Figure 3. Wood pallet.

Figure 4. Plastic pallets.

Skids and Skid Boxes:

Skids and skid boxes are frequently used in manufacturing plants, which are often made of metal, and too heavy to be lifted manually. 

Figure 5. Skid boxes stacked and accessed by a counterbalance lift truck.

Tote pans are used to unitize and protect loose items. Returnable tote pans have become a popular alternative to shipping in cardboard containers. When empty, tote pans should nest or collapse to insure high space utilization. Also, tote dimensions should coordinate with case and pallet dimensions to insure high utilization of material handling vehicles.

Figure 6. Tote pans used for parts storage.

In addition to the use of containers (skid boxes and tote pans) and platforms(pallets and skids) to unitize a load, special equipment has been designed to facilitate the formation of a unit load. These special equipment automatically create the pallet of cartons, and automatically remove cartons from the unit load. Examples for unitizing equipment are stretchwrap and shrinkwrap equipment , strapping equipment, palletizers and depalletizers.

Stretchwrap and shrinkwrap is used to unitize a load. Shrinkwrapping is performed by placing a plastic bag over the load and applying heat and suction to enclose the load. Stretchwrapping is performed by wrapping plastic film tightly around a load, multiple layers can be applied to obtain the same degree of weather protection provided by shrinkwrapping. Some companies use fully automatic stretchwrappers while others use systems which are the upgraded version of manual stretchwrapping machines.

Figure 7. Stretchwrap equipment

Whether it is an upgraded or fully automatic system, the following are the advantages of stretchwrapping:

1. Material Savings: An automated equipment prestretches the film 200-250% before it is ever applied to the load. A typical handwrap operation will stretch the film 20-40%. The increased film yield usually results in approximately a 50% cost reduction in stretchfilm usage.

2. Labor Savings: Since the automated systems will execute the wrapping pattern automatically, the operator is free to perform other tasks.

3. Consistency: Manually applying the film will not optimize the film's containment properties. In the automated systems the wrapper executes the exact same pattern for each load.

4. Safety: Repetitive motion, risk of back injury, brief disorientation in high traffic areas, are only a few of the reasons why warehouse and manufacturing operations have switched to an automated wrapping process. Plastic wrap is less likely to cut a hand than a steel strap, is much safer for the personnel and for the end users.

5. Reduction in Product Damage: This really goes back to the consistency issue. In a hand wrapping operation no two loads are wrapped alike. Especially in high volume operations, worker fatigue will result in varying wrapping patterns, and varying wrapping tension. The substandard results provide the likelihood of shipping damage.

6. Product Recovery Costs: If the wrapping is inconsistent, not only has the product been damaged, but now you have the added expense of product clean-up and return transportation costs.

8. Solid Waste Reduction:This has become an important issue as disposal costs continue to rise. Logically, using half as much film to do the same wrapping job will reduce the end users' film disposal costs by 50% as well.

9. Ability to Wrap and Weigh in One Step: If a scale is added to an automated system, productivity can be improved by having a two step wrap and weigh process. Performing this operation in one step saves time, material handling, and floor space.

Palletizers and depalletizers are used for case goods handling as well as can and bottle handling. Palletizers receive products and place them on a pallet according to prespecified patterns. Depalletizers receive the pallet loads and remove the product from the pallet automatically. A variety of sizes and styles area available for both palletizers and depalletizers.

Automatic palletizers are high speed systems to efficiently palletize corrugated cases and trays or plastic crates.Automatic palletizer's mechanical operation provides for a very reliable operation at speeds of up to several hundred layers per hour. Some automatic palletizers are equipped with automatic pallet feeders and slip sheet inserters, with the complete system enclosed in an interlocked safety guarding package. Some system can even be configured to handle the output of different production lines at the same time, reducing floor space requirements and cost.

Robotic Palletizing Systems are also available.

Figure 8. Palletizer

Figure 9. Automatic heavy duty, low entry palletizer capable of palletizing cases at speeds up to 15 cases per minute.

Figure 10. Automatic heavy duty, high entry palletizer capable of palletizing cases at speeds up to 60 cases per minute.

Figure 11. Automatic heavy duty, high entry palletizer capable of palletizing two lines at a combined speed up of 60 cases per minute.

Figure 12. Automatic palletizer with high speeds of up to 200 layers per hour.

Automatic palletizers can be grouped as high entry and low entry systems. The advantage of high entry palletizers is that it utilizes the space more efficiently and requires less floor space.