Some studies on drilling of fibrous composites

Some studies on drilling of fibrous composites

Journal of Materials Processing Technology, 24 (1990) 291-300 291 Elsevier SOME STUDIES OR S.Ko NALROTRA FRP Research India. DRZLLIRS Centre...

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Journal of Materials Processing Technology, 24 (1990) 291-300

291

Elsevier

SOME

STUDIES

OR

S.Ko

NALROTRA

FRP Research India.

DRZLLIRS

Centre,

OF

FIBROUS

Indian

COMPOSITES

Institute

of Technology,

Radras

600036

summary T h o u g h a d h e s i v e b o n d i n g is a p I e f e r e d m e t h o d o f j o i n i n g F i b r o u s composites, sometimes b o l t i n g of c o m p o n e n t s is essential for operation, maintenance or inspection purposes. It i s n e c e s s a r y to drill holes in Fibrous composites f o r j o i n i n g them by bolting. D r i l l i n g of fibrous composites p r e s e n t s many p r o b l e m s like - delamination, f i b r e ~ r e s i n pullout, e x c e s s i v e tool wear, etc. In t h e p r e s e n t work, d r i l l i n g o f g l a s s f i b r e ~ e p o x y and carbon f i b r e ~ e p o x y l a m i n a t e s is studied u s i n g High speed ~ and T u n g s t e n carbide coated drills. The effect o f c u t t i n g speed, feed a n d n u m b e r o f h o l e s on tool w e a r , t h r u s t a n d t o r q u e is studied. I M T R OD U C T I O •

Advanced

Fibre

increasingly

used

applications.

This

properties tailoring

by

following

but

when

delamIBation: of i m p o r o p e r

Fibre~resin

wall of the iv. H i g h e r

an

specific the

being

mechanical

possibility

excellent

machined

they

wear

flexural

of

performance

tend

of

of plies

separation machining

to

develop

the

the

cutter

that

develops

between

plies

and drilling.

tearing

away

of

due to abrasion causes

fibre~resin

the

from

by h a r d fibres.

easy

deformation

of

hole

which

to h o l e shrinkage. powdery

chip

which

is

a health

to handle.

0924-0136/90/$03.50

where

edge.

strength

leads

Presence

separation

pulloutz

machined tool

subsequently

difficult

and

are

engineering

the material.

as a result

vi.

materials

have

delam~nation:

and e x i t s

Lower

high

other

flaws:

ii. I n ~ e r n a l

v.

Composites and

due to the

these

composites

Surface

iii.

Plastics

aerospace

is mainly

offered

characteristics,

enters

modern

their p e r f o r m a n c e .

Though

io

Reinforced in

© 1990---Elsevier Science Publishers B.V.

hazard

and

is

292 vii.Lower leading

thermal

to

Machining the

a. FRP is

b.

The

little

low

c.

gives high

by

difference

the

and

the

to

plastics

is

tool

work

the

in

Reinforcing

heat

accumulation

from

metals

due

to

the

cutting

On

The

heat

temperature

build

since

greatest

the

Though

of matrix.

causes

coefficient (carbon

stresses

accuracy.

surface

and

up

there part

in

the

is

only

of heat

layer

linear

has

of

is

composite

it

holes

metals,

it

fillers

linear

can

cause

of

diameter of

between

heat

a highly

attain

expansion

friction

amount

to

a smaller

of

between

coefficient)

difficult

show

increases

the

expansion

negative

makes

coefficient

consequently and

of

fibre

Drilled

Since,

than

fibres

temperature.

operation,

tool.

the

used.

and

of

rise in t e m p e r a t u r e .

residual

more

range

material.

the f i b r e

drill

and

vary

temperature,

machining

through

dimensional

than

composites

conductivity

during

away

rise

local

to a v o i d s o f t e n i n g

is a s i g n i f i c a n t

matrix

of

higher

dissipation

The

the

causing

wear.

in a l i m i t e d

thermal

zone

carried there

machinable

n o t be e x c e e d e d

cutting

tool

reasons:

withstand

should

in

characteristics

following

fibres

conductivity

increase

the

produced, abrasive

d. too~

wear. e. has

The

change

in

physical

to be c o n s i d e r e d Mackey[l,2],

different al. [5]

tool

have

Boldt

studied

and

material

on h o l e

also

the

of drill torque,

and

drilling

the

relation effect

the

absorption

of

fluids

and of

between

of

Miller[4]

composites. tool

cutting

have

tried

Sakuma,

material

conditions

et

and

wear

and

tool

quality.

present

Speed

speed,

by

to use a coolant.

Chanani[3]

in

the

work,

Carbonfibre/epoxy(CFRP) using High

deciding

geometries

behaviour

In

properties

while

and

Steel(HSS) feed,

toolwear,

drill

study

i8

carried

Glassfibre/epoxy

and Carbide geometry,

hole shrinkage

(GFRP)

tipped

drills.

no.of holes,

and h o l e

out

finish

etc.

on

laminates The

effe~

on t h r u s t ,

has b e e n

studied.

EXPER~MEmTAL

CFRP Carbon

and

GFRP

fibre

and

laminates glass

were

fibre

prepared woven

by

cloth

hot has

press been

moulding. used

as

293 reinforcement.

Epoxg

Hardener

Ciba-Geigy

of

HT972,

laminates A

feed

used

column

rate

Different of

to

The

strain

gauges

for

the

thrust

measurement. taken

means

The

drill and

mounted

on

drill

and

Vidicom precision,

of

are

the

fixed

of lead

The

spoke

stylus

were

made

length

2

and

the present

work

wheel

at

specified

top on

and

the

elecgauges

distances. the

of

spokes

the

for

thrust

for

the

an

strain

bottom

sides

for

hydraulic,

The

the

spindle

regular

is

the

and

used

torque

torque

are

radius

traces

laminate and

40

is

torque

holes

using

drill.

tool

wear.

It

3-coordinate,

using

type

the

a digitial

upto

drilling

is

a

video-

of parts.

measured stylus

The

tipped

measure

gauging

the

Thrust

carbide to

of

axis.

non-contact,

is

bed

intervals

using

tracing

gives

on

drilling.

for

finish

and

RPM

used

used.

fixed

holes

datum m.

56-1250

is

was

accurately

for

range

commonly

connections

at

400

Qualifier

of

the and

with

fixture

fixed

and

Thickness

wires.

the

surface

LY556

matrix.

mechanical,

For

type)

on

dynamometer

centre

controlled

sample

wheel

measurement

upto

the

for d r i l l i n g .

are

optical.

electro-optical,

inspection

tip

arms

speed

used

forces

and

aligned

measurements

as

dynamometers

Independent

by

machine

HSS

of

(spoke

the

used

with

was

cutting

electrical

bonded

(Resin-Araldite

was

machine

mm/rev,

dynamometer

are

sgstem

Ltd.)

8ram.

types

measurement

trical

was

drilling

0.03-0.40

pneumatic,

resin

microprocessor

perthometer.

surface

display

of

A

profile R a , R t,

Rz

diamond

along and

the Rma x

va lues.

RESULTS

AI~D D I S C U S S I O N

The

results

Following TOOL

WEAR

i.

Both

chisel

difference

ii.

Tool due

edge

F1ankwear

The

is

the

observations

A.

holes.

of

to

wear

is

much

more

is m o r e

greater

are

wear

is

above

study

made

and

from

CFRP

abrasiveness

in c a s e

laminates of

plotted

carbon

in

Fig. 1-15.

figures:

increase

compared

pronounced for

these

flankwear

more

are

to

the

with

the n u m b e r

chisel-edge

of

wear.

o f GFRP. as

compared

fibres

to G F R P .

compared

to

This glass

294

~

Carbon- epoxy HSS 1000 FeedDrill 0.06mm/rev. Speed 1250rpm 800

=~.~....-----=

6oo

L.oo 200

~

ear =

I

lO

30

E ~.

13lass- epoxy HSS Drill 500 Feed 0.06 mm/rev. 400 Speed 1250r p m

~

"~

300

Number of holes FII3.1

4o



~

,I0 @g

frank wear

200

~IOO f - ~ - - ~ -/chisel edge ~ar 5

i

10 20 30 Number of hotes FIS. 2

Carbon-epoxy Carbide drill 120 Feed 0.06mm/rev. 100 Speed 1250rpm

~0

/ J /

/

,)

80 ,_ 60 tlO OJ

~= /,0

"chisd edge wear

o 20 I--I

!

I

100 200 300 Number of holes FI5.3

~00

295

Glass-epoxy 60

50

Speed1250rpmJ

,=

,o 30

/ ~

_20

lchise[ edgewear

O 0

~10 I

I

I

100 200 300 Number of ho[es FIS./+ 80 HSSdrill 70 -Feed0.06mm/rev. S ~

~0

"Carbon/epox

60 ~- 50 ._ ~0 u~

'=30

r-

I--

20' 10 I

lo

I

30

/+0

rbon/epoxy ~-

I

2'o

Number of hotes FI6.5

,=5 !

¢, 3 ~2 I--.1c O

Speed 1250 rpm I

I

I

10 20 30 Number of holes FIS. 6

/+0

296

w20 "!

5Lass/e poxy.~.~ " ~

L. t-"

Carbide dr't[[ Feed 0.06mm/rev Speed 1250 rpm

10 5

I

0

100

I

200 ~0 Number of ho[es FIG. 7

400

E 6 L.I

,v-

o~ /4

E3 O

2 1

O

~ / e p o x y

0

I

100

I

__.

I

200 300 Number of holes FI5.8

400

E

:E 5OO °~

4O0

L

300

HSS drill Speed 1250 rpm

2OO m

1.1_

100

Glass/epoxy after 20 holes 0 I ._, 0.0z~ 0106 0.1 0.19 Feed, mm/rev FIG. 9

297 fi bres. iii.

Carbide GFRP

for

holkes is

In

v.

drill,

excessive. after

from

of

CFRP

0.06

wear

While

40 holes

in

the

than

tool

case

RSS

wear

of RSS

drill

even

both

after

drill,

tool

400 wear

itself.

flank

wear

to 0 . 1 9 m m / r e v .

is m o r e

better

reduces

while

pronounced.

in

(Drill

a

little

case

speed

as

GFRP

of

is k e p t

feed

is

reduction

constant

at

RPS).

For

1000 600

much

carbide

drilling

flank

1250

performs

With

large

increased in

drill

CFRP.

is n o t

very

iv.

tipped

and

GFRP,

RPM, RPM

flank

while

(feed

B. T H R U S T

AND

is k e p t

i.

Using

RSS

drill,

holes

for

both

than

holes ii.

for

is m u c h

Unlike

using

drilling fibre

more

both

rapidly

wear

at

is

at

not

drill

much

speeds

above

affected

beyond

with

number

O.06mm/rev).

Also,

is

both

laminates. force

thrust

for

CFRP or

values thrust

Because

with

for

number

of

lamlnates. less

constant Torque

of higher

drill

and

values

torque

the

are "much h i g h e r value

materials.

between

and

in

more

the

increases

thrust

increase

torque for

CFRP

continuously

materials,

pronounced

frictional

Hence,

thrust

GFRP.

drill of

flank

constant

the

thrust,

aSS

increases

CFRP,

TORQUE:

of

CFRP

wear

for

are

after

i0

is

higher

abrasives,

CFRP

of

holes

ca~rbon

mate~[l-/S,

higher

for. C F R P

in

more.

than

for

are

not

GFRP. iii.

Using

much

affected

carbide after

carbide upto

drill

40 holes, less

same

case

of

drilling

CFRP

than

for

feed

0.06

mm/rev. RSS

as

GFRP.

gradually the

both

torque

both

is

after

after

aSS

For

drill,

for

holes

that

with

increases

drill,

h o l e s . Also,

400

while

or

Using

400

after

more

iv.

tipped

both

40

study,

keeping

speed

as

feed

is

the less 400

with

with and

drill

increased

of

drill.

at

from more

are

was

0.05

drill

drill As

in

to

for

RPM

RPM,

is the

higher

1250

1250

with

~SS

carbide

R SS

speed

thrust

with

torque

constant

is

torque

that

holes

holes

Increase

and

magnitude than

thrust

this

materials.

thrust

and

thrust

O.19mm/rev.

pronounced

for

CFRP

laminates. Torque of

CFRP

increases

torque

is

with

minimum

feed at

in t h e feed

case

rate

of GFRP, of

while

0.10mm/rev.

in and

case it

298

HSS drill Speed 1250rp

30

~..~<~arbon

/ epoxy

N--

-~ 20 &. r-

1--

10

~_.1.-----°'-~6[ass/epoxy

0

I

I

0.04 0.06

0.I

Feed rater (mm/rev) FIS. 10

0.19

driLL ._.5 E

Y~

w3

g20

I

0.03

I

0.1 Feed rate, (mm/rev) FIG.11

0.06

HSS drill,

0.19

Feed 0.06 mrn/rev

E

~5oo pox), after 10 holes

LO0 3

g 300 2OO ~I00

~ a f f e r 0 25O

I

500

20 holes I

1(~30 1250 Speed, (rpm) FIG 12

299

=,,.,,,~----~~n / epoxy

25

20

drit[

HSS

"15 ~ 10 e-

~ p o x y

i-- 5

I

I

t

500 1000 1250 Speed,(rpm) F 15. 13

0

H SS driLL

,=5 [ a r b o n ~ O,I ..,I cr2

¸

tO

i-. 1 I

i

I

500 1000 1250 Speed, (rpm) FIG.lZ, HSS driLL E

15! I¢1 e-

i

¢Q

"C3 2

t

0

10

t

I

30 Number of hoLes FIG. 15 20

~0

30O increases that

rapidly

in d r i l l i n g

is ideal v.

at d r i l l

Using HSS

not much 1250

for

In

case

in

the

to

1250

case

drilling

of CFRP

value

after

torque

torque

indicates

0. 10 m m / r e v .

reduces is

at

0.06mm/rev.

650

there

RPM,

is

500 to

from

thrust

is

CFRP.

much as

affected

speed

better

by s p e e d ,

is i n c r e a s e d

to

use

higher

while

from

500

speeds

in

drills.

(Ra

is

This of

is i n c r e a s e d

Around for

is not

it

value)

increase

20 h o l e s

constant

materials.

with R S S

value

f e e d rate

as s p e e d

it is m a x i m u m

finish

0. i m m / r e v .

drill

feed

values

indicating

of CFRP

Ra

the

of GFRP,

Surface Fig. 15.

keeping

both

RPM.,

rate beyond

o f 1 2 5 0 RPS.

in t h r u s t

GFRP and

for

feed

CFRP with HSS

speed

drill,

change

RPM.

minimum

for of

with

very

of

holes

number

in

GFRP

of holes.

is

shown

Increase

in

in

Ra

rapid.

COJCLU$IOmS

In flank

general, wear

performs wear,

is

much b e t t e r

thrust

compared

tool wear higher

than

and

torque

to G F R P .

This

of c a r b o n

fibres

increases

than

compared

chisel

HSS are is

drill much

mainly

to g l a s s

with edge with

the n u m b e r wear. both

higher

in

due

the

to

the

of holes

Carbide materials.

drilling higher

of

and

drill Tool

CFRP

as

abrasiveness

fibres.

REFER EB CE$

I.

Bruce Nackey, "A s o l u t i o n to p r o b l e m s o f d r i l l i n g r e i n f o r c e d p1asti cs", 35th Annual Tech. Conf. , 1980, Reinforced P l a s t i c s ~ C o m p o s i t e s I n s t i t u t e , SPI. , Inc.

2.

B r u c e M a c k e y , "A p r a c t i c a l s o l u t i o n for m a c h i n i n g o f a c c u r a t e , clear, burr free holes in Kevlar composites", 37th Annu~ Tech.Conf. 1982, Reinforced Plastics~Composites Institute, SPI , Inc.

3.

J.A .Boldt drilling",

4.

J.A. M i l l e r , Corpn.

5.

and J.P. Chanani, Northrop Corpn. "Drilling

"Solid

graphite~epoxy

state

at

machining

Lockheeds",

S a k u m a , Yoko a n d Seto, "Study on d r i l l i n g B u l l . , o f JSME, V-27, p. 228, J u n e 1984.

of

GFRP

and

Lockheed

and

CFRP",