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2.3

Joint formation in ultrasonic welding compared with fretting phenomena for aluminium

Joint formation in ultrasonic
welding compared with fretting
phenomena for aluminium
J.L. HARTHOORN
Philips Research Laboratories, Eindhoven., The Netherlands.

Joints between aluminium sheets have been formed using two different processes. The
first process is ultrasonic welding using a vibration frequency of 20kHz. The second
process is fretting where two sheets are clamped together and an oscillatory relative
movement of small amplitude is applied to them. The frequency is 30Hz and the
amplitude is 5 ,um. After a certain number of vibrations a strong joint is formed
between the sheets. The following parameters were chosen to be equal for both
processes: the amplitude of the relative movement in the contact plane, the contact
pressure and the number of vibration cycles. The joints obtained from both processes
were examined using tensile shear tests, scanning electron microscopy and metallographic
sectioning. We conclude that both types of joints are very similar and consequently
formed by the same mechanism. It follows that joint formation in ultrasonic welding
and in fretting of aluminium must be ascribed to plastic deformation of an interfacial
layer. (In our case about 30 ,um thick). Diffusion and recrystallization do not play
an important role.

Introduction
·~ to

the joint formation in ultrasonic metal welding no
accepted theory exists. A number of possible
basic mechanisms, which are mentioned in the literature ,
are reviewed in the next Section.

~ nerall y

Fretting occurs between con tacting metal surfaces which
undergo small oscillatory relative displacements. The
firs t stage of fretting i.e. , the formati on of j unc tions
(microwelds) seems to be analogous to ultraso nic metal
welding. The main difference is the lower vibration fr equency of the fretting process, which is roughly x 1000
lower than the frequency of the ultrasonic we lding process.
To verify this analogy we made ultrasonic welds in aluminium
and compared them with aluminium joints obtained by
fretting. The parameters (pressure in the contact plane,
relative vibration amplitude in the contact plane and
number of vibration cycles) were chosen to be almost equal
in both the ultrasonic welding and fretting experiments.
The aim of the comparison was to inves tigate the mechanism
of joint formatipn in ultrasonic welding of aluminium.
For the study of joint formation the fretting process has
several advantages:
a) Because of the low frequency the process can be

followed cycle after cycle . The growth of the joint can
be studied easily this way .
b) During frettin g no gross temperature rise occurs, so·that
melting, diffusion and recrystallization cannot play a role.
ln our experiments the joints formed during the first stage
of the fretting process were not broken because of the
relatively low amplitude and the small number of cycles.
The word ' fretting' is connected with the formation of wear
debris (second stage offretting). We, h owever, use 'fretting'
in the sense of 'the first stage of fretting using relatively
small amplitudes and few cycles'. (This type of joint
formation could b e called 'subsonic welding'.)

Ultrasonic joining
In ultrasonic metal welding the parts to be welded are
clamped bet wee n a 'so notrode' and an anvil (Fig. 1). The
'sonotrode' vibrates pa rallel to the interface of the two
parts and after a certain time a joint is formed .
The frequency of vibration is generally between 15 and
100kHz. The vibration amplitude of the 'sonotrode' can
range up to 30 ,urn. The bonding time depends upon
rna terial properties and lies between 0.1 s. and 1 s. The
clamping force is so chosen that the pressure in the interface
is about 0.3 times the tensile strength of the material.
Ultrasonics International 1973 Conference Proceedings

43

J. L. Harthoorn

Ainbinder and Tikhomirova [ 1] observed globular oxide
inclusions in copper after a weld time of 2 s. They concluded
that local melting took place. Frisch eta/ (2] reported
material being squeezed out of the interface during welding
of stainless steel in vacuum (time ~ 1 s.) A highly plastic
state of the material is assigned as an explanation.

Sonotrode

Weare, Antonovich and Monroe (3] suggested melting but
did not observe any evidence.
Fig .1
A possible arrangement for ultrasonic welding
of sheets.

In order to join metals, clean surfaces must be brought
together within a distance comparable to the interatomic
distance . Interatomic attraction then causes bonding.
Such close contact can be obtained in the following ways:
1) Melting of an interfacial layer
2)

Plastic deformation of the contacting surfaces

3)

Recrystallization of the contacting surfaces.

r

~r

effects such as diffusion and mechanical interlocking

arc also considered as phenomena causing joint formation:
Melting

With regard to interfacial melting, only a limited number of
observations suggest that melting occurs. In the majority of
cases however there is strong evidence of the absence of
melting.

No sign of melting was observed by many others [ 4 to 11] .
This is consistent with temperature measurements in the
ultrasonic bond zone which fall below the lowest melting
point of the bond materials (see Table 1).

Plastic deformation
In regions where the surfaces are in contact lateral vibrations ·
bring about shear forces in the interface during ultrasonic
bonding. Plastic deformation is observed which causes
removal and/ or dispersion of surface films (e.g., oxide layer,
adsorbed gases, lubricant films) [3, 5,15 to 18] . By the same
action clean surfaces are brought close together and metallic
adhesion can occur [3,4,8,9 ,12, 13,19 ,20].

Recrystallization
The shape of a surface changes during recrystallization.
Hence crystallites can grow one against the other to form
atomic contact between two surfaces [21]. Recrystallization
is reported by Okada eta/ [ 14] in ultrasonic joints of Cu,
Zn and AI, Ainbinder et a/ [ 1] in Cu and Jones eta/ [4]

Table 1
Maximum temperatures observed during ultrasonic bonding of different materials

Author and year

ndin

Bonded material

Melting point
of lowest
melting
material T
m
in °C.

Maximum
observed
temperature
in °C.

12 1960

Chromei ·Aiumel

1400

370

13 1961

Fe-con st antan

1300

600-850

1080

230

Weare

3 1960

Monei·Cu

Jones

4 1961

T3 alclad Aluminum

660

470

CP-copper (to itself)

1080

300

Fe (to itself)

1450

660

AI (to itself)

660

630

660

500
40% ofT m

Ainbinder

1963

Okada
Daniels

14 1963
8 1965

AI (to itself)
Various materials

Ginzburg

15 1967

M3 copper

1080

730

660

250

Fe-constantan

1300

260

Cu-constantan

1080

260

Au (to itself)

1080

Cu-AI
Hazlett

Joshi

44

9 1970

16 i971

Au ·AI

660

Au -Cu

1080

Ultrasonics International 1973 Conference Proceedings

2.3

Joint formation in ultrasonic welding compared with fretting phenomena for aluminium

4-T6 aluminium and nickel. The last authors state
role of recrystallization is by no means established.
diffraction patterns of the welded zone Heymann
[19] could not detect any recrystallization. The
re reached during welding does not necessarily
the recrystallization temperature (see Table 1).
r, the bonding time is, in most cases, short compared
time required for recrystallization, which of course
strongly upon the temperature. (In the case of the
used in our experiments 30 min storage at 540'C
cause any recrystallization}. We may conclude that
nee of recrystallization, if any, on joint formation
understood.

. tis evident that intimate metallic contact must occur
diffusion can take place. Hence in ultrasonic
diffusion must be considered as a phenomenon
about after bonding i.e., bringing surfaces into
dence for bulk diffusion in a Cu-Al joint is given by
authors [15,17,22]

Ginzburg eta! [ 15] remark that it is impossible to account
the observed diffusion phenomena by the measured
They suggest that diffusion is stimulated by
plastic deformation. Kulemin and Mitskevich [23)
investigated the enhancement of diffusion under the
'' · influence of ultrasound. The diffusion constant could be
. increased by a factor 7. The times, however, are very long
(1-3 hours) compared with ultrasonic welding times. As
yet, therefore, no conclusions concerning diffusion in
ultrasonic welding may be drawn from this work.
No detectable diffusion is reported by Daniels [8] in a
Cu-Ni joint and Joshi [ 16) in a Cu-Au joint; both using
microprobe analysis.

In the first stage, oxide layers and lubrication films
are disrupted by the oscillatory relative movements of
the contacting asperities. By plastic deformation
clean metal comes into contact and junctions or
microwelds are formed by metallic adhesion [28,29].
In the second stage of the process, these junctions are
broken and wear debris is formed. In a reactive
atmosphere chemical reactions (usually oxidation)
can occur at the interface; reaction products are then
formed. A progressive damage of the surfaces is
observed.

Apparatus
Ultrasonic equipment
The apparatus for ultrasonic joining was developed in our
laboratory and consists of:
a) a piezoelectric transducer [30]
b) a bicylindrical amplitude transformer which is spherically
thickened at th'e end to form the weld tip (Fig. 1).
c) an anvil, which can pneumatically be pressed against the
weld tip
d) a generator with timer unit. The generator is automatically
tuned at the resonance frequency of the vibrating system.
The maximum electrical power is 400 Watt and the
nominal frequency is 20kHz. Voltage and current at
the transducer terminals and amplitude at the weld tip
can be monitored.

Fretting apparatus
For fretting experiments a simple apparatus was built (Fig. 2).
The testpieces are two sheets. Sheet 1 (dimensions
40 x 12 x 2 mm 3, see Fig. 2) is fastened upon an anvil, the
other sheet 2 (dimensions 40 x 12 x 1 mm 3 ) is fixed to a
lever, which has the centre of rotation P. The middle of this
plate is situated over a rectangular hole in the lever.

A phenomenon which can also play a role in the ultrasonic
joining of metals is mechanical mixing and interlocking.
This phenomenon is observed with scanning electron
microscopy by Hazlett [9) and Joshi [16) . It points to
plastic deformation without appreciable metallic adhesion.

On the other end of the lever a vibrator is mounted (not in
the fig.). The frequency is 30Hz. Hence, by vibrating the
lever, sheet 2 can make an almost linear movement in the
direction AA. The maximum vibration amplitude at A is
40 {J.m. The middle of the moving testpiece 2 is pressed
upon the fixed sheet 1 by means of a spherical pin . The
radius of the end of the pin is 6 mm. When the lever
vibrates the pin can follow the mo·tion of the upper testpiece. At the end of the vibration period a joint is formed,
between the two test-pieces, immediately below the pin.
The amplitude of the vibration is measured at A by means
of a "Fotonic Sensor" (a non-contact optical apparatus
manufactured by Mechanical Technology Inc., Lathem,
New York, USA). The sensitivity is 0.2 {J.m. The shear
force in the fretting zone is monitored by means of a strain
gauge.

Fretting

Experimental results

When metal surfaces are in contact and undergo minute
oscillatory relative displacements fretting can occur. The
vibration frequency can go up to about 100Hz and amplitudes up to several hundreds of microns. Fretting is a
complex of adhesion, wear phenomena and chemical
reactions [24]. Thomlinson [25, 26] was the first to discuss
this phenomenon and called it"fretting corrosion", Later,
the term fretting was generally used.

Experiments

Hazlett and Ambekar [9] observed Cu-constantan joints
with the scanning electron microscope. From micrographs
a faint evidence of grain-bounda:-y diffusion could be
concluded. However they did not observe such a
phenomenon in a Fe-constantan joi_nt.

Mechanical interlocking

A review concerning the phenomenology and the mechanism
of fretting is given by Hurricks [27]. A very brief outline of
the generally adopted theory follows here:

Aluminium sheet material was used. (A1 ~ 98%. Si ~ 1%,
Fe ~ 1%; Vickers hardness 38 VPN; tensile strength 120
N/mm 2 .)
The rolled surface did not undergo any treatment except
degreasing with acetone. Experimental parameters are given
in Table 2.

Tensile shear tests
Tensile shear strength of the ultrasonic welds and the
Ultrasonics International 1973 Conference Proceedings

45

• J. L. Hanhoorn

I
Sheet 2

Strain gauge

Figs Sc and 6c we see that the interface has disappeared
over large regions. The related Figs Sd and 6d shows that in
the whole interface severe plas tic deformatio n h as take n
place. The long grains of the rolled parent material are
fragment ed. The thickness of the deformed layer is
15-30 jJ.m, which is confirmed by Figs Se and 6e.
Especially in the ultrasonic joint, the initiation of cracks can
be observed at the periphery of the weld (Fig. Sa) . In a
joint obtained by fretting this is less clear ( Fig. 6a). However,
when in fretting an amplitude of 6.5 jJ.m is used cracking is
also observed.

A~

Sheet 2

Some additional experiments, using polished surfaces , show
the growth of the bonds during fretting (Fig. 7). The
increasing number of bonds and their increase in length
can be seen.

Discussion and conclusions
Analogy between ultrasonic and fretting
experiments

cig . 2 Top view of the fretting apparatus with a section
hrough AA'.
join ts made by fretting was determin.e d (Table 2) . The
welded area of the joints was estima ted by mean s of a
microscope using an ocular with a scale division .
In fre tting, when using larger amplitudes and/or a greater
number of cycles than in the experiments desc ribed in
Table 2 , the joints are broken du ring the fr etting process .
Initially a fa tigue stria ti on pa ttern is observe d at the periphery
of the fretting"zone in the pee led j oint , resulting in a
reduc tion in joint shea r strengt h . An a mplitude of I 0 }J.m
an d 5000 cycles resul ts in an almost comple tely dest royed
joint area (second stage o f fr ett ing).

Scanning electron microscopy
Peeled joints we re exa mined with a scanning elec tron
mic rosco pe . The micrograp hs of an ul trason ic weld are
shown in-Fig. 3 . Fig. 4 shows a joint made by fr e tting.
Th e dar k regio ns in Figs 3a a nd 4 a a re u nt ouched by the
"-' rocesses. Oblong ro ughened regio ns, where joining t ook
place , are visible. The lo ngest dim ensio ns of these regio ns
is parallel to th e direc tio n o f the movement during the
processes . These oblo ng junct io ns pa rtl y ove rlap or to uch .
A charac te rist ic of a rolled surface is the occurrence of
'"chan nels and ridges" running parallel to the direction of
rolling. In the " ch annels" n o me tall ic contac t takes place
and hence we see therr, as lo ng dark ve rtical line s on the
microgra phs ( Figs 3a and 4 a) . These are not ob se rved with
specimens which were polished befo re fr etting (Fig. 7).
The brok en j unctions have the ch aracte r of duc tile broke n
material. This is show n in Fig. 3b fo r a n ult raso nic weld a nd
in Fig. 4b fo r a joint obtained b y fre tting. For these two
micrographs the spec imens we re til ted ab ou t 70° to see the
relief of the surfaee.

Metallographic studies
Metallographic sectio ns we re made. The sam pl es we re
vibrato ry polished and imm ediate ly a ft e rwards anodized .
Fig. 5 shows micrographs of ultraso nic joints and Fig. 6
shows sections of joints obtain ed b y fre tting. From
46

Ultrasonics International 1973 Conference Proceedings

Pressure in the contact area and the number of vibration
cycles are almost equal for the two processes (see Table 2).
The amplitude of the weld tip was 15 ~tm ; the amplitude of
the upper plate in the fretting apparatus was 5 jJ.m. In
ultrasonic welding slip occurs at three interfaces (a) weld
tool- upper joint member ; (b) between the joint members ;
(c) lower joint member- anvil. Also elastic vibrations of
the anvil occur.
Thus the amplitude of the relative displacement(= slip)
between the two comp o nen ts is smaller than the amplitude
a t the weld tip. It is al so plausible that the slip betwee n
the joint me mbers de creases as the joint grows. As to the
value of th e slip between the specimen little is kn own. We
estimate the va lue to be betwe en 2 and 8 JJ.m. The reasoning
is as foll ows :
Fi rs tly, in fr etting experimen ts no me tallic bon ds were
found when the ampli tude wa s 2 ,urn; with an am pl itu de of
I 0 ,urn and 5000 cycles almost all the bo nds in the j oint
were destroyed .
Secondly, a reference [3 1] (quoted by Dip pe [32 ] ) reports a
value of 8 ,um slip am plitu de between the specimen at th e
beginni ng of the we ld , dec reasing to 5,um a t the end of the
welding peri od ; th e ti p a mpli tud e is 12 ,um . By ch oos ing an
ampli tude ofS ,u rn for the fretting expe riments we ass um ed
that thi s would be close to the mea n value of t he ac t ual slip
am plitude in ul t ras onic j oining.

The f ormation of joints in fretting
We base the following pictu re o f the fret ting p roce ss u pon the
exper ime ntal obse rva tio ns. Initially the surfaces make contact
at the aspe ri ties . The la teral vibration cau ses normal and
shear force s in the con tac t zone . Thus the surface layer
(oxide layer, adsorbed gases, contamina tions etc). is locally
broken and /o r disperse d in the parent ma te ri al. At those
points plas tically defo rmed clean metal comes into con tact
and the firs t bon ds are fo rm ed . The dim ensions o f these
bonds are of the o rde r o f 10f1m (smallest spo ts in fi g.7a).
These ini tial bonds grow in the direction of t he vibratio nal
moveme nt by repea ted plas tic deform atio n. A t the gro wth
" fr o nts" the surface laye r is destroyed by deformation.
Du ring follow iag cycles new clean material is brou gh t in to
contact and me tallic adh esion occurs. Hence the grow th
" fro nts" of the bo nded are as p ro paga te and bonds become

2.3

Joint formation in ultrasonic welding compared with fr etting phenomena for aluminium

Table 2 Experimental parameters and results
Ultrasonic welding

Fretting

Thickness upper sheet

1 mm

1 mm

lower sheet

1 mm

2 mm

20kHz

30Hz

Vibration frequency
Amplitude of the weld tip

15·20 ,urn

Slip amplitude in the interface*

about 5 ,urn

5 ,urn

Number of cycles

6000

5000

Clamping force

900 N

60 N

Welded area

17 ± 3 mm 2

Pressure in the contact area

53 ± 10

Tensile shear strength of the jointst

55 + 5 N/ mm 2

* See opposite

t

N/ mm 2

1.3

± 0.2 mm 2

46

± 8 N/ mm 2

50

± 4 N/mm 2

With standard deviation

Fig. 3a Scanning el ectron mi crograph of a peeled
ultrasoni c bond in aluminium . Direct ion of observation
perpendicular to the joint interface.

Fig . 4 a Scanning electron micrograph of a peeled joint
obtain ed by fretting. Direction of observation perpendi·
cular to the joint interface.

Fig. 3b Scanning electron micrograph of a peeled ultrasonic bond in aluminium.

Fig. 4b Scanning electron micrograp h of a peeled joint
obtain ed by fretting.
Ultrasonics International 1973 Conference Proceedings

47

1. L. Hart/worn

..

. . .......

-

..

"!" . - . •

~

.. .

·

-

. :. ·. - -- ~-

· :-: - -.~ -· ' ~--_:. .
.-... ..

_,.

.........

...

-

_

-- ·"'

:

.

:

..~....

·....- .;

:: . .. ·

..... -

:

- .-~

..

.

. ~

,. --..:-:~: :..
.

.......

:

..

..

--

-:·-, ...

-._:·_. ;

--



_

.. -··-.
. ·-

' :

..

· ~. ­

·.,.

·- .....,

___·: .
--J , · ·

~ .



_:

-

.... ... _ ..

:_.~ :: -·· - .

·, .

.

._-..;.

-. :

---

-i. ·-·

·- -

--

·.-.;.

...

"':

··.. . - .'
. .... .

.. .. ., -.
.. -·

~-

_':"

~

'a:

-

..:.=---·:::·:::..

.- . '

-· . ......

. -~

·.-·...·-.--. -· .

·· ·~

"'-;..~~a .

...........

·.

-~·

.......•..·
·

'~ ·

:· -~·· . .

·. .·.
.

• . -·

-~

.

-

. .-

'

"",;

....

·-

....

-.

..

so..u-,
...... ··

Fig . 5a . Metallographic section of an ultrasonic bond in

.... .. .. .

-...• ·
-~ -

..:
50~

.I

.~

. . ·.

.

.-

Fig. 6a

Section of a joint obtained by fretting. As Fig. 5a.

Fi g. 6b

Sect io n of a jo int obta in ed by fretting. As Fi <J ~il.

aluminium.
Direction of sectioning parall el to th e vibration directio n
during joining.
Oberved using unpolarized light.
'-.......· Region at th e periphery of the joint.

Fig .Sb Sect ion of an ultrasonic bond .
Direc tion of sect io ning as Fig. 5a.
Observed using crossed po lari zers .
Same reg ion as in Fig. 5a .

. .... _.

..

..... .

.

~

.•.

. . ·.~

.-_,; .·

-

-~-

..

.-...

0

--

·•



-._.: .

...

~"

--.

·.
.. :··. .
~ ·-:

-

_... _.

....--.... ·. ···..---.-: ·

._
: .... <- . ••

..
·.

.. ·

-

. .............
__

... .·

:.. -

._,.

,

_.. _ .

. --·
.

. -·

Fig. 5c Section of an ultraso nic bond.
Direction of sectioning as Fig. 5a.
Observed us i ng un po lari zed light.
Regio n in t he central part of the joint .

.--

Fig. 6c

,_,. .
- -:

... - -

- .:;::J--·

: .:.· - ·



50 A-

•.

~

... _::

- -~

~

~

..·
.:.

·.. -·

~- ·--

b

•.

~.

--

... .......

.

:. ~

Section of a j o int obta in ed by fretting . A s Fi g. 5c

I
48

Ultrason ics Intern ational 1973 Conference Proceedings

j

2.3

Joint formation in ultrasonic welding com pared wilh fre tting phenomena for aluminium

Fig . 5d Section of an ultrasonic bond. Direction of sectioning as Fig . 5a . Ob se rv ed using crossed polarizers.
Same region as in Fig. 5c.

Fig . 6d

Section of a joint obtained by fretting. As Fig. 5d

Fi g. 5e Sect ion o f an u l traso ni c hond.
D irect io n of sect iorlrrHJ pc r·pcnd icular to th e vibrati on
dire ct ion ck11·inu io ini r1g
Obse rved usi n~ cross>'d po l;11·i ze rs.
R e~ti on in the central p;crt o f th e ioi111 .

Fiq 6e

Sec t ion o f a jo i nt ob t ained by fretting. As Fig . 5e .

oblo ng in the: dirclli•'ll uf tile' llll'VL'IIIc rlt (l : ig. 4a and Fig. 7).
Remuval <lillie· ·,1;•'! ,·l. r\· e·r ",·,·ur-; 'lliJiili,IIH.' UUSiy wi th the
i!rnw tlt "~'tir e' h"11' 1'
\ 'tire' l''''cc'" c ~>t ll illues Jn inc rea sin g
lllllllhe·r "!' J-," " d' _., ,,,c. lllllle'\i , le'~J <.:c lr1 this manne r th e
pi~JS t ic~illl de·l."ilile'cl lliie'JI ~IC I ~il l.rye·r I'> C.\tl' lllied an d th e
j 11 iIIi i-; I.e> lllle'ti
Th e bonded ~ r rc ~1s ~ , ,,,,. l,,,,· ar ds :1 lc n<z llt ,, f seve ral hundreds
uf llliL'!'<llll"l•''' ( 1- i~s ·t dtld 7 ) ~Jtld l'in-.ilh· l':trt ly ove rl ap . The
l::trge r the sl tp a tllplituJ,· the· l'ii slcr tl1 c gruwtl r. Fretting
c.\p criJIIct lts with an ~unp litu de· "f ~U /1111 a nd 200 vi b ra ti on
eydcs yidd.t c> itll'> l'.tt lt the sa me streng th as the joints
rnull i<mcJ in I .tbk ~I ~ 000 cyL·Ics: 5 f1111 ) .
After '>el·cnl tl li ' ll\~!rld> "' c\ _lc, II'JtiJ ~111 :llnpli t ude o f 5 fl nl
tk,tn!c'liiJIJ "' ti"· llcJ,i bc'i!ilh :11 'tile' J'c·rq>ll cry ( figs 7c a nd d).
rile Llr:,:c l the: .l:!!plit:.!c'c' ti lL' l,i )lc r tltc destnlct io n.

Compar iso n of the res ults and c o nclus i o n
Th e resul ts of the tensile sltea r tes ts exa minat ion with the
scan ni ng ckctmn ln icrusc·,Jpc :tnJ rncta ll ug ra ph.ic sec tioning
show~~ strik ing simi!:t•it '- b.' tllc'L' Il ultrC~sonic joints and
l'rctted j<Jints. usi ng :di'lllSt cqu:il p:1ra!nctns in bo th proct'ss~.'s . l t is _. ,,11:i •.•. c.: '·":" ..... c: quality uf the tensile

·he·:11 \(IL'II;,"IIi , tiJ ,· e'.\l'lcilc.l' ,,J •'''["":'. J, ,, n,kd a reas in
'"' ''' tvp•'' •-" j11i11h :111<1 1l ·' ,r,,, .. ,·, · <ipl:~, t ic":illy deform ed
ll l lc' rlac cs i11 t!tc scc tiu ns. tlut tile ft1111l atinn o f joints in
tiltr~1 Sn11 i r weldini:! :111d d uri n\! tile l'ir\1 s i ~ I \!C t' f fre ttin g
c':lll he· ,i,c'llllc·d [II tile· \:lll lc' .. ,,,, .!111,111.
lkc-.111,,. "' tliL' !"11· (' 11 \\'l'i ····: 1 'I tiJ ,· frc'l lillg e xpe ri-::lCI\ 1
LthiiUI I~ ill \\ in the I'IC\c'! '[ c'\fll'lll lle'llh) . gross tempcr:tlurc
ri :;c dues 11"1 urcu r in frct t;n~ . Su temperatu re effec ts
<:: t•: IJ ~'' dillu'>i,ll l ~111d r-cc11 ''JJ iinli "ti .: :~r1 c' \Cr t lit tle
ttilluc nL·c u1t thi s pmcc ss . T it ~.· onilpuss ib le mec hani sm
'''' j11 ittl f•JJIJ I:Ili u n under t~ti; c" ndi tl ••n is pL1stic defo rm Jti ·.1 :1
as ·a lr cadv dcscrtbcd.
I lie·": ct>tl> tde l:tli u ns k :1d t • •'ill t'ina l cilllc"l us io n : Joint
J·,,,,lu ti<JII 11 1 ult r:JSullic' ll'l'•e:111g •'I :illl111illiu111 is caused by
pLi.,ltc dchr!JJ:ili"li.

11 • tJ·,• '""· !. ,,,_.c lll ~ 11 tit : !''.,,., __·:11!1 ,k k· rme d as pe riti es .
llltc·le' >ill l:icc IJ1·e'f\ ~Ill.? 1'1 ,:,.
c!h;lc'l,..;d :tn d adhesion
"C: -.''11'
. , lie'"' Slli, rli h" 1Hh ~! ·'''- 11 1 tile· dirclt io n o f th e
\i brj ttnv lllOVc' tJW nt. In tlih i.1a1 tire ll'iJole area is weld ed
:il·t,' r a c.c rt :ri n num be r of vibut1 u ns and J pl astically det\ •rn Jcd interL1c Ld i:J ycr , 11 itil J tltic:l-.n.css o l' abo ut 30 j.1m ,
comes into existence. T cm;>ciJturc- ciTecrs such as diffusio n
anJ rec rys t:tl!itJ ti on do nut !'b\ J rok in this process. They
c::lll uccu r d u rin g ultraso ni l' 1•:elding but do nut primaril y
,·ausc· the furm:tt io n of t he j,_,inr.

Ul trason ics Internat iona l 19 73 Confe ren ce Proceedings

49



·=

z=wn

rrw

..

....,_

_

J. L. Hart/zoom

a)

after 100 vibration cycle s

c)

aft er 1000 vibration cycles

b)

aft er 300 vibration cycles

d)

aft er 5000 vibration cycl es

Fi g. 7
Scanning elect ron m icrographs of jo i nts obtained by fr etting of pol ish ed specimens. Vibration ampli t ude and pressure
as in T able 2.

Acknow ledgements
I· ·e ll tu thad; ~lr II. Peeters for carry ing out the experimen h
1lr .J .L.C. D:.wms for 111akin g the sc anning elec tron
tn inllg raph s.

~~ ' -~

I ~1 1 11 in de bte d l\' Dr 1\ . ll ul;;t f" r th e· helpful di scussions.

Couco ub s. A. fi •H WL> rk ul trasr,n i,· b" ndin £. Pro ceedings of
th e 1970 U ccrrr111 i c 0JIIIfiO !I CIII S Con /(n·n ~·e. \\ .1 shingt;n DC
(l' S.-\1. l 3- 15 \1 :". ( 197 0! . p p. 5-!9-556 .
1>

Da nic'ls, li.P.C. Ultra so nic wcldin~. U rraso nics. 3 (1965) ,
pp. 19 0-196.

9

ll .l kt t . T.ll. :111 c! -\rn bL'kt r. S .\ 1. \, :diti•lllcd < >Jd ies on in te rface·
ult- "'·· n ic weld s
lt'tl, i l>!g .f,,um a! 49 . (1 970), I'P· 196 -20 0 .
..
,

t T~l p~..~ra t ur ~..· ' ~t nd l··, Jndin ~ !ll l'L' h anl ' r~h .If

References

-1

6

50

(, c:ns c:n~· . 1-I.T .. -\ cbtm . .I. A. Shi u'''-' Shi rl. On so me fundam e nta l

-\i n bin ckr. S.Ll. a nd Tikh nrn ir <'v: t. 1-.f-:. Tile mechanism wher eb y
_i,>ints arc i"urmc·d in u l t r :J su JJie·wdd i n~. lt'elding Production , 9
t 1962) , pp. 61-65 .

I I)

l 'ri sc ll , J ., I'I:Jd zc r, I'. I '. aml C lw1 ~ . U.l. Ult ra so nic welding of
md ah in v:tcuunl II th 'lTD H. Co nl'crcn cc held at the Uni ve rsity
" f \I:Jn chc"cr. 14-1 8 Sc't'i .. ( 197 0 ). Pc r ~a m o n Press, (197 0) .

I!

Sil in . I .. L .. Kuznct sn v. V. A . cr nd S,·su lin . G.\·. The ultrasoni c
\\· ,· ldin~ r>f crlu rn iniu m a nd its :til, ,-, _ li'cldinu p;·,xfuct ion 3
(l 960 ). pp. l 9-25.
.
,,
,

\\'ca re , N.E., Ant o nuvi ch . .1.:\. and :\ l unr uL', ICE . Fundamen ta l
st udies o f ultra s<~ nic 1\'C ldin~ . lt'd ding .lrm mal. 39, (1960),
PI' · 331-341.

I~

B.t l tndi n . C. F. :tncl Sil1i n . 1.. 1.. !'he• r~>k ,, 1- fr ictio n in ultra sonic
1\"c-ld ing l ;ves t ycJ ,-\\i SSSR . OT :\ . .11<-ra//urgl' en d ji1el, 6, (19 60).

I_;

IJ.,,Lrrhllll . ( .. 1 . .Jncl Sill 111. l...L. \k r!J, ,d, r,, ,. ubr ain ing stea d y
conditio ns in th e cd trctSillli c 1\'c• l clin ~ , >I JllC ia h. l\'c/ding
/l ·o,/uctio n. 12. (l96l).pp. 1·9 .

J" ne.s . .1. 13 ., \Jar,> pis. :\ .. l"h o n1 as . .I. G. an d Ba ncr o ft , D. Phenot nc·no lu ~ i cal cunsidcratiun s in ultraso nic w c l clin~, hie/ding
.lo umal. 40. (1961). pp. 3- 19.

l '~"• •bkrn s in ultr,Json ic weld in ~ r~f d i'S ir ni Ltr nwuls . Weldi11g
.fuum al. 46 . (1 967 ). pp . 145-153.

l -1

O l's han skii. N . A . Th e fortnat ion of ;oints in the ultrasonic
1\·ddi n:,: of meta ls. Auromaric J~'elding . 14, (1 96 1), No . 3,
pp. 1-8 .

m..,d .r \1 .. Shin. S.. \ liycr_c! i, .\1. a nd \Li tsuda . H. Joint m echani, tn ,,; ul traso ni c \\·e lcli n_c!. Tr a ns"uiuns o f th e hpa nese Inst i·
lu te ut ,\ lda ls, 4 , (1963) , pp. 250· 25 6.

15

Ri ch ter, H. Ubcr untcr suchun~c n vo n Vo rgangc n beim Verbinden
mcta.llische r We rksto ffe dur ch UltraschaJI. Sclnveissen und
Schneiden. 22. Heft 2, (19 70), p p. 70 -73.

Ginzburg. S.K., \litskevi clt , A.~·l. and Nosov . Y u.G. Formati on
of th e jo int in ultrason ic welclin)! . IJ'c/din !( Prn ,Juct ion 14 3
( I 96 7l. pp 83 -R7 .
,
'
,

16

Joshi . K.C. Th e fo rt m t ion of ul t rchll!li ,- bun ds b ~rwee n metal s,

Ul traso nics Internat io nal 1973 Conference Pro ceedings.

2.3

Joint formation in ultrasonic welding compared with fretting phenomena for aluminium

Welding Journal, 51, (1971), pp. 840-848 .

l7 Gufel'd, I.L. and Matveyeva, M.I. Development of the joint in
the ultrasonic welding of metals. Physics of metals and metallography,_l1, 4, (1964 ), pp. 141-143 .
18 Stemmer, R. Das iiltraschallschweissen dunner Bleche und
Folien, ETZ-B Elektrotechnische Zeitschrift, Ausgabe B, 20, 5,
(1968), pp. 101-104.
19 Heymann, E., and Pusch, G. Beitrag zur Klii rung der Rolle der
Rekristallisation bei der Verbindungsbildung beim Ultraschallschweissen. Schweisstechnik, 19, 2, (1969), pp. 542-545.
20 Kashiwabura, M., Hattori, S., Aoki, T. and Saito, Y. Defor·
mation characteristics and bonding process of fine aluminium
wire in ultrasonic bonding. Review of the Electrical Communication Laboratories, 1·8, (1971), pp. 791-797 .
21

Semenov, A.P. The phenomenon of seizure and its investigations,
Wear, 4, (1961), pp.l-9.

141, (1933), p. 233.
27

Hurricks, P.l. The mechanism of fretting, Wear, 15, (1970),
pp. 389-409.

28

Bethume, B. and Waterhouse, R.B. Adhesion of metal surfaces
under fretting corrosion, Pt. I. Wear, 12, (1968), pp. 289-296.

29 Godfrey, D. and Bailey, J.M. Early stages of fretting in copper,
iron and steel. Lubricating Engineering, 10, (1954), p. 155.
30 Hulst, A.P. A family of high power transducers. Paper presented at Ultrasonics International1973 Conference Proceedings, p. 285 .
31

Rykalin, N.N., Kusnetsov, W.A. and Sillin, L.L. Uber die
Relativbewegung beim Ultraschallschweissen von Metallen.
Bericht der Sowjetischen Delegation vor der Arbeitsgemeinschaft ,
Ultraschallschweissen, im RGW, (1967).

32

Dippe, W. Beitrag zu den Grundlagen des Ultraschallschweissens
von Metallen, Dissertation Magdeburg, (1971).

22 Beyer, W. Verbindungsbildung beim ultraschallsch weissen von
metallen. Schweisstechnik, 1.9, 1, (1969), pp. 16-20.

Discussion

23 Kulemin, A.B. and Mitskevich, A.M. Diffusion in metals under
the influence of ultrasound. Seventh International Congress on
Acoustics, Budapest, (24R62) , (1971), p. 245 .

H. FROST (USA) wanted to know whether the plastic
deformation in the aluminium sheets occurred by means of
actual liquid flow in a very localized region.

24 Campbell, W.E., Fretting. In: Boundary Lubrication, an appraisal of World Literature, Ed. Ling, K. pp. 119-131. ASME Research
Committee on Lubrication, (1969).

J.L. HARTHOORN did not know what the exact mechanisn"---of the plastic deformation was.

25

Thomlinson, G.A. The rusting of steel surfaces in contact.
Proceedings of th e Roy al Society of London, Series Al15,
(1927), p. 4 72.

26 Thomlinson, G.A. An investigation of fretting corrosion.
Proceedings of th e Institute of Mechanical Engineers (London),

B.S. HOCKENHULL (UK) suggested that on aluminium one
had a natural oxide film of about SON thick. The coherent
layer had to be broken down before' metal to metal'
contact was achieved on the bonding surfaces and this required
plastic deformation of the substrate .

Ultrasonics International 1973 Conference Proceedings

51


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