Plastic Extrusions in Industry
This is the process of converting raw material
plastic often called resin into various forms of finished products. The
plastic extrusion process is usually done in high volume and is a
continuous process which depending on the targeted end product ,can
produce products such as plastic pipes, plastic rails, polythene sheets,
plastic insulation material and even plastic containers. This process
takes place without changing the inherent properties of the plastic
material. The plastic extrusion process has become very important in
today’s manufacturing as well as environmental management because it has
enabled the substitution of expensive metallic products with plastics
such as tanks, and also enabled the recycling of plastics thereby
reducing plastic accumulation in the environment.
Process Related to Plastic Extrusion
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Sourcing of raw material. Raw material for the plastic extrusion process is supplied in the form of resins called pellets which are made up of polycarbonate material. These pellets could be derived from unused plastic material or from recycled plastic. In the process of manufacture of resin pellets, additives may be added to improve their color and even their structural qualities.
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The extrusion process. It involves feeding the pellets or resins by gravity to a hoper and into the extruder. This is where additives are added. Due to the conical shape of the hoper the material is directed to the other end by gravity where it meets the rotating screw. This directs the beads forward into a heated barrel. The barrel has three heating stages to allow gradual heating of the beads to up to 200 degrees to a set temperature depending on the material being manufactured. Gradual heating also avoids altering the structure of the polymer being used in production. The plastic in molten state passes through a screen removing impurities, to a breaker plate which converts the rotating motion of particles to longitudinal motion. From this stage the particles enter what is called a die and this is where the shape or the design of the final product is obtained from. Any shape can be obtained and it is important to maintain a continuous profile. The final stage now is cooling which involves pulling the unfinished product through a cold water bath.
Tolerances in plastic extrusion
This is the range given or that should be observed during the plastic extrusion
process. This includes the length, width and even the thickness of the
final product required. There is great variability in the tolerances
of the extrusion processes especially due materials used, the cooling
rate and extrusion process used. Faster cooling materials have
stricter tolerances. The challenge of tolerances can be overcome
through more sophisticated calibration and minimizing the pockets of
the final product (slower cooling in pockets).The effectiveness of the
cooling process directly affects the tolerance.
Forms of plastic extrusions
The plastic extrusion process comes in various forms
such as the dies extrusion whereby the final product take the shape of
a mould or die; Sizing products whereby the final product takes the
shape of the bands situated after the die; sheet extrusion where by
cooling is done by passing the product through cooling wheels to
achieve sheets of plastic and tubes extrusion whereby when resin is at
the die point, it is forced through tubes to give tube forms on
cooling. Polythene bags are also made through this procedure. For More
Information Visit - http://www.oceanextrusions.com/profile.html
Plastic extrusion processes are a great innovation in today’s economy
as the use of plastics is increasing day by day. This is more so
because plastics are replacing even metal and wood in industry. This article has been written & posted by Mr. Mrunal Ramanuj.
