Plastics are a near-perfect storage material. Depending on how they are engineered, plastic containers can be relatively light weight, durable, corrosion and weather resistant, non-reactive, non-porous, sterile, reusable, recyclable, inexpensive, stackable, nestable. They can be constructed to fit the contours of the item they store, or they can be designed as multi-purpose storage products for items of any size. They can be used for safe disposal of medical waste or for organizing a coin collection.
They can be described as bins, tubs or simply containers. The limits of plastic storage container design are only as strong as the limits of engineers’ creativity. Their uses are similarly unlimited, though within the context of a given industry their applications become more predictable. Industry tends to require durable containers that perform in demanding roles. High-Density Polyethylene is among the more popular materials for fabricating sturdy containers because of its natural resistance to heat and stress.
Plastic storage containers are manufactured by blow molding, injection molding or a combination of the two. Both kinds of molding are identical until the last phase of processing. They both begin with a collection of raw plastic resin (which is called stock) that is placed in a hopper. The hopper directs the stock into a long conveyance channel.
A large screw in the channel forces the stock toward the mold as it turns. The friction and pressure created by the turning of the screw, combined with heating elements along the conveyance channel, heats the plastic to near-liquefication. At this point, methods of plastic molding diverge. In blow molding, the plastic would enter a mold cavity where it would take the shape of the outer mold.
Compressed air would then be forced into the cavity, forcing the inside of the mold to become hollow. In injection molding, the plastic would simply be injected into the mold, which has been pre-shaped to give the liquid plastic its own shape. In both cases, after the plastic has taken the appropriate shape, it is allowed to cool and harden. The newly molded plastic is then ejected from the machine, cleansed of imperfections (if they are present) and either shipped or sent for additional processing.