Extruded Plastics
Plastic profiles, plastic
channels, plastic
rods, plastic
tubing, plastic trim and plastic
sheets are all extruded plastics which play a vital role in virtually every
industry, from consumer to automotive to medical. Plastic
channels and profiles can have almost limitless length and are manufactured
into window profiles, building siding and trim, gutters and channels, sealing
sections, hoses, curtain rods, tubes, pipes, drinking straws and many other
common products. Extruded plastic
sheets are used in packaging and are often thermoformed into consumer products
and packaging. The extrusion process is highly customizable and is capable
of high volume production as well as short runs, making plastic extrusion one
of the most diverse and economical methods of plastic fabrication.
HDPE, LDPE, PETG, PVC, butyrate, vinyl, polypropylene and polystyrene are all
plastics which are commonly extruded. The extrusion process begins with raw
plastic pellets or flakes being fed into a hopper placed atop a closed extruding
channel; gravity feeds the raw plastic material down into the extruding channel.
Running through the length of the channel is a screw conveyor which moves the
raw plastic along towards the opposite end, shearing and heating the plastic
through friction. The plastic pellets "plasticize", or melt, as
they move through the conveyor, and on the end of the conveyor channel a die
is secured which forms the molten plastic into a specific profile as it is
pushed, or "extruded" through by the screw conveyor. The newly
formed plastic profile is instantly cooled with cold water, pulled through
by a series of conveyors and cut to appropriate lengths. In this way plastic
profiles, channels and tubing are manufactured quickly and at fairly high volume.
Plastic sheeting is
extruded in a similar way, except the molten plastic is pushed through flat or
semicircular dies then stretched into flat sheets, cooled through a series of
rolling calendars and wound around spools. Sometimes additives and coating resins
are added to the surface of the plastic sheeting during the calendering process.
Extruded plastic
sheets are an essential part of the plastic fabrication industry, since most
thermoforming processes use plastic sheeting of various gauges as a raw material.
Point of purchase displays, blister
packaging, disposable eating utensils and many other products are made through
thermoforming processes such as vacuum
forming and pressure forming.
Plastic
extrusions are responsible for the production of everyday necessities like
PVC pipes, indoor and outdoor window trim, sealing bars, siding, plastic gutters,
plastic sheeting, toys, recreational accessories, and much more. Virtually every
industry uses plastic extrusions, including the automotive, marine, packaging,
plumbing, construction and medical industries. Plastic
rods and thick gauge sheets are machined by automotive, aerospace and construction
industries into parts for close tolerance applications. Since the extrusion process
uses a continuous output of smooth, thoroughly heated and mixed material, extruded
plastics seldom have bubbles or inconsistencies, and they are therefore valued
for their structural integrity and consistent profiles.