Reusing corrugated cases has long been a trick of the snack food
industry to cut packaging costs. For many manufacturers, cases remain
within the confines of their route-delivery distribution system.
But once those cases are knocked down and returned to manufacturing,
they’re often too flimsy to be erected, packed and sealed
on conventional equipment. “Used” cases typically must
be erected by hand, even for large-volume producers.
Snack maker Herr Foods, Nottingham, PA, believes it’s one
of the first to buck the trend. In February ’96, it finished
installing five case packers from Blueprint Automation (Richmond,
VA) that were custom-made specifically to erect, pack and seal used
cases. The cases are used on five lines that pack a variety of bagged
snack foods including pretzels, popcorn, cheese curls and tortilla
chips. The products are sold in the Northeast and Mid-Atlantic regions
under the Herr’s brand name.
What makes the Blueprint machines different is the degree of control
they expert over the case, according to Steve Moran, plant engineer.
“In the past, we’ve experimented with case erectors
that have had problems controlling the flaps. These machines positively
control every single flap on that box,” he explains. “There’s
no chance of a flap bending in the wrong direction on hanging down
where it shouldn’t.”
Part of the solution is a modified case design. For this application,
Herr’s switched to a special self-locking design that eliminates
the need for adhesives or tapes. That means cases come back free
of any tape or adhesives. Special die cuts in the minor flaps allow
the corners of the major flap on the box top to be folded in automatically.
The bottom flaps were also similarly designed to be self-locking.
Cases are 200#-test, C-flute, and are purchased from several suppliers.
Multiple trips
Moran emphasizes that not every case is reusable. In rough numbers,
Moran says Herr’s ships almost twice the number of cases it
buys. At each of Herr’s 20-odd distribution branches, damaged
or otherwise unusable cases that are returned by route salespeople
are sorted out of the system. A second such sortation occurs at
Herr’s Nottingham headquarters production facility. Cases
that do make it through the recovery and sortation process typically
make at least two or three trips. Indeed, four or five trips isn’t
unusual, according to Moran.
Even so, the payback of these machines is not dependent upon the
recovery of cases or even the number of trips each case makes. Cases
were being reused at about the same rate before the installation
of the equipment. The real savings are in labor. Previously manual
case-packing required one to two people for each of the five lines.
Today, those people are freed up for other tasks. Further, no new
operators were added; the machines require attention from bagger
operators only for replenishment or to clear an occasional jam.
With two and sometimes three shifts, Moran estimates the return
on the investment at two years. A unique twist to this application
is a Universal corner labeler from Park Products (St. Petersburg,
FL) that’s integrated into the case packer. Elmark Packaging
(West Chester, PA), which distributes the labeler, modified it to
fit in the small space allotted to it. This label’s bar code
is then scanned in Herr’s automated warehouse for automatic
sorting and palletizing (see sidebar). “The case packer automatically
erects, fills and closes each case, and sends it out in the warehouse
without anyone every touching the case,” says Moran.
Arms do the work
The case packers are installed on five lines in Herr’s allied
snacks area, which manufacturers all snacks except potato chips.
Each case packer is connected to existing vertical f/f/s equipment.
The machines produce bags that range from 4 to 20 oz, at speeds
from 12 to 45 bags/min. Case counts range from 9 to 16 bags and
finished output averages two to three cases/min. PW had a chance
to the machines in action during a recent visit.
Case erecting starts out as operators load used (or new) case blanks
in the machines’ horizontal stacking magazine. The entire
magazine indexes forward into the machine, permitting a second stack
to be created while the machine uses up the first. A vacuum head
lowers and attaches to the surface of the corrugated. As the head
elevates, the relaxed blank opens up by gravity, but doesn’t
square up. Squaring is handled by a series of pneumatic arms that
push in from either side.
Additional arms push down and in on the major and minor flaps that
form the bottom of the case. A final arm gives a good poke to the
case bottom, causing the flaps to lock one against another. The
vacuum head continues to retain its grip until the case is summoned
by the loading section.
When product is ready to be loaded, the vacuum head holding the
case moves forward and then down, depositing the case into the loading
cassette. The case is top-loaded as it sits on its side so that
horizontally layered bags are simply pushed into the case. When
the case is eventually turned upright, bags are vertically oriented,
which provides protection during transit.
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Finished
cases are elevated to an overhead conveyor that leads to the
warehousing area |
Bag collation
Meanwhile, at the other end of the machine, bags are conveyed from
the vf/f/s machine up an inclined conveyor into the collating area.
The conveyor is equipped with two belts that compress the bag as
it travels, testing for seal integrity. Airtight bags resist the
compression, passing inspection. Sensors detect a lack of resistance
from leaky bags, signaling a reject.
At the top of the inclined conveyor, bags are dropped into a mechanism
that meters the bags into the collation section at appropriate intervals.
Bags are dropped intermittently onto what looks like two parallel
rubber tank treads that support the bags at each end. After each
bag is deposited, the treads advance the distance of one bag width,
until an entire row of bags is formed. At that point, the treads
drop away and the bags drop as a group a short distance onto a staging
platform. A ram pushes in from one side, squaring the bags as a
group. The platform is then withdrawn, whereupon the bags drop further
into a containment bin that mimics the size and configuration of
the case. Once the desired number of layers drop into the bin, its
contents are ready to be transferred into the waiting case. To accomplish
this, the entire back wall of the containment bin is actually a
ram that pushes the bags into the case.
Loaded with product, the case makes a 900 turn, still on its side,
toward another station whose purpose is to close the top of the
case. As the case travels, the left and right minor flaps are closed
by an air cylinder. That keeps the bags from falling out. Once in
the top closing section, a tucker and air cylinder crease the dominant
major f lap-which covers about two-thirds of the top of the case.
The flap is then guided into die-cuts in the minor flaps.
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For case closing,
tuckers can be seen guiding the top major flap on the specially
designed case into die-cuts on the minor flaps. |
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| Here the pneumatically driven arms can be seen squaring
the case and folding in the bottom. |
Once the lid is closed, the case is tipped onto its bottom and
presented to the stepper-driven corner labeler. It consists of a
pneumatic applicating head that applies a small preprinted bar code
label from rollstock. A human-readable product code and description
are repeated on what becomes the side and end panel. A bar code
appears only on the side panel, which is read by the scanner in
the automated warehouse. Route delivery drivers need to see the
human-readable code on the ends of the cases, since cases are stacked
with the end facing out in route delivery trucks. The labels, also
from Elmark, receive a pull date that’s printed at the point
of application by a roller coder.
Each label is applied on top of any previous label that may already
exist. In fact, that’s how Herr’s personnel can tell
the number of trips through the system for a given case. Once the
case is labeled, it is conveyed into an elevator that lifts the
case to an overhead conveyor.
The Blueprint machine incorporates all functions-case erecting,
bag inspection, bag collating, lid closing, labeling and case elevation-onto
one fairly compact machine frame that fits in the available space.
“Most snack food manufacturers have laid out their lines without
thinking about automatic case packing,” says Moran, “and
everyone’s locked into an eight- or nine-foot machine centerline.
It can be hard to fit a big case packer in that space.”
No-tool changeover
The Blueprint machines can be changed over to a new pack pattern
and case size in about 20 min without tools, according to Moran.
Changeover involves selecting a new pack pattern from the Allen-Bradley
(Milwaukee, WI) Panel View 550 operator interface, which is connected
to an A-B SLC 5/03 PLC. (Herr’s has standardized on A-B for
all of its controls) The PLC instructs the collating mechanism how
many bags it should accumulate on each row, and how many rows should
make up a case. Some quick mechanical adjustments are made via hand-wheels
to the case magazine to accommodate different case sizes.
To simplify case changeover, the three case sizes used on this machine
all share a common footprint, which is 20” L x 15” W.
The only difference is case height, which ranges from 83/4”
to 133/4”. Moran points out that a change in bag size or pattern
that doesn’t require a case change can be done in 10 min.
And many times operators won’t make any mechanical adjustments
to change a bag size that’s only 2” or so shorter; the
new product code is simply selected.
Twin-tube packing next
With the five Blueprint case packers behind him, Moran is focusing
his attention next on case-packing small-bag production. Smaller
bags, weighing ½ to 2 oz. Are harder to pack automatically
due to their light weight.
Some bags are currently packed by hand, though Herr’s is experimenting
with a robotic packer on two potato chip lines. However, Herr’s
is investigating a new Blueprint machine that’s designed specifically
for small bags. Moran, who recently saw the machine operating at
another manufacturer’s plant, was impressed with its ability
to pack the lightweight bags as efficiently as the larger bags,
while still offering reusable case compatibility.
Though the Blueprint machines have proven themselves in a real-world
application, Moran cautions that automating with reusable cases
still requires a lot of human involvement, mainly sorting out bad
cases before they are delivered to the packaging floor. Even so,
occasionally a bad one slips through.
“You’ll get one case out of every 50 that doesn’t
work,” says Moran, “but that’s because it may
have been torn and should never have gotten into the machine. It’s
a learning curve that you have to go through.
For more information contact:
Robbie Quinlin
Phone: 804-520-5400
E-Mail: robbie.quinlin@blueprintautomation.com
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