Clamshells are resealable one-piece containers made up of two halves, held together by a hinge. Named after the clamshells found in nature, who also open and close on a hinge, they are typically composed of a rigid plastic like clear PVC or polystyrene. They can, however, also be made of other materials, like cardboard. Clamshells are highly useful, offering products increased visibility and protection from theft, tampering and environmental conditions like rain. They are also very lightweight, carrying an impressive strength to weight ratio. These factors, along with the fact that they are inexpensive to produce, make clamshells popular for packaging, shipment and product display applications in a variety of industries, such as: clothing, cosmetics, electronics, entertainment, food and beverage, healthcare, household appliance, office supply and retail.
Types of plastic used to create clamshells include polystyrene, polyvinyl chloride (PVC), polyester and various other thermoplastics and polymers. Every plastic type offers different qualities. Polystyrene, for example, is hard, clear and inexpensive to produce. It is available a variety of different forms, including solid sheet/molded plastic and foam. In addition to being clear, it can also be colored. It, however, is known to degrade very slowly and its use is regarded dubiously by environmental scientists. PVC, on the other hand, is known as an excellent insulator and resistor of the chemicals in substances like salts, acids, fats, bases, fuels, paint thinners and alcohols. It may be rigid or elastic. PVC degrades much better than polystyrene, but it still should be recycled rather than thrown away. Finally, polyester is unique as well. It is available in different types, with varying hardnesses and thermal and chemical stabilities. Also, polyester clamshells have refreshingly low toxicity levels and are recyclable.
Clamshells can be made using a variety of plastic forming processes, but the most common methods implemented on their behalf are thermoforming, pressure forming and vacuum forming. Thermoforming is a process by which plastic material is heated, stretched and cooled into parts. Pressure forming and vacuum forming are both sub-processes of thermoforming and, therefore, they all begin the same way: First, plastic sheets are fed into heaters powered either by electricity, infrared radiation or natural gas, where they are warmed until they elastic and malleable. Once this step is complete, they are transferred to a forming station, which is where the deviations take place. If, at this point, the plastic is being pressure formed, pressurized air pushes it into a pressure-controlled mold. If, instead, it is being vacuum formed, the plastic will be enclosed in a mating mold and pressure box, where a vacuum will suction all of the air out and pull the plastic into the mold. Both methods are viable, but if a manufacturer is attempting to form a clamshell with greater precision or with more intricacies, pressure forming is the recommended choice, because it yields stronger adherence. Whatever a manufacturer’s choice, once the plastic has cooled, it is ejected from the mold using rigid reverse airflow. At this point in the process, the clamshell exists either as two separate components or a single sheet. If the former is the case, manufacturers proceed by fusing the edges together to create a hinge, using either stamping, welding or heat treatments. If the latter, manufacturers simply fold the sheet to create a hinge, then heat seal it.
These methods create a number of different clamshell types, such as clamshell trays, egg crate clamshells and tri-fold clamshells. Clamshell trays are used to package and display products simultaneously, like, for example, blueberries and other fruit, small tools like screws and pins and any number of other items. Egg crate clamshells, on the other hand, hold and divide products. They are named, of course, after egg cartons, though they also hold other rounded items, like golf balls. Finally, tri-fold clamshells are designed with a flat bottom so they can stand on display. These can be used to hold all sorts of products, like remote controls and other electronic goods, locks, handheld thermometers, sporting goods and more. In addition to these standard designs, clamshells are also available in a variety of custom configurations, and, of course, all clamshells are purchasable in different shapes and sizes. To find out more, reach out to an experienced clamshell and packaging manufacturer today.
Clamshells – Valk Industries, Inc.
Clamshells – Valk Industries, Inc.