Efficient Plant February 2018 - 25
feature | human/machine safety
Left. Laser AOPD systems allow operators to work within close proximity (15 mm) of the point
of hazard. Photo courtesy of Laser Safe
personnel in such enterprises may not
have safeguarding competency, serious
shortcomings can be overlooked or
ignored. Plus, original equipment manufacturers (OEMs) generally consider the
point-of-operation aspect of the pressbrake safety system to be the end-user's
responsibility. The end user, in turn, may
incorrectly assume that the machinery
arrived on-site in full operating condition for commissioning. Lastly, press
brakes have always been operator-intensive technologies-sometimes involving
multiple operators. Unfortunately, operator behavior is not always predictable.
That's why it is good practice to make
one operator the leader of the crew.
Training should be completed before
any employee or operator is allowed to
work near the press brake, and the employer should maintain accurate records
of all training. Employees should also be
encouraged to report press-brake hazards
and make suggestions related to safety.
Refresher training should be conducted
It is also good practice to develop and
enforce a written safety program, one
that incorporates guidelines for operating all machinery and performing tasks.
Employees should be given a copy and
provided training that emphasizes safe
operating procedures, limitations of
equipment, use of guards, and hazard
recognition and control. Employers
should monitor employee compliance
with all policies.
There are two sources of press-brake regulations: OSHA and ANSI. Of the two,
ANSI is considered the more specific and
OSHA's machinery and machine
guarding regulations (29 CFR 1910
Subpart O) require one or more
guarding methods to protect employees from exposure to hazardous
machine energy during the operation
of press brakes. There isn't a great deal
of detail to the OSHA regulations, so
fabricators in search of answers would
be better served by turning to ANSI
B11.3-2012, which covers safeguarding
of power presses. The B11.3 adopted EN
12622 (European standard), giving it
even more specific instructions to follow
and minimizing any vague, gray areas.
ANSI B11.3 is the only safety-system
standard specifically applicable to power
press brakes used in America, and it
excludes mechanical power presses,
hydraulic power presses, hand brakes,
tangent benders, apron brakes, and
other similar types of metal-bending
machines. It discusses hazards associated with the point of operation at length
and identifies alternative guards and
devices,including, for example, the "close
proximity point of operation AOPD"
safeguarding devices, discussed later in
this article, and a means of safeguarding
referred to as "Safe Speed."
Today, there several ways to safeguard a
press brake, some better than others. All
have advantages and drawbacks.
The most basic type of safeguarding
is a fixed and interlocked barrier guard
coupled with two hand controls. This is
not a functional solution for fabricators,
as a work piece held by hand in close
proximity to the point of operation
during the braking process can
Fig. 1. The main difference between laser AOPD and
light-curtain systems is that the first protects the
point of hazard itself and the second restricts operator
access to the point of hazard.
THE 'GOLDEN RULES'
OF PRESS-BRAKE USE
Basic safety procedures bear
repeating. The "golden rules" of
press-brake use can save body
parts and lives:
Keep work area clean, orderly, and
free of oil, grease, or scrap.
Use work supports, mechanical assists, or helpers when loading and
unloading parts or heavy sheets.
Wear PPE, i.e., gloves, goggles:
never wear loose clothing, wristwatches, rings, bracelets, and other items, when operating machinery to avoid being dragged into
the danger area.
Never leave machine running
Keep hands away from all moving
items (ram, work pieces). Avoid
trip hazards with foot switch
Always lockout/tagout (LO/TO)
equipment before performing
maintenance, no matter how small
Never use damaged dies.
Never attempt to tamper with
wiring or bypass safety control.
When finished, position ram at
bottom of stroke and LO/TO.