Advanced Welding Processes: Technologies and Process Control

Welding automation and robotics 223
11.4 Dedicated and special-purpose automation
11.4.1 Dedicated automation
Dedicated automation involves the design of a special welding system for a
particular application and the resultant equipment may not be adaptable to
changes in joint or component design. This type of automation is usually
only justified for large production volumes of components with an extended
design life.
Dedicated automation has traditionally been used for automotive components
such as road wheels and exhaust systems with a wide range of welding
processes including resistance spot, GTAW and GMAW.
The welding head is often only a single station in a multi-station automation
system, which prepares the component for welding and also carries out
finishing operations; in such cases a ‘carousel’ design with a single load–
unload station is often used. Dedicated welding systems have also been
employed, where lower production volumes and shorter product life cycles
are envisaged, but the welding environment is particularly hostile or the
quality of the end product is of primary importance. Examples of this type of
application are to be found in the nuclear industry, both in processing of
radioactive materials and the construction of critical fabrications. An example
of the type of equipment used for this latter application [266] was used for
GTA welding of advanced gas-cooled reactor (AGR) standpipe joints on the
Heysham II and Torness (UK) power station projects. The use of costly
dedicated automation with a sophisticated power source 1 and control system
was justified on the grounds of the unacceptability of defects and the
repeatability of performance.
The need to purpose design the dedicated systems around a specific
component usually makes the cost of such equipment high and many dedicated
automation applications are now being tackled using the modular or the
robotic approach.
11.4.2 Special-purpose automation systems
Special-purpose automation has been developed for particular applications
where similar joints are to be made on a range of component sizes. Some
examples are simple seam welders, orbital welding systems and the GMAW
stitch welder.
1 The power source used was a transistor series regulator with facilities for pulsed GTAW,
programmed touch starting and arc length control. The welding head was also equipped
with a vision system for remote monitoring of the weld area.