameter and

the speed of drilling in the present case.

 Effect of filler volume on the Thrust generated is

neglizable.

 Thrust force developed during drilling of TiO2 filled

composites is more in comparison with ZnS filled

composites.

N. Tosun, “Investigatio

lass-Fibre-Reinforced C Plain

Polyester Resin,” Composites Science and Technology,

Vol. 62, No. 3, 2002, pp. 367-370.

doi:10.1016/S0266-3538(01)00196-8

[2] Kishore, P. Sampathkumaran, S. See

theya, A. Murali and R. K. Kumar, “tharamu, S. Vyna-

SEM Observations

ology International, Vol. 22, No. 2, 1989, pp. 103-

of the Effects of Velocity and Load on the Sliding Wear

Characteristics of Glass Fabric-Epoxy Composites with

Different Fillers,” Wear, Vol. 237, No. 1, 2000, pp. 20-

27.

[3] E. Santer and H. Czinchos, “Tribology of Polymers,”

Trib

109. doi:10.1016/0301-679X(89)90170-9

[4] J. Bijwe and J. Indumathi, “Influence of Fibers and Solid

. Sınmazcelik, “Erosive Wear Behaviour of

Lubricants on Low Amplitude Oscillating Wear of Poly-

etherimide Composites,” Wear, Vol. 257, No. 5-6, 2004,

pp. 562-572.

[5] N. Sarı and T

Carbon Fibre/Polyetherimide Composites under Low Par-

ticle Speed,” Materials & Design, Vol. 28, No. 1, 2007,

pp. 351-355. doi:10.1016/j.matdes.2005.05.014

[6] P. Samyn, J. Quintelier, W. Ost, P. De Baets and G.

Schoukens, “Sliding Behaviour of Pure Polyester and

Polyester-PTFE Filled Bulk Composites in Overload

Conditions,” Polymer Testing, Vol. 24, No. 5, 2005, pp.

588-603. doi:10.1016/j.polymertesting.2005.02.012

[7] J. Bijwe, J. J. Rajesh, A. Jeyakumar, A. Ghosh and U. S.

Tewari, “Influence of Solid Lubricants and Fibre Rein-

forcement on Wear Behaviour of Polyethersulphone,”

Tribology International, Vol. 33, No. 10, 2000, pp. 697-

706. doi:10.1016/S0301-679X(00)00104-3

[8] L. M. McGrath, R. S. Parnas, S. H. King, J. L. Schroeder,

D. A. Fischer and J. L. Lenhart, “Investigation of the

Thermal, Mechanical and Fracture Properties of Alumina-

Epoxy Composites,” Polymer, Vol. 49, No. 4, 2008, pp.

999-1014. doi:10.1016/j.polymer.2007.12.014

[9] W. Chen, “Some Expe riment al Investigations in the Drill-

and T. Machaly, “Factors

Mohan, A. Ramachandra, S. M. Kulkarni, “Ma-

ing of Carbon Fiber Reinforced Plastic (CFRP) Compos-

ite Laminates,” International Journal of Machine Tools

and Manufacture, Vol. 37, No. 8, 1997, pp. 1097-1108.

[10] J. Mathew, N. Ramakrishnan and N. K. Naik, “Investiga

tions into the Effect of Geometry of a Trepanning Tool on

Thrust and Torque during Drilling of GFRP Composites,”

Journal of Materials Processing Technology, Vol. 91, No.

1-3, 1999, pp. 1-11.

[11] I. El-Sonbaty, U. A. Khashaba

Affecting the Machinability of GFR/Epoxy Composites,”

Composite Structures, Vol. 63, No. 3-4, 2004, pp. 329-

338.

[12] N. S.

chining of Fiber-Reinforced Thermoplastics: Influence of

Feed and Drill Size on Thrust Force and Torque during

Drilling,” Journal of Reinforced Plastics & Composites,

Vol. 24, No. 12, 2005, pp. 1247-1257.