Amy Defayette
Product Marketing Manager
VarioFlow, Bosch Rexroth Corp.
Buchanan, Mich.
At one time conveyors were
fabricated in permanent
configurations. Structural
members were usually
welded from milled or stainless
steel, or aluminum. Newer modular
conveyors, however, use extruded aluminum
framing that bolts together. These
modular frames let manufacturers divide
the components (drives, returns, straight
and curved sections, supports) into modules
that can be mixed and matched to
meet changing needs. The concept is analogous
to the curved and straight tracks of a
model-train set.
Modular chain conveyors use plastic
chain, which is also modular. The chain
is usually made from links that mix and
match to fit the application. For instance, a
cleated link at every fifth link could move
items along an incline as steep as 90°. In
the future, cleated links at every tenth position,
or perhaps a taller cleat, will better
serve the purpose.
Conventional conveyors are satisfactory
for a single application but they don’t
easily accommodate field changes. It is not
uncommon for the layout of a packaging
line to change repeatedly until the moment
it goes on line.
Modular conveyors give engineers an out
when some detail is overlooked, like discovering
a layout violates OSHA regulations
because it’s 2 in. too close to the eyewash
station. Or when the shifting of a primary
machine suddenly makes a carefully laid out,
welded conveyor unworkable.
Modular conveyors have been around
since the early 1980s, and Robert Bosch
GmbH was one of the first companies to experiment with extruded aluminum
for the frame, thus pioneering
the concept of flexible automation.
Initially, these conveyors
transported heavy-duty parts. But
standard modules that combine
to make custom configurations
caught on quickly. Packaging applications
were introduced in the
early 1990s.
Modular conveyors continue to
evolve, mostly by the addition of
new modules or adaptations for
specific applications. For example,
food manufacturers prefer stainless-
steel conveyors that open in
the center for accessibility. Special
chain links with soft flocking to
protect cardboard packages from
scratching are another innovation.
The use of modular conveyors
in packaging lines is growing
rapidly because the marketplace
demands flexibility. Remember
when mayonnaise only came in
wide-mouth glass jars? Now you
can buy mayonnaise in rectangular plastic
containers that fit better in the refrigerator.
The local supermarket testifies to the
variety of packaging for foods, beverages,
and cleaning supplies. Specialty packaging
has become a major weapon in the battle
for grocery dollars.
Every product reacts differently as it
moves along a conveyor. Center of gravity,
weight, friction, and a host of other factors
mean the best approach for one item may
not work for another. Reconfiguration of
modular guide rails can prevent product tipping.
But what’s making new conveyors better
is the ability to bend tighter and tighter
curves so accumulators and buffers take up
less floor space. Many of today’s accumulating
systems are simply tight-curve conveyors
stacked one on top of the other.
In most packaging applications, adjustable
guide rails are necessary for handling
frequent adjustments. These guide-rail
systems continue to offer more flexibility.
And so-called T-slots in the extruded
frame of modular conveyors let manufacturers
add, remove, or customize packaging
lines with side guides, sensors, and
vision systems
Modern conveyors do more than move
products from point A to point B. They
form an important link in the packaging-
line chain. Modular chain conveyors
protect productivity, maximizing return
on capital investment for the entire line.
Using chains, curves, curve wheels, lateral
guides, conveyor profiles, and variable
speed drives, a well-designed conveyor
can handle most applications without
costly alterations. Modularity tackles challenges such as product tipping,
product jamming, and the
special handling needs of unusual
or delicate packaging.
Modular chain conveyors relieve
bottlenecks and other product-
flow problems through line
buffering and accumulators. They
adapt to different speeds, infeed/
outfeed demands, production disturbances,
labeler changeovers,
and line stoppages.
Good conveyors also improve
the operator’s experience by making
processes accessible. No conveyor
layout should ever impede
operator movement around the
labeler, checkweigher, case packer,
palletizer, or other manually operated
equipment. And a smart layout
shrinks the footprint, thereby
reducing operator movement and
boosting productivity.
Preengineered components
— from turns and guide rails to
motor and drive systems — combine
to form customized layouts.
A stable chain that can handle tensile
forces up to 1,250 N, at speeds
up to 300 fpm, saves money by using
fewer powered drives. Also, a
tightly designed chain minimizes
gaps between links, making it possible to
convey small components.
Compared to steel, extruded-aluminum
conveyor frame and plastic chains can
adapt to new sizes and labels, while purpose-
built, welded-steel designs are normally
dedicated to a specific task. This distinction
can be crucial in consumer products
where package design is fundamental
to function and brand differentiation.
Spiral buffers made from steel are difficult
to weld, not easily expanded, and typically
do not survive beyond their original
deployment. Conversely, modular conveyors
reconfigure for elevation changes, improved
access, or changing infeed needs.
Standard vertical curve modules, usually
ranging from 5 to 90°, can combine with
static friction or cleated chain for pitched
conveyance without additional transfer
points or secondary equipment. This
means minimal additional investment,
faster implementation, a smaller footprint,
and less risk of damage.
Engineers should look for a range of tools to simplify conveyor design.
The best conveyor suppliers
offer a complete parts catalog,
selection of components
and configurations, macro components
and functions, and 3D
solid models to simplify the design
process. Some companies
even offer software that calculates
driving power and chain
tensile forces, thus ensuring
proper component selection.
A recent PMMI-commissioned
study examined the
challenges in running multiple
products and packaging formats
on a single packaging line.
It found that slow changeover
time ranked highest among
equipment-related factors that
inhibit productivity. And 62%
of companies in the study reported
handling more products
or size variations on their lines
than they did the year before.
Flexibility means easy expansion
and reconfiguration,
including curves and inclines.
Modular conveyors can run
several SKUs on one line by
simply adjusting mechanical
side guides. Quick-adjust and
positive-positioning elements
incorporated into side-guide
systems ensure both speed
and repeatability of changeovers,
including multiple label
changeovers.
Finally, filling operations with
downstream labeling typically
have multiple label changeovers,
even for the same product.
RFID mandates can affect
labeling standards. The labeling
area, characterized by scaled,
small-radius turns, can feature
a buffering system that diverts
material from the main line
while the labeler is changed.
The serpentine design of typical
snaking conveyors takes up
additional floor space, whereas
modular chain conveyors can
form upward-spiralling tiers.
Make Contact
Bosch Rexroth Corp.,
boschrexroth-us.com