Automation Canada - Machine Safety - 24

having the proper weld table or fixture is key. Most parts welded with
cobots tend to be lower volume, high variety parts. Fixturing for a cobot
is oſten achieved by means of an existing weld table and clamps. New
fixturing soſtware, like Camtec, offers manufacturers a cost-effective
way to produce a stable fixture that is well-suited for collaborative
welding.
Note: collaborative robots currently do not offer external axes
compatibility, so applications requiring the use of specific positioners
for coordinated motion or a robot track need to be mitigated by
fencing, light curtains or other means. While items such as fencing may
result in additional upfront cost (sometimes 20% of a work cell's overall
cost), it is oſten the simplest and best way to mitigate common risks.
If the use of safety fencing is inevitable - due to cycle time
requirements or part turning specifications - a positioner may be in
order. If so, positioner size can make a difference. For example, a Ferris
wheel RM2 positioner with a two-station design is more space efficient
than an H-frame turn table, optimizing floorspace utilization. The right
positioner can also go a long way to meeting strategic company goals
for the number of welded inches per minute (ipm).
FUME EXTRACTION
Whether they are close to the process or not, protecting human
workers from harmful fumes throughout the facility is of the utmost
importance and oſten required by local safety regulations. Widely used
for manual weld processes, ambient air extraction systems and hood
fume collection systems can still be used for a variety of robotic welding
applications today. However, each demands a unique set of criteria that
may hinder certain collaborative processes.
For example, ambient air filtration systems seek to filter all the air
within a facility. For large facilities separated by columns, walls, or even
large machinery, this can present a huge risk - as these objects can trap
air, causing " dead zones " or pockets of poorly filtered air. While highly
effective for the right application, hood fume collection systems also
CANADIAN AUTOMATION
present risks under certain circumstances. For example, if a cobot is
being rolled-up to a large workpiece that requires placement via an
overhead gantry, a hood is typically too small to accommodate the
filtration process needed. Add in other factors like the upfront capital
required or monthly energy consumption costs, and these systems are
not always ideal, especially for collaborative weld jobs.
Enter the concept of source capture robotic fume extraction. To
provide customers with an easier to implement and more economical
solution, innovative weld equipment suppliers now offer fume capture
at the source. Most beneficial for these systems is their ability to keep up
with the higher duty cycles and throughput requirements of robotic
welding. These options work at the torch level and feature filtration
packs that can " ride along " with collaborative robots. The plug and play
ability of source capture devices is especially helpful for welding large
parts for heavy fabrication, as well as on-demand supplemental
welding.
ARC FLASH
As in traditional welding environments, manual welders should
mitigate arc flash and UV exposure via personal protective equipment
(PPE). Safety arc flash curtains or other barriers should also be put in
place, when needed, to protect bystanders.
ADDITIONAL SAFETY
Depending on application requirements, additional safety measures
may help. An interfaced stack light mounted on the robot cart or nearby
can assist to visually confirm the status of a robot, as well as provide
sufficient warning to those close to the work area that the robot is about
to weld. This allows workers and bystanders plenty of time to look away
from the arc or get out of the way. Tone-emitting or " talking " versions
that give audible commands are also available.
An extra mode of collaboration to increase speed and mitigate risk, an
area scanner may also be used to make sure no one is immediately
VOLUME 4, ISSUE 2
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Automation Canada - Machine Safety

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