FORACAM: A VERY PRECISE IMAGING METHOD FOR THERMAL METAL PROPERTIES CHARACTERIZATION ANDFLAW DETECTION

EDEVIS GMBH

STUTTGART

GERMANY

OTvis Optical excited Lockin-Thermography

UTvis Ultrasound Thermography

PTvis Pulse Thermography

ITvis Inductive excited Thermography

Software DisplayIMG 6Image processing and excitation controller / real-time

EDEVIS

ForaCAM Photothermal radiometry

Infr

are

d c

ame

ras

Co

ole

dFP

A a

nd

Mic

ro-b

olo

met

er

SHEAROvis Laser-Shearography

PRODUCTS

LTvis Laser Thermography

LITe Electro-Testing

EDEVIS

APPLICATIONS

Measurement of hardness /hardness profile

► Time-consuming

► Destructive test

State of the art: indentation (Rockwell, Vickers, …)

EDEVIS

APPLICATIONS

Measurement of carbonized depth

microscopy

State of the art: metallography ► Time-consuming

► Destructive test

embedding, milling, polishing, etching

sampling

EDEVIS

APPLICATIONS

Detection of grinding burn

► Time-consuming

► Destructive test

sampling

microscopy

embedding, milling, polishing, etching

State of the art: metallography

EDEVIS

TASK: INCREASE COST-EFFICIENCY

► Non-destructive test: test object can still be used

► Avoid sample preparation: save time to notice weak hardening process muchearlier

sampling

microscopy

embedding, milling, polishing, etching

► Inline measurements: 100% inspection instead of samples, avoidrejection of whole batches

EDEVIS

SOLUTION: FORATHERM

PHOTOTHERMAL RADIOMETRY

Determination / detection of► layer thicknesses► case hardness depths► nitriding depths► hardness profiles► porosity contents► grinding burn► hidden corrosion

EDEVIS

FORATHERM: EXAMPLES

Depth [mm]

Ha

rdn

ess

HV

0.2

1000

900

800

700

600

500

400

3000,0 0,5 1,0 1,5 2,0 2,5 3,0

conventionalForatherm

f 0,5 [Hz 0,5]

Ph

ase

co

ntra

st[°

]

250 µm257 µm500 µm

1028 µm

514 µm1000 µm

3000 µm

30

20

10

0

-10

-20

-30

-40

-50300250200150100500

Non-contact determination of hardnessprofile(after calibration with reference body)

Non-contact determination of Invarlayer thickness on silicon substrate

EDEVIS

FORATHERM: EXAMPLES WITH SCANNING

Welding seam annealed / not annleaded Grinding burn

with grinding burnwithout grinding burn

EDEVIS

FORATHERM PHOTOTHERMAL RADIOMETRY

► Non-contact► Non-destructive► Inline-testing is possible► Faster than materialographic

analysis

Advantages Drawbacks

► Detectorsize 1 Pixel:Imaging requires time consuming scanning of sample or sensor head

EDEVIS

1 PIXEL IS ENOUGH?

Why not using an infrared camera?

► Metals have a high thermal diffusivity:Very high frame rates needed

► Layers like grinding burn are verythin:Extremely high frame ratesneeded

► Signals levels are very small:Perfect temporal synchronization needed

► FLIR X8500sc, 180Hz

► Subwindowing✓

► edevis signalgenerator ESG

► edevis softwareDisplayIMG

✓

► FLIR X6900sc, 1003Hz

► Subwindowing► Subsampling

✓

EDEVIS

FORACAM SETUP

Collinear setup of IR camera and excitation laser with dicroiticmirror

Advantages:► Measurement spot position independent from working distance► No geometrical constraints between camera & lens and laser

excitation

EDEVIS

FORACAM

Case hardened specimen, tested at different modulation frequencies

3 Hz 18 Hz 88 Hz

10 mm spot size: phase signal 1D heat flow -> lower phase contrast3 mm spot size: phase signal influenced by 3D heat flow -> higher phase contrast

due to lateral heat flux effects Spot size should be optimized For imaging, array of laser spots can be used

-15

-10

-5

0

5

10

15

20

0 5 10

phase c

ontr

ast

[°]

frequency0.5 [Hz0.5]

F4_HT_10mm

F6_HT_10mm

F8_HT_10mm

F4_HT_3mm

F6_HT_3mm

F8_HT_3mm10 mm laser spotsize

3 mm laser spotsize

EDEVIS

FORACAM CASE-HARDENING CHARACTERIZATION

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

0 1 2 3 4 5 6

Phase c

ontr

ast

[°]

frequency0,5 [Hz0,5]

F3 F4 F5 F6 F7 F8

Case hardening depths of 16MnCr5 samples between 0.3 and 2.0 mm

CHD:F3 0.3 mm F4 0.5 mmF5 0.8 mmF6 1.0 mmF7 1.3 mmF8 2.0 mm

Strong signal change -> CHD can be determined quantitatively (requirescalibration)

EDEVIS

FORACAM VS FORATHERM

Case hardening depths of 16MnCr5 samples between 0.3 and 2.0 mm

ForaTherm (1 pointdetector)

ForaCAM (focal plane arraydetector)

Ph

ase

con

tras

t[°

]

Ph

ase

con

tras

t[°

]

Frequency0.5

[Hz0.5]Frequency0.5

[Hz0.5]

ForaCAM is even more sensitive!

EDEVIS

FORACAM GRINDING BURN DETECTION

Collinear setup of IR camera and excitation laser with dicroiticmirror

Frame rate 900 HzSubwindow 160 x 160 pixelIFOV 125 µmMeasurement field 20 x 20 mm2

Laser power 200 W

EDEVIS

FORACAM GRINDING BURN DETECTION

10 Hz 39 Hz 82 Hz 150 Hz

225 Hz

23 Hz 65 Hz 205 Hz

405 Hz

905 Hz

Foracam Specimen 1 (measurement duration: 30s per image)

Foratherm Specimen 1 (scanned, measurement duration ca. 60min per image)

EDEVIS

FORACAM GRINDING BURN DETECTION

10 Hz 39 Hz 82 Hz 150 Hz

225 Hz

23 Hz 65 Hz 205 Hz

405 Hz

905 Hz

Foracam Specimen 2 (measurement duration: 30s per image)

Foratherm Specimen 2 (scanned, measurement duration ca. 20min per image)

EDEVIS

FORACAM SYSTEM COMPONENTS

Sensor head with dicroitand IR camera: Foracam

Synchronization: ESG

Laser: LTvis 250 NT

Software: DisplayImg

Optional: LTvis cabinet

SUMMARY

After a calibration, metallography can often be replaced

For one spot measurements Foratherm is suited perfectly

Imaging photothermal radiometry is now possible withhighspeed IR cameras and edevis hard- and software

Both methods reduce costs and increase reliability

Lab systems and industrial test stands availably

LOCKIN-THEMOGRAPHYFOR INVESTIGATION OF ELECTRONIC COMPONENTS

WHY LOCK-IN?

• Lock-In Thermography is well known and widely used in active thermography. Typical applications are non-destructive material testing and material characterization

• This powerful technique can help to see smallest temperature differences in electronic components with increased contrast and improved spatial resolution avoiding thermal undesired dissipation effects

• The technique can be combined with current FLIR cameras such as FLIR A655sc, FLIR A6750sc, or T1030sc with high speed interface.

SYSTEM CONFIGURATIONFLIR R&D Camera Standard Core i7 computer

Standard power supplyEdevis signal generator

and power switch

TEMPERATURE IMAGE

Dis

sip

ation H

ots

pots

Vo

lta

ge

regu

lato

r

D/A

co

nve

r

Resis

tor

DC

/DC

co

nve

rte

r

TEMPERATURE VS. LOCK-IN

Temperature image.

Overall temperature distribution is visible.

Lock-In Amplitude at 0,5 Hz.

Areas of local dissipation are highlighted

selectively.

TEMPERATURE VS. LOCK-IN

-0.2

-0.1

0

0.1

0.2

0.3

0 50 100 150 200 250 300

Profile

0

0.002

0.004

0.006

0.008

0 50 100 150 200 250 300

Profile

Temperature increase 4s after start of heating Lock-In Amplitude at 0,5 Hz.

Measured difference: 6mK

CONCLUSIONS

• Lockin technique can significantly increase system sensitivity

• Spatial resolution is increased as well due to reduction of thermal diffusion length

• Emissivity effects are suppressed

• Compatible to many existing cameras