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About:
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Rotational Moulding: The Process & Advantages
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<p>
<a href="http://www.rotomoldingchina.com/rotomolding-machine/"
target="_self">Rotational moulding</a>, also known as rotomoulding, is a plastics
moulding technology which is ideal for making hollow articles. It is a casting
technic but unlike most other plastics processes there is no pressure involved.
Moulds for the process are relatively inexpensive as they do not have to withstand
pressure and therefore relatively short production runs can be made very
economically.
</p>
<p>
Rotomoulding is used to make a very diverse range of products. The process
offers the product designer exceptional freedom as just about any shape can be
produced. There is almost no limit to the size of mouldings and there are
literally thousands of applications.
</p>
<p>
The Process
</p>
<p>
The concept of rotational moulding is very simple. A plastic material,
normally in powder form is placed into a hollow mould, usually made from cast
aluminium or fabricated from sheet steel. The mould is closed and rotated slowly
on two axis. The mould is then heated in an oven whilst rotating and the polymer
gradually melts and ‘lays-up’ on the inside of the mould. Once the polymer
powder has fully melted the mould is moved to a cooling station and cooled usually
with air and sometimes a fine mist of water. As the mould cools the part
solidifies. When the material has finally cooled sufficiently to release away from
the mould surface the process is stopped and the product is taken out of the mould
(de-moulded).
</p>
<p>
Whilst the concept of rotational moulding is extremely simple anyone who has
ever been involved in the process will tell you that it is in fact extremely
complicated. It is a casting process and there is normally no pressure involved
which means that the material cannot be controlled in the same way as high
pressure processes such as injection moulding. There are many variables that can
affect production and the end product such as ambient temperature and humidity,
type of mould, material specification and powder quality.
</p>
<p>
Materials
</p>
<p>
Today the industry is heavily dependent on Polyethylene (PE) and 97% of
rotomoulded products are made from this material. Polyethylene is a versatile,
easily mouldable and readily available polymer which has come to dominate the
process. Rotomoulding is a casting technique in which powder is nearly always used
rather than granules, meaning the material must be ground. Polyethylene is
relatively easy to grind at ambient temperatures.
</p>
<p>
The development of other polymers has been hindered by the fact that the
process is relatively long and therefore aggressive on polymers, however there is
some usage of PVC (usually in liquid plastisol form), Polypropylene and Polyamide
(PA6, PA11 & PA12). Many of these non-Polyethylene materials are difficult to
grind and most need to be made into powder using cryogenic grinding – that is
freeze grinding, which is a more costly process. There is a welcome increase in
R&D to expand the range of materials available to the industry.
</p>
<h2>
Uses And Advantages Of High-Quality Plastic Pulverizer Machine
</h2>
<p>
When deliberating on <a href="http://www.rotomoldingchina.com/rotomolding-
auxiliary-machine/pulverizer-machine/" target="_self">high-quality pulverizer
machines</a>, take a look at the plastic pulverizer machine.
</p>
<p>
The plastic pulverizer is a piece of magnificent equipment used in crushing
plastic into small and tiny sizes.
</p>
<p>
Former plastic pulverizers are highly difficult and complex and the results it
produced are inaccurate sometimes.
</p>
<p>
To solve this problem customized powder pulverizer machines are
introduced, and they generate colorful masterbatch.
</p>
<p>
All thanks to the manufacturer of the high-quality pulverizer. With this
machine, you have the chance to achieve standard quality and colorful powder used
in the manufacturing and compounding of masterbatch.
</p>
<p>
Also, the plastic pulverizer machines give the perfect and equal size of
particles which ensures an adequate blending and mixing of additives.
</p>
<p>
Furthermore, plastic compounds such as Polycarbonate (PC), Polyamide (PA), and
Polyethylene terephthalate (PET) are processed in an ambient heat through this
processor.
</p>
<p>
Once this is ongoing, the downstream fan will transfer the end product into a
cyclone from the disc mill.
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