Efficient Plant February 2018 - 24
feature | human/machine safety
technologies offer safer,
more operator- and
than earlier approaches.
PRESS BRAKES ARE unforgiving machines, and a frequent source of workplace
amputations of hands, fingers and arms. Statistics from the United States Department
of Labor (dol.gov, Washington) indicate
an average of 368 instances of amputations
annually from press-brake accidents. And
these are only the reported accidents.
Press brakes have a long history of productivity and danger. Hammers were the
tool of choice for any blacksmith until 1784.
That was when Scottish inventor James
Watt came up with concept of the "steam
The building of the first steam hammer in
1840 marked a turning a turning point for
manufacturing with steel. The downside of
this industrialization, though, was safety:
it was largely disregarded in the rush to
use labor-saving machines and processes.
Developments of press brakes and other
machinery occurred within a legal and
regulatory climate that diminished employer's interest in safety. In the process,
while highly effective production methods
became commonplace, for various reasons
they often were unsafe. Manufacturing
operations have come a long way since then
in terms of productivity and safety.
Older press brakes, i.e., those built prior
to 1985, were mechanical or flywheel types.
Stopping times were long, making modern
safeguarding techniques such as light curtains impractical. After 1985, press brakes
were hydraulic, allowing a wider variety of
safeguarding options with faster stopping
times. Still, regardless of their age, press
brakes present a unique set of dangers.
The primary safety concerns with press
brakes involve access to the point of
operation at the front of the machine and
reaching around the safety device to get
to the point of operation at the ends of
the machine. Pinch points and hazardous
motion created by the back-gauge system
are also problematic. But the dangers don't
However well intentioned, machine
fabricators often employ lower cost, used, or
refurbished press brakes that can make the
primary controls and/or condition of the
machine and safety system suspect. Because