Real-Time Ultrasonic Evaluation of the Aluminum Resistance ......Real-Time Ultrasonic Evaluation of...

Real-Time Ultrasonic Evaluation of the Aluminum

Resistance Spot Welding ProcessW. Perez Regalado, A. Chertov, R. Gr. Maev

“Real-Time Ultrasonic Evaluation

of the Aluminum Resistance

Spot Welding Process”

Waldo J. Perez Regalado

Dr. Roman Gr. Maev

Dr. Andrey Chertov

Institute for Diagnostic Imaging Research

University of Windsor



Contents:

2

•Spot Welding Process

•Destructive Testing

•Offline NDT

•Inline NDT

•Real-Time Weld Analyzer

•Aluminum Inline RSW Monitoring

•Conclusions



Spot Welding Process

3

[1] www.nsrw.com



Spot Welding Process

4

Spot welding is

highly

automated

today

Regular

vehicle

contains

3000-4000

spot welds



Destructive Testing

55

5

Peel test Cross-section

Cons: Selective testing;

Time consuming;

Labour intensive.

More than 99% of the parts are never

checked. For this reason, at the design

stage, additional spot welds are introduced

into the assembly process.



Offline NDT

6

The part to be inspected should be pulled

out from the production line and scanned

manually



Inline NDT

7

Pulser/RecieverWelding

Machine

PC



Inline NDT

8

0 50 100 150 200 250-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15Pressure Signal p(t)

Time x 1/60 Seconds

Am

plit

ude

0 20 40 60 80 100 120 140 160-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15Pressure Signal p(t)

Time x 1/60 Seconds

Am

plit

ude



Inline NDT

99

PC

1

2

3

4

5

Incident wave

Copper Electrode

Steel Plate 1

Steel Plate 2

Copper Electrode

Molten

Nugget

Current ON

Arr

iva

l T

ime 1

2

34

5

Welding time

Ultrasonic probe

built into

electrode*

** Ultrasonic In-Process Monitoring And Feedback Of Resistance Spot Weld Quality.

Patent application by R.Gr. Maev and A.M. Chertov. Attorney Docket No. 706940US1

**

Arrival time

Am

plit

ud

e 1

2 34

5



Real-Time Integrated Weld Analyzer

10

Metals:

•Mild steel

•High strength steel

•Dual phase steel

Coatings:

•Bare

•Galvanneal

•Galvanized

www.tessonics.com




11

d1

d2

d3

d1

d2

d3

d1

d2

d3

d1

d2

d3

d1

d2

d3

d1

d2

d3

d1

d2

d3

Real Acoustic Image Pattern Weld geometry




12

Stick Weld (0.0 mm) Good Weld (5.4 mm)

Steel Plate 1 Steel Plate 1

Steel Plate 2 Steel Plate 2

Time, ms

0 150 300 450 600 0 150 300 450 600

Welding current

Time, ms

Welding current




13

Welding Time x 2 ms

Tim

e O

f F

ligh

t x

15

ns

50 100 150 200 250

50

100

150

200

250

Nugget Penetration

Estimate nugget

diameter with

Maximum TOF



Aluminum RSW Monitoring

14

Steel B-Scan

Welding Time x 2 ms

Tim

e O

f F

light

x 1

5 n

s

50 100 150 200 250

50

100

150

200

250

Welding Time x 2 ms

Tim

e O

f F

light

x 1

5 n

s

50 100 150 200 250

50

100

150

200

250

Aluminum B-Scan




15

Q= I2RtAluminum Steel

Weld Time 60 ms 200 ms

Current 21 kA 9 kA

Table 2 - Welding Schedules for 1 mm plates

Steel B-Scan

Welding Time x 2 ms

Tim

e O

f F

light

x 1

5 n

s

50 100 150 200 250

50

100

150

200

250

Welding Time x 2 ms

Tim

e O

f F

light

x 1

5 n

s

50 100 150 200 250

50

100

150

200

250

Aluminum B-Scan




16

LPT Interface

DSP based

Electromechanical multiplexer (1 ms switch time )

66 MHz 10 bit ADC

B-Scan storage of 28 KB

USB2.0 interface

FPGA based

Electronic multiplexer (8 us switch time)

133 MHz 12 bit ADC

B-Scan storage of 2 MB

Welding Time x 2 ms

Tim

e O

f F

light

x 1

5 n

s

50 100 150 200 250

50

100

150

200

250

Welding Time x 0.6 ms

Tim

e O

f F

light

x 7

.5 n

s

50 100 150 200 250 300

50

100

150

200

250

300




17


Tim

e O

f F

light

x 7

.5 n

s

50 100 150 200 250

50

100

150

200

250


Tim

e O

f F

light

x 7

.5 n

s

50 100 150 200 250

50

100

150

200

250


Tim

e O

f F

light

x 7

.5 n

s

50 100 150 200 250

50

100

150

200

250

After 10 welds After 50 welds After 100 welds




18

Thickness varies depending on the storing of the material but goes

from 5 nm - 2 µm

Property Value

Density 3.95-4.1 g/cm3

Melting Point 2072 °C

Electrical Resistivity 1x1014 Ω·cm

Thermal Conductivity 5.43 W/m/K

Thermal Expansion 10–6/°C

Aluminum

Aluminum

Oxide




19

[2] Muhammad Rashid “Some Influences of Tribology in Resistance Spot

Welding of Aluminum Alloys” Ph.D Thesis University of Waterloo

A) Metal - Metal

B) Metal – Oxide

C) Air Gap

D) Oxide - Oxide




20

Electrode Pitting and Alloying

[3] I. Lum, S. Fukumoto, E. Biro, D.R. Boomer, and Y. Zhou, “Electrode Pitting in Resistance Spot

Welding of Aluminum” 2004 Metallurgical and Materials transaction A (35A). pp. 217–225.

A) CuAl2B) C) AlCu

D) CuAl2E) Cu9Al4




21

[4] S.J. Dong and Y. Zhou “Effects of TiC Composite Coating on Electrode

Degradation” Metallurgical and Materials Transactions A 2007




22

0

1

2

3

4

5

6

0 100 200 300 400 500 600 700 800

Nu

gg

et

Dia

me

ter

( m

m)

Weld Number

Cap Degradation

A

C




23

Cap Degradation

The Peltier Effect

A

C




24

Transducer Installation


Tim

e O

f F

light

x 1

5 n

s

50 100 150 200 250 300

50

100

150

200

250

300

After 0 WeldsWelding Time x 0.8 ms

Tim

e O

f F

light

x 1

5 n

s

50 100 150 200 250 300

50

100

150

200

250

300


Tim

e O

f F

light

x 1

5 n

s

50 100 150 200 250 300

50

100

150

200

250

300

After 200 Welds


Tim

e O

f F

light

x 1

5 n

s

50 100 150 200 250 300

50

100

150

200

250

300


Tim

e O

f F

light

x 1

5 n

s

50 100 150 200 250 300

50

100

150

200

250

300


Tim

e O

f F

light

x 1

5 n

s

50 100 150 200 250 300

50

100

150

200

250

300

After 500 Welds

Industry Average:

Cap dressing every 100 welds




25

Welding Time x 1 ms

Tim

e O

f Flig

ht x 7

.5 n

s

50 100 150 200 250 300 350

50

100

150

200

250

300

1 mm

Plate 1 ( 0.9 mm )

Plate 2 ( 1.9 mm )

Welding Time x 1 ms

Tim

e O

f Flig

ht x 7

.5 n

s

50 100 150 200 250 300 350

50

100

150

200

250

300

1 mm




26

c t

RF

RB

Nugget Diameter Estimation

R² = 0,8044

0

1

2

3

4

5

6

7

90 95 100 105 110 115 120

Nu

gg

et

Dia

me

ter

( m

m )

H ( uS )



Conclusions

27

• Inline ultrasonic monitoring of the aluminum spot welding process is possible, however

faster acquisition hardware is required.

• The aluminum oxide formed on the substrate surface, causes rapid electrode deterioration.

The Peltier effect increases the deterioration on the anode electrode, therefore the

ultrasonic probe should be installed on the cathode side.

• Time of flight is not a good indicator of nugget size on aluminum. A new metric that takes

into consideration the time when the maximum temperature was achieved was proposed

showing good correlation with nugget diameter.

• Liquid penetration can be measured from the ultrasonic B-Scans.



QUESTIONS ???

More details:

[email protected]

http://www.idirresearch.com/

http://www.tessonics.com/

28

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