The Rotational Moulding Process
Rotational moulding makes it possible to manufacture economically a
limitless range of sophisticated products in a variety of colours,
complex shapes and sizes, some of which are impossible to produce by
any other moulding process.
Rotomoulding is ideal to manufacture either simple or complex hollow
plastic products. Containers and water tanks were the most common
products made using rotational moulding and started out as very
simple designs. Recent advances mean that we now mould a wide
variety of products with uses as varied as consumer products,
machine components, marine buoys, point of sale displays, material
handling equipment, plumbing fittings, gardening products, trailers,
light fittings and outdoor sculpture and furniture. The process is
so versatile that the possibilities never cease to amaze.
The rotomoulding process is very flexible and is particularly useful
for small run manufacture or to make and test prototypes. The
Tooling costs are so much less than other processes.
Polyethylene is now one of the most common manufacturing materials.
It has proven to be tough, durable and also UV stable, giving colour
fast longer life and comes in a variety of colours. We can also
mould in polypropylene.
The diagram below shows the Rotomoulding process. If you would like
to know more please CONTACT US.
A pre-determined amount of powder is placed in the mould. With the
powder loaded, the mould is closed, locked and loaded into the oven.
Heating & Fusion
Once inside the oven, the mould is rotated around two axes, tumbling
the powder – the process is not a centrifugal one. The speed of
rotation is relatively slow, less than 20 rev/min. The ovens are
heated by convection, conduction and, in some cases, radiation. As
the mould becomes hotter the powder begins to melt and stick to the
inner walls of the mould. As the powder melts, it gradually builds
up an even coating over the entire surface.
When the melt has been consolidated to the desired level, the mould
is cooled either by air, water or a combination of both. The polymer
solidifies to the desired shape.
When the polymer has cooled sufficiently to retain its shape and be
easily handled, the mould is opened and the product removed. At this
point powder can once again be placed in the mould and the cycle