ed to replenish the picking area, the appropriate pallets
are retrieved by cranes from the high bay and sent to
depalletizers, where the cases are removed layer by
layer. The cases then pass through a singulator that
places them in-line on conveyors. The conveyors, supplied by Witron’s FAS subsidiary, whisk the cases to an
area where they are gently deposited onto plastic trays
for short-term storage.
The trays, now holding cases, are conveyed to a 56-
aisle tray warehouse, an automated storage and retrieval
system (AS/RS) with 265,000 tray storage locations
served by 56 cranes. Built on
the roof of the existing facility
in Suhr to save space, the tray
warehouse actually acts more
like a buffer than a storage system, as product is held there for
two to three days at most.
When a product on a tray is
needed to fill a store order, the
storage crane in its aisle is summoned to retrieve it. The tray is
then conveyed to one of 28
sequencing buffers. These
buffers are smaller automated
storage and retrieval systems,
where product is held only as
orders are being built. Each of
the sequencing buffers serves a
COM machine where the
orders are assembled.
Algorithms within the system’s software determine how
each pallet in the order will be
built. The idea is to assemble
the pallets with an eye toward
expediting store putaway. Each
pallet is built to one of nine
product family groups, based on shelf destination in
the store. Most of the stores have limited space and narrow aisles, so the ability to quickly restock the shelves is
crucial.
The trays are sequenced out of the buffers in an order
designed to facilitate the building of stable pallets, with
heavier, bulkier items on the bottom and lighter products on top. The bottoms of the trays are dotted with
small holes about the size of a U.S. nickel. As the trays
enter the COMs, metal cylinders poke up through the
holes to raise the product off the tray. An arm then gently sweeps the carton onto a singulator that arranges the
stacking of each layer.
One of the advantages of the system is that it allows
Migros to build taller loads than it could previously, with
loads averaging about 61 cartons per pallet and reaching
up to 1. 8 meters (about 6 feet) high. These taller loads
enable Migros to make better use of truck space.
SWIFT AND ACCURATE
Since moving to the new sys-
tem, Migros has realized a num-
ber of benefits. For one thing,
the new solution allows for
greater speed and flexibility in
its operations. The numerous
built-in buffers enable it to
schedule work when it is most
convenient. The system is also
designed to accommodate sea-
sonal changes in the product
lineup, making it a simple mat-
ter to adjust volumes and introduce new products. On
heavier days, the system is capable of performing as
many as 20,000 picks per hour.
On top of that, the new system has cut down on pick-
ing errors, thereby improving store service. “Picking
accuracy is much higher than it was with our manual
systems,” reports Schweizer. “We are nearly at 100 per-
cent, compared to 99. 5 percent at best before.”
Labor requirements have also been reduced in the
two-shift operation. Before, about 120 employees were
needed per shift. Today, the number has been cut to 28,
making the facility much more economical to operate.
All these benefits notwithstanding, the biggest plus in
Schweizer’s eyes is the order fulfillment flexibility offered
by the system. “It is now very easy to handle different-sized orders,” he says. “We are very happy with the
results, and our stores are also happy.” ;
