There are many applications for which the use of clear tubing might be required. Many banks feature drive-through services, and the transportation of money, checks and receipts between vehicles and indoor bank tellers requires the use of vacuum tubes and a mobile container.
Many industries require a container being shipped to be visible in the shipping tube, therefore the tube must be clear. In healthcare settings, clear medical tubing is required to measure and monitor the flow of liquids in intravenous medication delivery and in the movement of fluids between equipment in laboratory settings.
Marine and automotive products and services industries, municipalities and many other industries make extensive use of plastic tubing for a variety of purposes. Plastic tubing can be made from nylon, high or low-density polyethylene (HDPE and LDPE), PET, polystyrene, polypropylene, ABS, polyurethanes and many other raw plastic materials. Many of these materials can be engineered to be clear.
The most commonly used materials for the creation of clear plastic tubing are acrylic materials and vinyl because of the high level of transparency they can achieve.
There are many methods by which raw plastic materials are formed into usable products. Before they can be formed, though, they must be engineered. PVC, for example, is among the more easily identifiable varieties of plastic material. But PVC does not always appear in its trademark opaque, off-white form. It can be engineered to be semi-transparent, as can many other plastics that more frequently feature opaque surfaces.
Only plastics like acrylics, which are naturally clear, do not require special engineering to become transparent. Once engineering of raw materials is complete, raw plastic materials meant to become plastic tubing are usually fabricated by extrusion. Plastic extrusion is one of the thermoforming (heat forming) processes used to turn raw plastic materials into usable products.
The process begins with a collection of raw plastic, or stock, in a hopper suspended above a conveyance channel. Once dropped into the channel, the stock is compressed and heated by a long turning screw. The stock is heated until it reaches a molten state and is then forced through a die, which is a tool used to shape raw materials.
The stock emerges on the other side of the die in its new tube shape, after which it is allowed to cool and harden. The new tubing is then cut to length and prepared for shipment or additional processing.