Path to Safety – Step Seven
January 1, 2010
Material Handling Using Mechanical Assistance
The sixth and seventh steps on
the path to safety lead us to the crucial topic of material handling. Last month we discussed strategies for safe
manual material handling. This month we will focus on the use of mechanical
assistance in material handling as well as other strategies to consider to
reduce injuries. Material handling equipment is used for the movement and
storage of material within a facility or site. It falls into four categories: transport,
positioning, unit load formation and storage.
When transporting material from
one location to another, mechanical devices such as conveyors, cranes and industrial
trucks can be used. Conveyors move materials over a fixed path. Commonly used
conveyors are roller tables which allow the material to be pushed along its
length rather than lifted and carried or a flat belt conveyor which moves the
product along mechanically. Other specialized conveyors exist to meet
manufacturing needs. Cranes are used to move materials over horizontal and
vertical variable paths within a restricted area.
They are able to handle varied
loads with respect to their shape and weight. Commonly used cranes include jib
cranes which can be mounted on delivery vehicles and used to unload heavy
materials at a delivery site. Bridge and gantry cranes are used especially to
move pipe within a distribution center. Industrial trucks are used to move
materials or employees over variable paths, with no restrictions on the area
covered by the movement.
This category includes such
commonly used items as hand trucks, pallet jacks, lift trucks, and order
pickers. It is important to note that even a device as simple as a hand truck
has many variations. Care must be taken to identify the specifications of the
item to be moved and the best hand truck model to perform the task. For
example, if 55 gallon drums are to be transported, choose a hand truck designed
specifically to handle drums. If water
heaters and boilers need to be taken up and down stairs, choose a mechanized
hand truck that can “walk” them up or down the stairs.
Positioning equipment is used to
handle material at a single location so that it is in the correct position for
subsequent handling, machining, transport, or storage. Use of this equipment
will raise the productivity of each worker when the frequency of handling is
high, improve product quality, limit damage to materials, and reduce fatigue
and injuries. Commonly used equipment in this category includes dock levelers
and lift/tilt/turn tables. Dock levelers are used at loading docks to
compensate for height differences between a truck bed and the dock.
Lift/tilt/turn tables are used
when positioning involves the lifting, tilting, or turning of a load. Pallet
load levelers are lift and turn tables used in manual palletizing to reduce the
amount of bending and stooping involved with manually loading or unloading a
pallet. It combines a lifting and turning mechanism with a device that raises
or lowers the table as each layer is completed so that loading always takes
place at the optimal height of 30 inches. It turns the pallet so items located
in the back can be easily reached after the pallet is turned. If such tables
are not economically feasible, the pallet to be loaded can be placed on a
pallet jack that is manually raised or lowered to the desired height. If necessary,
empty pallets can be placed under the pallet to be loaded to further elevate
it.
Unit load formation equipment is
used to restrict materials so that they maintain their integrity when handled
as a single load during transport or storage. This category includes pallets,
skids, totes, bags, boxes, strapping, shrink wrap, bins/baskets/racks, cartons
and palletizers. Palletizers are automatic wrapping machines where the pallet
sits on a turn table and the shrink wrap is applied by the machine. If shrink
wrap has to be manually applied, use the lightest roll possible and apply using
a handle to prevent cuts to the fingers. Raise the pallet up on empty pallets
to avoid the bending and twisting that is required to apply shrink wrap to a
pallet sitting on the floor.
Storage equipment to hold product
is found in all of our workplaces in the form of racking, shelves, and bins. Racking
presents several ergonomic challenges that are worth mentioning. It is common
to use multitier racking with material placed on the floor underneath the
lowest tier. The material may or may not
be on a pallet. Placement of material in such a position requires employees to
assume the high risk posture of bending at the waist, leaning forward and
reaching under the rack to access and lift product.
Strategies to minimize the risk
of injuries include:
(1) make the
bin slot taller to allow more upright access to the material;
(2) use a
load leveler palletizer with turn table so the load is at an ideal height of 31
inches and product is within an easy
24-inch reach;
(3) elevate
the load on empty pallets if the top of the load is not higher than mid-chest
height;
(4) have a
regular rotation schedule so the pallets are turned using a pallet jack or
forklift to ensure materials remain within easy reach;
(5) instead
of using the floor, install the lowest tier of racking 12-15 inches off the
floor;
(6) provide
a minimum width of 16 inches between pallets so employees can move around the pallet
to more easily access the material on it.
Material handling is a fact of
life in the workplace. Developing and implementing a compliant material
handling program will lead your company on the path to an effective safety
program and positively impact your productivity, the health and well-being of
your employees, and a better bottom line.
This
article was written in conjunction with participants in the OSHA and ASA
Alliance. It does not necessarily reflect the official views of OSHA or the
U.S. Department of Labor.
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