Tactile safety
May 1st 2007 Tactile safety is all arounf us says Barry Goodwin,
Leuze Mayser but we have to extra vigilant in
industrial safety situations
It will come as no surprise, that, as we
go about our lives, we all experience
the benefits of Tactile Safety without
noticing it - the lift door, bus and train
doors, revolving doors – all could have
tactile contact technology embedded in a
Safe Edge stopping us from becoming
trapped or dragged – it puts safety right at
the point of danger. When we enter the
field of industrial safety, the same principle
applies, but in this case the Safe Edge and
associated control are developed to a
higher standard, as severe injury, or even
a fatality, may result if personnel are not
protected from the hazards of dangerous
machinery.
The most widely used and proven
concept for Tactile Safety is the Safe
Edge, which comprises a tough resilient
rubber profile housing and a switching
sensor; when external pressure is applied
to the profile the sensor is tripped, thus
initiating a stop signal.
The very latest designs in this style
utilise a combination of highly sensitive
mechanical/electronic technology within a
profile allowing even small fingers or
clothing caught in the closing edge to be
detected, a signal is triggered and the
relevant action taken immediately.
Whilst the principle has remained
unchanged for many years, companies
like Leuze Mayser have extended the
functionality with the introduction of an ASi
Bus capability. It has enabled Leuze
Mayser to integrate tactile safety onto a
bus system with a series of other individual
safety devices to one safety module
allowing the simple adding or removal of
devices within the fieldbus circuit. The Asi
safety bus allows many individual devices
such as safe edges, emergency stop
switches, safety-interlocking devices,
safety light curtains, grids and safety
scanners all to be supported on a single
cable without jeopardising safety integrity;
the system also allows non-safety devices
to be connected on the same network.
Tactile form
The versatility and diversity of tactile safety
systems has allowed the creation of
pressure sensitive safety MATS, and a
much more versatile device in the form of
a safety BUMPER which can be shaped to
suit a particular application, however, the
most widely used tactile safety device is
the SAFE EDGE.
MATS – basically a pressure sensitive
mat system that can be shaped to suit
most requirements and is ideal for
placement in front of CNC punch
machines, around robot stations, transfer
lines, loading ramps, etc., offering up to a
safety category 3 protection for hazardous
areas. Mayser safety mats are offered with
various anti-slip rubber toppings, to suit
the application, and come with a range of
aluminium ramp edgings and fixings to
avoid the danger of tripping.
BUMPERS – a large impact cushion
made of soft foam with a suitable skin and
incorporating a switching element. The
soft foam construction prevents injuries to
personnel and damage to property until a
safe standstill is achieved. Indentation of
the foam profile causing the switching
element to activate, calling a halt to further
movement of the devices – Die Carts,
AGV's, shuttle cars, etc.
SAFEY EDGES - from lift platforms to
machine doors, from sliding shelves to
rollout gates - slight pressure is sufficient to
avert injury, the closed circuit principle
reliably protecting personnel from potentially
dangerous automatic movements. They are
manufactured to any length and can be
further customised to include angles, with or
without dead zones, etc.
A non-safety version of Safe Edges can
be found in County Courts, Police
interview rooms – placed around the wall
like a dado rail they provide simple, push
anywhere to actuate, alarm.
Sticking with the contact-style safe
edges, miniature versions have evolved
expanding their applications into the
automobile industry to prevent human
body-parts being trapped during closure of
electronic windows, the furniture industry
with its rise and recline chairs, adjustable
powered tables and other powered aids
for the disabled.
New tactile innovation
A recent innovation has been an optical
style safety edge whereby deformation of
the rubber profile interrupts an optical
beam, causing a stop signal. As a new
development the operating concept does
not have a strong proven track recorded
and must be viewed with caution, although
long-term it will probably offer a viable
alternative to contact switches and may
open new areas of application. More articles from Leuze Mayser Electronic Limited: | 
