A non-obtrusive, pre-aligned, solid-state device has been developed to monitor the primary infrared emissions during laser welding. The weld monitor output is a 100-1000 mV signal that depends on the beam power and weld characteristics. The DC level of this signal is related to weld penetration, while AC portions of the output can be correlated with surface irregularities and part misalignment or contamination. Changes in DC behavior are also noted for both full and deep penetration welds. Full penetration welds are signified by an abrupt reduction in the weld monitor output. Bead on plate welds were made on steel, aluminum, and magnesium with both a CW CO2 laser and a pulsed Nd:YAG laser to explore the relationships between the weld characteristics and the weld monitor output.

Topics
Solid-state devices, Lasers, Chemical elements, Welding
1.
Chen
,
H. B.
,
Li
,
L.
,
Brookfield
,
D. J.
,
Williams
,
K.
, and
Steen
,
W. M.
 (
1991
). Laser process monitoring with dual wavelength sensors.
Proceedings of Laser
Institute of America (CALEO ’91)
,
Orlando, FL
.
1722
:
113
–
122
.
Google Scholar
 
2.
Bagger
,
C.
,
Miyamoto
,
I.
,
Olsen
,
F.
, and
Maruo
,
H.
 (
1991
). On-line control of the CO2 laser welding process.
Beam Technology Conference Proceedings
,
Karlsruhe
,
Germany
.
135
:
1
–
6
.
Google Scholar
 
3.
Olsen
,
F. O.
,
Jørgensen
,
H.
,
Bagger
,
C.
,
Kristensen
,
T.
, and
Gregersen
,
O.
 (
1992
). Recent investigations in sensories for adaptive control of laser cutting and welding.
Proceedings of LAMP 92
,
High Temperature Society of Japan
,
Nagoka, Japan
.
405
–
414
.
Google Scholar
 
4.
Chang
,
D. U.
 (
1994
).
Monitoring laser weld quality in real time. Induse Laser Rev
.
5.
Maischner
,
D.
,
Drenker
,
A.
,
Seidel
,
B.
,
Abels
,
P.
, and
Beyer
,
E.
 (
1991
).
Process control during laser beam welding
.
Proceedings of Laser Institute of America (CALEO ’91
),
Orlando, FL
.
1722
:
150
–
155
.
Google Scholar
 
6.
Mori
,
K.
, and
Miyamoto
,
I.
 (
1997
).
In-process monitoring of laser welding by the analysis of ripples in the plasma emission
.
Journal of Laser Applications.
9
:
155
–
159
.
https://doi.org/10.2351/1.4745455
Google Scholar
Crossref
Search ADS
 
7.
Nava-Rüdiger
, and
Houlot
,
M.
 (
1997
).
Integration of real time quality control systems in a welding process
.
Journal of Laser Applications.
9
:
95
–
102
.
https://doi.org/10.2351/1.4745449
Google Scholar
Crossref
Search ADS
 
8.
Leong
,
K. H.
 (
1997
). Low cost laser weld monitoring system.
Automotive Laser Applications Workshop 1997
,
University of Michigan
,
Novi, MI
.
Google Scholar
 
9.
Steen
,
W. M.
 (
1991
).
Laser Materials Processing
.
Springer Verlag
,
London
.
Google Scholar
Crossref
Search ADS
 
10.
Smithells
,
C. J.
,
Brandes
,
E. A.
, and
Brook
,
G.
 (
1991
).
Smithells ’ Metals Reference Book
.
Butterworths
,
Boston
.
Google Scholar
 
11.
Forsythe
,
W. E.
 (
1959
).
Smithsonian Physical Tables
.
Smithsonian Institution
,
Washington
.
Google Scholar
 
This content is only available via PDF.
© 1997 Laser Institute of America.
1997
Laser Institute of America
You do not currently have access to this content.