foracam: a very precise imaging method for …10 mm spot size: phase signal 1d heat flow -> lower...
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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