Clamshells Photo Courtesy of Valk Industries, Inc.

Clamshells always do their job well, in some cases too well. There have been times when I have bought a new CD player or camera encapsulated within the protective shell of a thermoplastic clamshell wrapping and had difficulty retrieving the product without the aid of a knife or scissors. However, the irritation has always been balanced by the efficiency and safety ensured by this version of vacuum formed plastic. Also, the difficulty in opening a clamshell works as theft protection when items are in a commercial setting while the clear plastic allows buyers to view the product clearly. Both of these details make clamshells a very attractive product packaging option for store owners.

Often the vacuum forming process that creates clamshells begins with sheets of plastic, usually polyvinyl chloride, which is also known as PVC. This is a high strength to weight ratio plastic that is light weight and clear, as well as being fairly inexpensive to manufacture. That is why so many industries, such as cosmetic, medical, entertainment, food and beverage, packaging, clothing, household appliances and electronics all utilize the clamshell design.

The first step in manufacturing a clamshell, regardless of the size and shape, is almost always to insert the chosen sheet of PVC into a heater of some sort, either infrared, electric or natural gas. When the plastic has become soft and pliable, but before it has melted into a molten state, it is removed from the heat. A basic vacuum forming process will enclose the sheet within a mating mold and pressure box, then applying a vacuum to suck all the air out so that the plastic takes the exact shape of the mold. Other variations exist, although most allow the plastic to fully cool on the mold before the plastic is then removed and the hinge is created. The final step is to place the product inside and seal all the edges with a heat treatment.