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We are a full-service manufacturer. We take pride in our state-of-the-art equipment
and our long-term employees. We are noted for our custom ability, but have our own standard product line
of Carts, Containers, Tanks and Trays. Why buy anything but Quality?
MOD rotomolding — custom design & manufacturing specialists in the conversion of metal, fiberglass, wood & other parts or products into complete, integrated, rotationally molded plastic designs. Award-winning MOD engineers help you cut the parts, count, reduce weight, boost strength & add stunning visual appeal.
Trust GemStar’s more than 40 years experience for the finest in rotationally molded plastics. Work with our expert plastic fabrication team to develop the perfect roto mold design for your needs. Our roto molding process produces rugged stress-free custom rotational molded parts.
Industry leader in Nylon and crosslink polyethylene hydraulic tanks, fuel tanks, coolant/washer bottles, shrouds and air ducting. Offer solutions for new and emerging fuel permeability requirements and Metal to plastic cost saving conversions. Promote customer focused innovative design solutions.
Interpak specializes in high-quality rotationally molded plastics, custom rotomolding and rotomolded containers. Interpak rotomolders offers quality, cost-effective products for all your rotomolding needs. For more information about our products and services please call or visit our website.
We have a first. Production of the first permanently installed rotationally molded plastic marine-industry fuel tank happened here. We make other custom products via rotomolding. Construction, industrial, lawn and garden, material handling and recreational industries order from us. In business since 1979.
Rotational molding is a process by which plastic goods
are formed and manufactured for numerous applications. The process begins
with a rotational molding machine with attached spindles. The spindles
support the molds in which the plastic material is contained. The molding
machine moves the molds past loading, heating and cooling areas. From
start to finish, there are four different stages that are completed in
anywhere from 15 to 90 minutes. The first stage, referred to as the charging
phase, is the loading and sealing of the material in the metal mold.
From there, the mold is heated to a specified temperature while revolving
on the vertical and horizontal axes of the spindles. Phase three is a
cooling stage that begins to solidify the plastic within the mold. The
mold is then reopened, and the solid plastic part is removed. For applications
that require additional strength, reinforcing ribs can be fabricated
into the part. Additives to make the part flame retardant, corrosion
resistant or static free can also be included in the plastic resin.
Common rotationally
molded plastics are cross-linked polyethylene (PE), high density
polyethylene (HDPE), linear low density polyethylene (LLDPE) and polyvinyl
chloride (PVC). PE is ideal for products that will be exposed to extremely
cold temperatures, as it has high impact strength in temperatures to
-20ºF. HDPE is able to withstand a wide variety of environmental factors,
making it highly useful in the agricultural and chemical industries.
LLDPE is a low-cost material that has a wide range of uses. PVC is used
for its flexible properties in applications, such as medical tubing,
bags and cases. Lighter materials are used more often in rotomolding,
making it less expensive than other methods, and making it cost effective
for sizeable production runs and prototypes. Examples of other rotomolded
products include football helmets, plastic
tanks, large trash containers and juice/pop bottles.
Rotational molding services have several advantages over blow
molding and injection
molding. The tooling in the rotomolding process
can be designed to undercut and core features in a part. This option
would be very costly in the blow molding process. Rotationally molded
plastic parts have thickness in outside corners, which is critical to
durability. This formation of thickness is inherent to the rotomolding
process, but not to the blow molding process. Rotational molding also
provides freedom of design that would be constrained by the process
and tooling of blow molding. Rotational molding does not require pressure
to be used, so the molds do not endure the same pressure as in injection
molding, and this makes the process less expensive.
There are many other advantages to the rotational molding process. While
being heated and rotated, the plastic resin adheres to the hot mold,
coating it very evenly and seamlessly, producing strong outside corners
with virtually no stresses. Rotomolding can
produce one-piece constructions. Complex parts can be formed without
any part assembly required. The
plastics used for rotomolds are
lightweight and relatively cheap. The low cost of the materials and
tooling makes rotational molding just as cost effective for producing
prototypes as it is for large production runs. A variety of finishes
and colors are available. Rotomolding is a versatile process that provides
durability to products.
Rotational Molding and Rotational Molding Services
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Rotational Molding
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Types of Rotationally Molded Plastics and Rotational
Molding
Cross-linked polyethylene
is an ideal material for rotomolded products that will be exposed to
extremely cold temperatures.
High-density polyethylene
(HDPE) offers high-flow molding and high molecular weight performance
in rotationally molded parts. Properly rotomolded HDPE products will
have interior gloss development, ductile cold temperature impact performance
and an off-gas odor that confirms the chemical cross-linking reaction.
Linear low density
polyethylene (LLDPE) provides superior fit and finish to rotationally
molded products. Rotomolded LLDPE products also have high impact, tensile
and dielectric strength.
Polyethylene (PE)
is a lightweight plastic that has a low modulus of elasticity. Rotationally
molded PE products are thick in desired places and have good impact
resistance.
Polyvinyl chloride
(PVC), also referred to as “vinyl,” has excellent
transparency, chemical resistance, long-term stability, good weatherability,
flow characteristics and stable electrical properties. PVC can be either
rigid or flexible.
Rotational moulding is the low pressure process used to create hollow plastic components.
Rotationally molded fuel tanks
are seamless polyethylene (PE) tank structures that retain molded-in
logos, warnings, serial numbers and other full color graphics when exposed
to salt water, sunlight, solvents, cold weather and other severe conditions.
Rotomolding is the four-step process used to make hollow plastic components.
Rotomolds are machines used to make hollow, one-piece plastic parts.
Rotational Molding Terms
Blow Molding (http://www.iqsdirectory.com/blow-molding/)
– A common process used to form hollow, thermoplastic shapes, such
as bottles and containers. Two general types of blow molding are extrusion
and injection blow molding.
Chemical Cross Linking – The
process in which individual polymer particles are joined together by a
molecular bond.
Chemical Resistance – The ability
of a material to withstand various chemical agents. Plastic is capable
of enduring many of these chemicals, making it very useful for holding
tanks and other containers.
Corrosion – The oxidation and
deformation of a material, such as the rusting of iron, due to a chemical
reaction.
Cycle Time – The time it takes
from the first stage of rotational molding, in which the plastic is loaded,
until the plastic completes its final stage and is removed from the mold.
Deflashing – The removal of
unwanted material from a molded product, especially from the areas where
parting lines of the mold may have caused excess material to be formed.
Density – A significant parameter
for polyethylene (PE) that affects the properties, such as stiffness and
impact strength, of the end product.
Elasticity – The ability of
a material to return to its original form after stress has been applied
and quickly removed.
Fusion Temperature – The temperature
at which the plastic resin melts and begins to adhere to the surface of
the mold.
Grind Ability – The ability
of a plastic to be ground into a fine powder. Most plastics are ground
prior to being loaded into the mold.
Impact Resistance – The measure
of the ability of a plastic to withstand fracture by shock.
Plastic – A generic name for
semi-synthetic or synthetic materials that can be extruded or molded into
films or objects. Plastic
materials are also used for coatings and adhesives.
Polymer – A chain of molecules
that is formed by the bonding of individual repeating units (monomers).
Pour Ability – The measure of
the speed of a plastic powder when poured through a funnel. For a plastic
powder to be acceptable for rotomolding, it must be capable of flowing
at least 185 grams/minute.
Resin – Any of various semisolid
or solid natural organic materials that are usually translucent or transparent.
Resins are mostly utilized in plastics, adhesives and coatings.
Spindles – The “arms”
of the rotational molding machine that are responsible for moving the
molds between different stages. Spindles also spin on the horizontal and
vertical axes to create a uniform filling within the mold.
Thermal Stability – The ability
of a resin to withstand specified temperatures. Less thermally stable
materials can be rotomolded only under controlled conditions with extreme
care.
Thermoplastic – A material that
will soften when repeatedly heated and cooled. Examples of thermoplastics
include polyethylenes, polypropylene (PP), vinyl and nylons.
