The wide range of uses for polyethylene products calls for an equally wide range of polyethylene materials.
The two main varieties of raw polyethylene are high and low-density polyethylene (HDPE and LDPE). High-density polyethylene is characterized by its strength, thickness and durability; it is used in the transportation of high-volumes of liquids or pressurized gasses. It can be corrosion-resistant and resistant to impact.
High-density polyethylene is characterized by rigidity as opposed to LDPE’s flexibility. LDPE is more suitable in applications in which the tubing is attached to equipment that is mobile moved frequently or when used in other applications that require tubes to be easily movable.
There are many methods by which all of the varieties of raw polyethylene materials can be processed into usable tubing products. The most effective, efficient and common method is plastic extrusion. Plastic extrusion is a thermoforming process that takes a raw plastic material and processes it into a useful product.
The plastic extrusion process begins with a collection of raw plastic material called stock. The stock is loaded into a hopper suspended above a conveyance channel. A large turning screw within the channel forces the stock toward a die at the end of the channel. A die is a tool that is used to shape a raw material into a usable product.
In the case of plastic tube extrusion, a die is a metal plate with a specially designed hole and pin through which the stock will pass once heated. Before the stock reaches the die, a combination of the friction caused by the screw and heat from electric heating elements along the channel causes the stock to become molten. It is then forced through the die, and it emerges on the other side as a newly formed plastic tube. It can then be cut to length and prepared for shipment or additional processing.