Automation Canada - Machine Safety - 30

MACHINE SAFEGUARDING TECHNOLOGY
KEEP OPERATORS OUT OF A PINCH
ROCKFORD, IL, APRIL 25, 2022 - Pinching your finger in a door can
be painful but certainly not life threatening. Pinch point injuries
involving industrial machinery are another story, one that rarely has a
happy ending.
A pinch point is created when two objects come together and there is
a possibility that a person could be caught or injured when coming in
contact with that area. If any part of the worker's body, typically hands or
fingers, occupies that space during the pinching movement, there is a
high probability of injuries such as fractures, amputations, contusions,
lacerations or even death. Machinery parts move at high rates of speed,
making it difficult for an individual to pull free once caught.
Pinch-point injuries oſten occur as the result of workers who are not
properly trained or don't realize the dangers of machinery, or who take
shortcuts to get the work done more quickly, but end up injuring
themselves instead. Other common causes are:
* Loose clothing, hair or jewelry becoming entangled in rotating
parts, drawing fingers, feet and hands into a pinch point.
* Poor condition of equipment and lack of machine safeguarding
* Not wearing Personal Protective Equipment (PPE)
* Dropping or carelessly handling materials or suspended loads
* Placing hands where they can not be seen
* Not using the proper work procedures include LOTO
* Reaching into moving equipment and machinery to clear debris.
A pinch point injury can be the result of something as large as a
hydraulic press or as small as a pair of wire strippers. Of the thousands of
disabling accidents that happen on the job each year, one third of them
are hand injuries... and of those injuries approximately 80% are caused
by pinch points.
CANADIAN AUTOMATION
In any plant or machine shop, there are machines and activities that
can cause workers to be seriously injured by pinch points. Many of
these hazards are avoidable yet some are not. For these unavoidable
hazards, it's critical to protect workers with machine safeguarding, as
well as to keep them aware and alert of the hazards by providing
training and posting safety labels.
RIVETERS & WELDERS
For the purpose of this article we will be looking at " Good, Better,
Best " approaches to safeguarding two of those types of machines that
present unavoidable pinch point hazards - riveters and welders. It is
important to appreciate the magnitude of force between electrodes or
tips. Depending on the material thicknesses being spot welded, a
strong weld joint requires a forging pressure ranging from several
hundred to several thousand pounds. For example, a welding machine
with a ¼-in. electrode face set with 600 lb of electrode force will
develop 12,230 lb/in2. This can cause major crushing damage to the
operator's finger if caught at this pinch point.
Light curtains are not one of the solutions we will be looking at. Light
curtains are rarely practical with hand-fed welding or riveting since the
user's hands will normally be in the point of operation. Also, light
curtains cannot usually handle parts that have flanges that are in the
same area as the operator's hands.
GOOD: DROP-PROBE DEVICES
Drop-probes provide economical, simple to understand and use,
reliable protection for the operator. Drop-probe devices function by
allowing a sensing probe to drop by gravity around the
point-of-operation hazard of a riveter or welder prior to each intended
machine cycle. If the sensing probe encounters the operator's fingers
VOLUME 4, ISSUE 2
30
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