Page 18 - Workswell Catalogue

Application - Laser welding

17
SURFACE TEMPERATURE MONITORING DURING CONTOUR LASER

WELDING OF PLASTICS

Welding of plastic parts is now-
adays a very used technology
in the industry for permanent
joining parts together. There are
several types of plastic welding
technologies: hot body welding,
hot gas, friction and ultrasound
but also laser welding.

Laser beam welding is advan-
tageous for welding very small
and narrow plastic parts due to
the size of the laser beam. When
Automation
placing several laser beams side
by side we can create any shape
and size of the welded contour.
The laser beam passes through
a transparent part of the plastics
and stops at the base part. At this point, the joint begins to heat until the two parts are joined together. The process
needs to be monitored to maintain a constant and long-term weld quality.

SETTING OF THE ASSIGNMENT

One of the leading automotive companies, Xxxxx, focuses on innovative solutions for compression-ignition and
combustion engine support systems. In this case, the entire contour of the weld needed to be monitored when
welding plastic parts of the DC motor case to reach the desired temperature and thereby to ensure that the
weld is tight. The objective is, among other things, to achieve homogeneity throughout the weld contour to de-
tect a damaged laser beam in the welding head and therefore to prevent the production of other non-compli-
ant pieces. The data from each measurement were sent to the data archiving database for each specific piece.

SOLUTION OF THE ASSIGNMENT
To address the application, the ThermoInspector thermal imaging system was used, which is primarily intended
for the applications monitoring production processes, monitoring temperature stability and homogeneity during
processes, input – output temperature monitoring, etc., and where up to 4 WIC thermal imaging cameras may be
connected simultaneously.

In this particular case, due to the size and shape of the welded parts, two WIC thermal imaging cameras were used
which are connected to the ThermoInspector control unit via the Ethernet cable. The thermal imaging cameras
were placed on the static holders facing each other, each on one side
of the welded piece to cover the entire contour of the weld.
The system was configured to the Fixed Time Measurement Mode,
which means that the camera monitors the respective areas in the
image (ROI) for a fixed number of pictures after the trigger signal, in
this case it is only one picture. The Trigger signal was brought to the
ThermoInspector system from the control PLC and it is activated when
the welding head starts to weld.