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About the
Rotational Molding Process
Rotational molding is a four-stage process, which
comprises loading, heating, cooling, and unloading the
mold. A mold is charged with polyethylene plastic and
rotated simultaneously about two axis. The rotating mold
is placed in an oven to let the plastic uniformly adhere
to the inside mold surfaces and then cooled to let the
plastic solidify. The polyethylene powder is a free
flowing agent that can get to all parts of the mold as
the mold rotates. The small particles of powder ensure
efficient heat transfer as they come in contact with the
mold to produce a custom rotationally molded product.
Since the molds are relatively inexpensive compared to
injection or blow-molding tooling, this process lends
itself to low volume start up production. It is ideal for low
part quantities or large volume production of small to large
hollow plastic parts.
A few examples of Plastic Rotationally Molded products
are industrial parts, environmental tanks,
playground equipment, bumper guards, specialized seats,
stable equipment, outdoor garden products and anything
with a complex hollow shape. Plastic products are
durable and offer high impact toughness while allowing
flexibility and incredible design versatility.
Materials
Predominantly rotationally molded parts are produced
from polyethylene; LLDPE, LDPE, MDPE, HDPE and XLPE.
Other materials that can be rotationally molded include
acrylic, polypropylene, nylon, PVC, PUR and TPU.
Development work is currently being undertaken to
produce grades of ABS that can be rotationally molded,
at this time, none are commercially available.
The
Advantages of Rotational Molding
Unlike other plastic molding processes, rotational
molding results in seamless parts with uniform wall
thickness. Due to the flow of the material in the mold,
material adheres in the corners resulting in incredibly
durable products that can absorb shocks and stresses
where they occur most.
Since rotational molding is a stress-free production
process, the finished part is stronger. Molds are not required to withstand the high pressures of
injection molding, therefore tooling is simpler and less
expensive.
We offer a variety of services to enhance your finished
product. Molded in color, mold in graphics, metal
inserts and molded in threads.
Advantages of the rotational molding process include:
• Short lead-time
• Economical Tooling
• Large Dimension Parts
• Excellent load-bearing properties
• Stress-free Walls & Corners
• Ability to produce multi-wall moldings, which can be
left hollow or foam-filled
• Low Volume Runs & Color Changes
• Resins can be tailored to suit the application – e.g.,
to satisfy FDA requirements
• Minor undercuts are possible – without the need for
draft angles
Rotational
Molding Applications
Rotationally molded products can now be found in many
applications. Following is a list of a few of the
applications that rotational molding has replaced
traditional metal or plastic processes:
Agriculture: Livestock feeders, shelter, tanks,
drainage systems
Health & Science: Specialty tanks and containers
for fuel, water, and chemical processing, instrument
housings, medical equipment
Point of Sale (POS): kiosks, vending machines,
signage, display panels
Transportation: Highway barriers and road
markers, fuel tanks, seating, marine, headrests, body
panels, manifolds, ducts, RV components
Consumer Products: Boats and kayaks,
toys/balls, playground equipment, childcare seats, light
globes, tool carts, plant pots, portable toilets, trash
receptacles, furniture, lawn and garden
Industrial/Commercial: Shipping / storage pallets
and containers, material handling, spill containment,
housings, cases, ducts, industrial cleaning equipment.
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