We are all familiar with the one-time shipment packaging products available. Our computer monitors, laptops, and Televisions typically come in custom Styrofoam packaging. Basic packages might come with bubble wrap or messy shipping peanuts. If you are packaging highly sensitive units or units that will be shipped many times – reusable packaging products should be considered.
In Reusable Packaging products, Styrofoam, bubble wrap, and peanuts are typically replaced with more durable foams. The two most used foam types in reusable packaging are Polyurethane and Polyethylene foams.
Polyurethane (PU and also called Polyester) – is a spongy foam like the consistency of foam used in pillows or mattress covers. It is an open cell material which means it will absorb liquids. This foam is used for packaging extremely light weight units and is used when the foam is in contact with delicate areas of units that are susceptible to scratching – such as the face of LCD or plasma TV’s and computer monitors.
Polyethylene (PE) – is more rigid than Polyurethane. It is closer to the properties of Styrofoam but is much more pliable and flexible. Styrofoam can easily be broken if bent but Polyethylene foam will not split or break when bent. Polyethylene foam has closed cells so it will not absorb liquids. This foam can be used for packaging most any unit and is many packaging designers prefer using it because it does not absorb liquid.
Polyurethane is a dark gray color. Polyethylene is black. (both come in many colors – white, yellow, blue, etc.)
There are different densities of both. The most common is two- pound per cubic foot density. A cubic foot is 12″ x 12″ x 12″ so the two-pound denotes the weight of a solid one foot cube block.
Four, six, and nine pound per cubic foot densities are also available. The nine-pound Polyethylene foam is the density of a soft wood. This would be used in applications where a unit weighs several hundred pounds.
The cost of the Polyurethane vs. Polyethylene are very similar but the cost increases with higher density foams.
Foams Used for Typical Units
Polyurethane – Hard Drives, cameras, lenses, lights, music recording units, microphones, and sensitive electronic components.
Polyethylene – Large Plotters, rugged units like metal fixtures, microphone stands, heavy industrial machine parts, large speakers or amplifiers, heavy cables or cords.
In highly sensitive environments where static electricity is an issue, anti-static foams are available. Both the standard Polyurethane and Polyethylene foams can come with anti-static properties which help dissipate the electric charge inside a package.
The anti-static foams come in the same densities as standard Polyurethanes and Polyethylene foams.
Anti-static foam comes in a pink color to make them stand out from standard foams.
Anti-static foam is typically twice the cost of standard foam.
Cross Link Polyethylenes are used in applications where Foreign Object Debris (FOD) is a concern. Standard Polyethylene foams have air pockets throughout but the Cross Link has a flat surface area. This helps reduce the foam particles that are created by the friction between the foam and unit as it is removed and placed into the foam.
Cross Link Color
Cross Link can be found in a light gray color as well as black or charcoal.
Cross Link Cost
Cross Link can be three to four times greater than standard foam costs.
Alternative to Cross Link
Standard Polyethylene foam can be heat treated to reduce particulates. The foam surface is treated with a high powered heat gun. The heat melts the open air pockets and creates a shiny smooth surface that helps reduce particulation. This will add some labor to the cost of the foam interior but is a less expensive option than using cross link. There are also some small cell options of PE foams available, like SoftFoam that mimics some of the properties of Crosslink without the high cost.
High Density Polyethylene Sheets
High Density Polyethylene (HDPE) sheets can be used in foam cushions where a heavy item has a small surface area in contact with the foam. The nose of a missile, sharp end of a drill tool, or sharp metal edges of industrial units are all examples of small surface areas.
HDPE can also be used as support in a removable tray. The HDPE will give the tray some rigidity while being removed from case.
Typically color is black, but can be white or gray. ABS can also be used.
HDPE comes in several different thicknesses most common is 1/8″, 1/4″, and 1/2″ thick sheets.
A good packaging specialist will ask several questions about the units being packaged and the environments where they will travel to in order to pick the correct foam for your application. Price, lead time, and ease of assembly are all areas that a designer will consider while designing the right packaging for a project.