Palletization is an important component of materials handling and logistics strategy. (See “Why Palletize?) The primary work of palletizing is the placement of boxes or other items onto the pallet.
The introduction of palletization resulted in substantial gains in material handling efficiency. During World War 2, for example, the palletization of materials in railcars led to one forklift operator being able to unload a car in just a few hours, versus taking two men a day or longer. Gains were realized not only in reducing physical product handling but also regarding facilitating better storage solutions, reducing product damage, as well as in reducing the loading and unloading time required for transport equipment.
There are three basic approaches to palletization. These are manual palletization, semi-automated palletization, and automated palletization. Semi-automated and automated palletization are explored in separate segments. This installment looks at manual palletizing.
As the name suggests, manual palletization involves the placement of items on the pallet by the use of manual force. For example, a worker may lift boxes coming off of an assembly line conveyor and stack them onto a pallet, or if the employee is selecting an order for a customer using a pallet placed on a pallet jack, he or she may remove boxes as required from several pallets to put on the pallet being built for the order. Typically the pallet may be positioned on the floor, or on the forks of a lift truck or a pallet jack. In the accompanying image, a worker is standing on the bed of a truck to stack reusable plastic containers (www.europoolsystem.com) being harvested from a field.
Manual palletization has several benefits versus semi-automated and automated palletization. Such benefits include avoidance of investment in automation, as well as greater flexibility, and in some circumstances, higher speed. While automated palletizers have worked well with uniformly sized cartons, the presentation of a variety of box sizes requires the use of robotic palletizers, which up until recent times have been slower than manual palletization. Robotic palletizers, however, have evolved to the point where they provide extremely good performance in building mixed SKU unit loads.
Avoiding Injuries During Manual Palletization
Manual palletization can be a very demanding and repetitivephysical task. Common injuries involve back and shoulder strain, as well as wrist and forearm injuries. Foot injuries are also common when working around pallets. It is all too common to catch a foot in a pallet opening. Steps to minimize the risk of injury in manual palletization (excluding investment in automation) may include:
- Training on proper lifting technique, such as keeping the load close to the torso, bending knees and not twisting
- Maintaining the lift in the “gold zone” between knees and shoulders by utilizing elevated or rotating platforms when appropriate to limit bending or specifying pallet height to an ergonomically appropriate level.
- The use of conveyors, which present cases to the worker at an optimal height
- Paying attention to foot positioning to avoid excessive reaching
- Redesign of cartons or other materials being palletized to make them better ergonomically, for example, the reduction of case weight and the introduction of hand holds
- Through attention of carton design, stabilize dynamic loads, such as melons, for example, that otherwise might roll to one end of the box if slightly tipped, increasing risk of wrist injury
- Use of a “pick stick” to pull product close to the body before attempting a lift
- The use of a back belt, a practice once considered a best practice, is now very controversial
- In some cases, the use of manual palletizing frames can help promote the building of loads that do not “mushroom” outward beyond the pallet footprint.