Plastic bins differ in their design and function from plastic bottles and plastic food containers in that they are generally not used for food storage or distribution, and they are generally not disposed of unless damaged.
Plastic bins are very similar to plastic tubs and storage containers, both of which are also used for long term storage or distribution of large objects. Plastic bins, tubs and storage containers are typically made of sturdier materials than other plastic products; this is because they must be able to protect their contents and resist damage caused by contact with extreme temperatures or with other objects while in transit or storage.
Polypropylene and sometimes polycarbonate and PVC are used for heavy-duty plastic storage materials because of their strength and durability. Because the average shelf life of a medium to large-sized plastic storage container is intended to last as long as possible, they are not generally designed or marketed as disposable products. To extend the longevity and improve the marketability of their plastic bins, some companies offer post-purchase bin cleaning services.
Plastic bins are often produced by a process called blow molding. Blow molding machines begin with a collection of raw plastic resin, which is called stock. The stock is loaded into a hopper, and it then travels into a conveyance channel. A long screw in the conveyance channel moves the stock toward the mold as it turns. As the stock approaches the mold, it is heated by heating elements along the conveyance channel. The combination of that heat and the pressure and friction caused by the turning screw helps to liquefy the plastic.
At this point, the liquefied stock is forced into the mold cavity, which in the case of plastic bins is shaped like a large, empty bin. Compressed air is then blown into the cavity, which forces the plastic up against the walls of the mold and creates a hollow recess in its middle. The plastic is allowed to cool and harden and is then extracted from the mold, cleansed of imperfections (if they are present) and either shipped to the customer or sent for additional processing.