equipment
units (SKUs) in the zone fast or slow
movers? Are they picked individually
or in case or pallet quantities? Where
are they stored—on shelving? on
flow racks? in carousels?—and how
far apart are the pick locations?
Because pick to light’s advantage
over competing systems is speed, it
stands to reason that it’s best suited
to fast-moving items. But how fast is
fast moving? Reese of FKI Logistex
considers an item to be fast enough
for pick to light if it moves at a rate
of 300 to 1,100 lines per hour.
Remstar’s Romaine takes a somewhat different approach to deter-
mining if an item qualifies as a fast mover.
“I have a very scientific test,” he says. “I
walk up to a rack, and I run my finger
over the second or third line of items. If
there’s dust a quarter of an inch thick,
then it’s not a high-activity item.”
Just how many SKUs will fall into the
“fast movers” category? Although the
answer varies from one operation to the
next, usually the 80-20 rule applies, says
Dave Broadfoot, managing partner of
pick-to-light manufacturer Lightning
Pick. That is, about 80 percent of all
orders will “hit” 20 percent of the SKUs.
The zones containing these SKUs will
benefit most from pick to light.
What makes pick to light a good choice
for fast movers is its ability to provide
picking instructions for several items
simultaneously. With voice and RF systems, order pickers must wait for the
computer to tell them what their next
pick is, according to Gillespie. With pick-to-light systems, the wait time is eliminated. All of the displays for items needed for
an order can be illuminated at once, so the
picker can tell at a glance where the next
pick location is.
Prime picks
Another key factor in determining
whether a zone is a good fit with pick to
light is the picking method used.
Generally speaking, pick to light is best
suited to split- or broken-case picking
applications, in which items like single
bottles of wine or power cords are picked
as “eaches.”
Still, there are plenty of companies that
have used pick to light successfully for
full-case picking operations. Lightning
Pick has one customer, for instance, that
decided that voice wasn’t providing the
speed it was looking for in its full-case
picking operation. The company is now in
the process of switching to pick to light.
The type of storage system used in a
zone will also enter into the decision.
Most experts agree that pick to light
works best for items stored in carton flow
racks, with replenishment taking place at
the back end and picking occurring at the
front end. Pick to light can also be used
with static shelving, although that will
keep the operation from taking full
