WHEATON Technical Data - page 15

WHEATON
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Technical Data, Plastic
Plastic Manufacturing Terminology
Blow Mold
Cavity that receives the Preform, which will be blown into the desired shape.
Blow Pin
Used in Extrusion Blow Molding. Hollow tube that pierces Preform and introduces air to
blow Preform into shape of Blow Mold.
Cavity
That part of the mold that contains the reverse image of the product being formed.
Cold Runner
Flow channel for heat-softened polymer that goes from the Plastifier to the mold cavities.
Polymer in the flow channel is cooled with shaped parts in cavities and is later removed,
reground, and reused.
Core
That part of a mold that allows the internal shaping of a product such as the internal
threads of a closure.
Core Rod
Used in Injection Blow and Injection Stretch Blow Molding. Used in conjunction with a
Preform Mold to manufacture a Preform. The Preform is formed around the Core Rod
creating a hollow tube, which will then be transferred to a Blow Mold where air will be
introduced forcing the Preform to take the shape of the Blow Mold cavity.
Extrusion Blow Molding
A molding process whereby heat-softened polymer is forced into the shape of a hollow
tube. While still soft, a mold closes around the tube, pinching the top and bottom of the
tube closed. A Blow Pin is introduced, and air is forced through the pin forcing the tube
to take the shape of the Blow Mold cavity.
Flame Treating
A method of rendering inert thermoplastic objects receptive to inks, lacquers, paints,
adhesives, etc. in which the object is bathed in an open flame to promote oxidation of
the surface of the article. Polyolefins (HDPE, LDPE, PP, etc) are primarily those polymers
that are flame treated.
Flash
Extra plastic attached to molded ware along the parting line, which must be removed
before the part can be considered finished.
Gate
Used in Injection, Injection Blow and Injection Stretch Blow Molding. The orifice through
which the heat-softened polymer enters the cavity.
Hot Runner
Flow channel for heat-softened polymer, which goes from the Plastifier to the mold
cavities. Polymer in the flow channel is kept softened so there is no runner material to
grind up and reuse.
Hopper
Conical feed reservoir into which polymer pellets are loaded. These pellets then fall into
a heated barrel (Plastifier), sometimes through a metering device.
Injection Blow Molding
A molding process in which heat-softened polymer is injected from a Plastifier into a
mold cavity creating a Preform, which is then transferred to a Blow Mold where air is
blown into the Preform, forcing it to take the shape of the Blow Mold cavity.
Injection Molding
A molding process whereby a heat-softened polymer is injected from a Plastifier into a
relatively cool cavity, which gives the article the desired shape.
Injection Stretch Blow Molding
A molding process whereby Preforms are introduced into a cavity, stretched axially by
a Stretch Rod, and then blown circumferentially to the shape of the Blow Mold cavity.
Melt Index
The amount, in grams, of a thermoplastic resin, which can be forced through
a 0.0825 inch orifice when subjected to 2160 gms. force in 10 minutes
at 190°C.
Mold
Contains the cavity or cavities of a desired part in which a heat-softened polymer is
shaped.
Mold Seam
A line formed at the point of contact of the Mold halves.
Neck Ring
Part of the mold assembly that forms the neck and finish of a container.
Nozzle
Hollow cored orifice that is screwed into the extrusion end of the Plastifier. The nozzle is
designed to form a seal under pressure between the Plastifier and the Mold or Runner
system. The front end of a nozzle may be either flat or spherical in shape.
Plastifier
Assembly whereby polymer pellets are fed from a Hopper into a barrel where they drop
onto a turning screw which forces the pellets forward. Heater bands wrapped around
the barrel melt the pellets as they are forced forward along the inside of the barrel. The
molten polymer is then forced out the end of the barrel through the nozzle.
Preform
Used in Blow Molding processes. Heat-softened polymer is formed into a shape similar
to a thick test tube with neck threads. This tube is subsequently inflated while inside a
Blow Mold to create the shape of the desired article.
Regrind
A thermoplastic from a processor’s own production that has been reground or re-
pelletized after having been previously processed by molding.
Release Agent
A lubricant that facilitates molding.
Stretch Rod
Used in Injection Stretch Blow Molding. A rod that is introduced into the Preform to
stretch it in an axial direction prior to the Preform being blown into the shape of the
cavity.
Swingplate Injection Molding
A molding process where a heat softened polymer is injected through a stationary plate
and then through a second metal plate or “swingplate”, through cores mounted on the
other side of the swingplate, and into cavities in a third plate. The polymer flows out of
and around the cores and filles the cavities. Once the cavities are filled, the third plate
moves away from the cores, leaving the molded parts on the cores. The swingplate then
swings over to a secondary station where the cold runner and molded parts are removed.
While this is happening, another swingplate moves from the secondary station to the first
station and new parts are molded.
Thermoplastic
Material that will repeatedly soften when heated and harden when cooled.
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