Ergonomics in the distribution center: picking from pallet hazards and solutions
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Note: this article has specific examples from the grocery distribution industry, but the principles of ergonomics apply to nearly every kind of business that stores and handles materials in a warehouse situation. |
Steps for making workers safer and improving productivity in picking operations
Most goods in the warehouse are stored for a period of time. Racking is used to expand the amount of storage that is possible. Metal racks are used for storage and the area created within the racking is called a pick bin or slot. Slots range in size, depending on the products stored.
Low storage locations cause bending and reaching
Potential hazards:
Palletized product is stored in pick bins.
Typically pallets are placed on the floor, which requires employees
to bend at the waist to access palletized loads that come to the
warehouse stacked only a few feet high, or may be unloaded to the
point where they are only a few feet high. Even when these pallets
are
stored in taller slots, employees must bend at the waist to
access product. This is a significant problem since the heaviest
product is usually in the shortest stacks.
Low racking can force employees to bend at the waist to access loads. Loads in bottom bins will require forward torso bending to reach under the rack, even when the top levels of the stack are at waist height or higher.
Potential Solutions:
Use a pallet positioner: Whenever possible, elevate the pallets within a slot bin. The best technique is to place a palletizer into a tall bin. A palletizer will lower in height under the weight of a full pallet, then will raise the load as items are removed. The use of a turntable (also called a Pallet Positioner) allows employees to reposition the load. This keeps the load close to the body.
Stack empty pallets beneath active ones:
If your pallet does not have product stacked
above waist height, stack empty pallets beneath it to elevate the
load. Care must be taken so the top level of the heavy product is
not raised higher than mid-chest height.
Use a set-low beam on your pallet rack bays:
Raise the bottom level of racking so loads are
at heights where torso bending is not necessary. This method allows
you to rack your pallets normally by lift truck, and reduce the need
for employees to bend over to access the loaded product.
Use a vacuum hoist: Provide a device such as a forklift with a built-in vacuum hoist. The strong suction can lift up to 150 lbs. (Check with hoist manufacturers to confirm load capacity).
High Location Storage - picking product above the shoulder level is an ergonomic hazard
Potential Hazard
Reaching is an ergonomic danger. Employees often reach above shoulder height to access products on upper shelves. This causes stress to the shoulders and back. Additionally, lifts above shoulder height often require awkward hand and wrist postures.
Potential Solutions
Store it higher on your racking—out of hand’s reach: Use elevated rack locations as the overstock storage area. Pallets of product should be lowered to more appropriate heights prior to being selected. Selections should be performed with arms close to the body. This way, employees cannot over-reach for a product. They must use a forklift to access it at all, and best lifting practices are more likely to occur.
Use a Pick Stick: Provide employees with "Pick Sticks" or "Bow Peep" hooks to pull small, light-weight product closer to the edge prior to lifting.
Double or Triple Slot Picking
Potential Hazards
Double or triple slotting is used to maximize shelving space so the greatest amount of product can fit in the smallest amount of space may increase ergonomic stressors such as bending and elevated reaches, as pickers cannot easily access tightly stored items. Most pallet rack is double-slotted. Workers may be forced to bend at the torso to reach under low racking to access product. This product may be stacked at desirable heights that would not otherwise, if not for racking interference, require workers to bend at the torso. Workers must reach above shoulder height to access materials placed on three-tier racking or to access tall, palletized loads placed on two-tiered shelving. In general bottom and top racking in three tiered systems creates significant access issues.
Potential Solutions
Utilize full slotting, especially for product
that is heavy or bulky, so employees can have better access without
undue reaching or bending.
Utilize Flow Storage: Slower moving product
that is fairly compact can be warehoused using gravity fed flow
racks. These racks allow highly condensed usage of warehouse space.
However, hazards can be created by this type
of racking since it
must be loaded by hand from the back of the rack. This can require
repeated elevated reaches, repeated bending of the torso, as well as
using box openers to cut open shipping boxes. Also, Selectors must
pull product over the stop lips that keep the product from sliding
out onto the floor. Heavy product in the slot creates additional
pressure when lifting boxes over the stop lips.
More information on Flow Storage.
Reaching into pallets for product picks
Potential Hazards
Product is often removed from the front of pallets first. This leaves the remaining product stacked in the back of pallets, where employees must reach to access and lift product. This creates additional stress on the shoulders and back.
Possible Solutions:
Rotate the pallet on a regular basis: Develop a product rotation process where pallets are regularly turned using a forklift or pallet truck after the majority of product has been removed. This involves pulling the pallet out of the slot, turning it 180 degrees and replacing it into the slot.
Utilize pallet positioners & turntables: Place pallets on turntables so the pallet can be turned and optimal access to the product can be maintained at all times. More pallet positioner information.
Utilize storage methods that allow pallets to be moved: Roller and channel devices (such as pallet flow) allow the pallet load to be pulled out for better access. Addition of a turntable at the end of such a device will allow the pallet to be turned and then replaced into the slot with the load closer to the front.
Widen the storage slots to improve access: Provide wider slots, especially for heavier product, so pickers can walk into the slot and access all sides of a stored pallet. Stockers should be trained to leave at least 16 inches between pallets so there is enough space for Selectors to move around the pallet during selection.
Aisle width
Congested aisles cause product to be hand-carried longer than it should be, or be accessed from incorrect positions
Potential Hazard:
Aisle width may be insufficient for access to faster-moving product. This may create congestion that forces pickers to stop farther from the pick slot and carry product longer distances to the pallet jack. They may be tempted to carry multiple parcels at the same time to save trips.
Possible Solutions:
Widen the aisle: Increase the width of aisles where fast-moving product is located. This will allow more pallet jacks to get closer and will reduce the distance that loads must be carried.
Schedule for access: Stagger the start times for Selectors at the beginning of the day so that fewer Selectors hit the same slots at the same time. Five to ten minute start differentials should provide adequate spacing for sufficient disbursal of Selectors.
This article can be found in its original place at the OSHA website.
