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This article will take a detailed look at the manufacturing
of plastic rods.
We will go in-depth on topics such as:
What is a Plastic Rod?
Types of Plastic Rods
Applications and Benefits of Plastic Rods
And much more…
Chapter 1: Principle of Plastic Rods
This chapter will discuss the definition of plastic rods, their
function, and the materials used in manufacturing.
What is a Plastic Rod?
A plastic rod is a solid plastic shape made by the process of
plastic extrusion or plastic co-extrusion. These have a contrast
of plastic tubing and hollow plastic profiles. Plastic rods are
found in various industries, including aerospace, electronics,
petrochemicals, marine, and transportation.
They are often used as raw materials in these industries in
order to be machined into parts for seals, gaskets,
corrosion-resistant pieces, bearings, static control, sleeving,
insulation, and others.
They are also used in the construction sector and in commercial
businesses, all with the aim of serving applications that are
related to the structural support of industrial equipment and
the displays of point of purchase.
Manufacturing Plastic Rods
Plastic rods are made by the processes of plastic extrusion or
plastic co-extrusion. These processes are described in detail
Plastic Extrusion Process
The main process performed in the production of plastic rods is
called the plastic extrusion process. In this process of the
extrusion of plastics, the raw compound material usually begins
in the form of nurdles. These are small beads, often called
resin, that are gravity-fed from a top-mounted hopper and then
into the barrel of the extruder. Colorants and UV inhibitors in
the form of pellets or liquid are placed in as additives, and
they can be mixed together with the resin prior to arriving at
The plastic extrusion process has much in common with the
plastic injection molding process from the point of the extruder
technology, but it differs in the sense that it is a continuous
process. The process of pultrusion can offer many similar
profiles in continuous lengths, usually with reinforcement. This
is achieved by pulling the finished product out of a die instead
of extruding the polymer melts through the die.
The material then enters through the feed throat, which is an
opening near the rear of the barrel, and comes into contact with
the screw. This rotating screw commonly rotates at 120rpm, and
its job is to force the plastic beads forward into the heated
The temperature required for extrusion is rarely equal to the
set temperature of the barrel due to effects such as viscous
heating. In most contained processes, a heating profile is set
for the barrel. In this barrel, three or more independent
PID-controlled heater zones do the job of gradually increasing
the temperature of the barrel from the rear. This rear is where
the plastic enters towards the front. This allows the plastic
beads to melt gradually as they are pushed through the barrel,
and it also helps in lowering the risk of overheating, which may
result in the degradation of polymers.
More heat contained in the process is contributed by the intense
pressure and friction that takes place inside the barrel.
Generally, if an extrusion line is working on certain materials
fast enough, the contained heaters can be shut off, and the
temperature of the melt can be maintained by the pressure and
friction inside the barrel. In a large number of extruders,
cooling fans are present to keep the temperature below a set
value if too much heat is generated. Cast-in cooling jackets are
put into use if the process of forced air cooling is
The molten plastic leaves the screw at the front of the barrel
and travels through a screen pack headed to remove any
containment in the melt. The screens are made stronger by
reinforcing them with a breaker plate, which is a thick metal
puck drilled through with many holes. The reinforcement is
performed since the pressure at this point can exceed 5000 psi
or 34MPa. The breaker plate assembly or the screen pack also
does the work of creating back pressure in the barrel. This back
pressure is needed for the uniform melting and proper mixing of
The amount of pressure generated can be tweaked by varying the
composition of the screen packs, which involves the number of
screens contained, their wire weave size, and other parameters.
The rotational memory of the molten plastic is also eliminated
by the combination of the screen pack and the breaker plate.
This combination also further creates longitudinal memory.
Molten plastic enters the die after it passes the breaker plate.
This die then gives the final product its profile. It must be
designed so that the molten plastic will evenly flow from a
cylindrical profile to the profile shape of the product. The act
of an uneven flow can result in the production of a product that
has unwanted residual stresses at certain points in the profile,
which can cause warping upon cooling. A numerous number of
shapes can be created but with the restriction of the continuous
The end product is then cooled, usually by pulling the extrudate
through a water bath. Because plastic is a very good thermal
insulator, it is difficult to cool down quickly. Plastic
conducts its heat away 200 times more slowly than steel. A
sealed water bath contained in a tube or extrusion line is acted
upon by a carefully controlled vacuum so as to keep the newly
formed, molten tube or pipe from collapsing.
In some products, such as plastic sheeting, the process of
cooling is achieved by pulling through a set of cooling rolls.
For very thin sheeting and films, air cooling can be made very
effective as an initial cooling stage as in blown film
extrusion. The plastic extruders are also used to reprocess
recycled plastic waste and other raw materials after sorting,
blending, and cleaning. The material is often extruded into
filaments that can be cut up into pellet stock or beads to be
used further in processing.
Plastic Co-Extrusion Process
Plastic rods are not actually always made completely from
plastic. In some situations, they can be co-extruded with other
non-plastic materials like metals. Co-extrusion is thus an
altered process of extrusion in which a single product is made
from two or more different materials mixed together. For one to
be able to achieve this, multiple extruders which are pointed at
a single die do the work of melting the polymers which are
intended to make the product.
After these become molten, the materials are forced into the die
at an even volume and pace. When the materials fill it out in
layers, they enter the die at the same time. The goal of
co-extrusion is to produce a product that contains properties
and qualities that it cannot get from just the use of one
In order to lower material costs or to strengthen the core of
the rod, manufacturers often choose to co-extrude a plastic rod
with a different type of plastic or other material. In
applications that require little structural strength, the issue
of low-cost co-extrusion materials is usually considered.
In areas where better structural support is needed, the
component metal is usually used as the material that fills the
rod. Aside from the noted qualities, the plastic co-extrusion
process also aims to increase resistance in wear and the
permeability of oxygen.
Types of Extruders
There are various designs of extruders available in the market
nowadays to carry out the extrusion processes. Depending on the
operation mode, these can be subdivided into two types:
continuous extruders and discontinuous extruders. The
distinction between the two is the part that makes the material
move. Continuous extruders contain rotating parts, while
discontinuous extruders contain reciprocating parts. Continuous
extruders can further be divided into two groups, which are
screw extruders and drum or disk extruders.
Single Screw Extruders
These are the most common continuous extruders due to their
advantages of low cost, toughness, simple design, high
performance, and reliability. A standard single screw extruder
contains three geometrically varying zones. The contained zones
are the feed zone, metering zone, and the compression zone.
These zones are formed by constant pitch, but vary the depth of
The depth of the screw channel experiences a linear decrease
from the feed zone towards the metering zone. This action causes
the compression phenomena. For the same screw length and
diameter, zone length and maximum or minimum channel depths may
vary. Hence, different screw profiles are possible. The
environments inside the extruder may also depend on factors such
as screw profile, screw speed, and set temperature. These
factors affect the heat dissipation, local heat conduction,
velocity of the profile, and the residence time inside the
These extruders are classified as continuous extruders, but they
do not use screws to convey the material. Disk extruders use
disks or drums to facilitate the extrusion process. For this
reason, disk extruders are also named screwless extruders. Most
versions of disk extruder are operated based on viscous drag
This type of extruder utilizes a rotating drum and barrel to
perform the extrusion process. In drum extruders, the polymeric
material is fed into the annular space between the barrel and
the drum. As the drum rotates, the material is carried along the
circumference of the barrel. As one full rotation is yet to be
completed, there is a wiper bar that does the function of
scrapping the melt from the drum and directs the flow to the
exit. This flow is later directed to the extruder die.
Multi Ram Extruder
Multi ram extruders operate in a continuous manner. Other
designs of the extruder have four plunger cylinders. Of these
cylinders, two are for plasticizing and the other two are for
pumping. The cylinders used for pumping are connected by an
intricate shuttle valve.
Thermoplastics and Thermosets
The plastic formulas used in the extrusion of plastic rods are
wide and many. But despite this fact, most of them fall into two
groupings, thermosets and thermoplastics. Of these two,
thermoplastics are for the majority of plastics. These
thermoplastics consist of plastics that can soften and melt when
they experience heating or that can be reheated and hardened
They can also be heated and remolded again and again. This
category includes plastics such as PVC, ABS, polythene,
polypropylene, polycarbonate, and polystyrene. Thermosets can
also become molten when heated, and they can also harden when
cooled, but unlike thermoplastics, thermosets cannot be
successfully reheated, reshaped, or re-hardened. Thermosets
examples include polyesters, phenolics, epoxies, and silicones.
Because of these qualities of thermosets, they lack an advantage
Manufacturing with Thermoplastics
Usual manufacturing methods of thermoplastics include injection
molding, extrusion, casting, pultrusion, machining, grinding,
and the process of welding. Stock shapes like rods, sheets,
films, tubes, and pipes are readily available for secondary
operations. Raw materials are also provided in materials
including plastic resin, powder, gel, and liquid form. Polymeric
resins make up the majority of thermoplastics.
Polymeric resins contain long chains of several smaller monomers
that are held together by covalent bonds. Additional polymers
and condensation polymers are the two types of thermoplastics.
Plastics that are found in the additional polymers group are
those types of plastics that make covalent bonds without the
loss of molecules or even the loss of atoms in the reaction.
Condensation polymers are polymers that always lose a molecule
during the bonding process, like water. In these two types of
groups, the materials can be broken down into monomers, binders,
intermediates, base polymers, elastomers, and materials of
rubber, all based on their chemical composition and the
formation of the bond. These thermoplastics can also be divided
by their specific properties.
Despite using polymerized materials only, the manufacturers can
resort to adding powders, fibers, plasticizers, and ceramics.
This is done in order to improve or alter the features of a
plastic material. They play a significant role in the processing
and fabrication of thermoplastics.
Thermoplastics are resins that retain solidity at room
temperature, become soft when heated, and eventually become
fluid as a result of the process of crystal melting or crossing
the glass transition temperature. In the processing of
thermoplastics, there is no chemical bonding involved, and
thermoplastics can be poured into a mold to cool and solidify in
their desired shape. They can also be reheated, recycled, and
remolded without affecting the properties of the material.
Such materials are used in processes that include extrusion,
thermoforming, and injection molding. These types of plastics
often have the ability to resist shrinking and at the same time
offer good elasticity and better strength. More benefits include
good adherence to metals and a high-quality aesthetic finish.
These types of plastics can be recycled, and they can also be
reshaped with little impact on the properties of the material.
They also employ good electrical insulation and resist chipping,
at the same time enhancing their anti-slip properties.
Despite all these pros, they also have some cons, including the
fact that they are not good for all applications due to their
property of softening when heated. They are also more expensive
than thermosetting polymers.
When purchasing thermoplastics, one should consider the fact
that these thermoplastics offer a wide range of different
crystalline structures and densities. It is also ideal for one
to note and understand the properties of a given plastic rod
with regard to the final product or the area of application.
In selecting the right thermoplastic for a certain specific
application, one should understand that additives, raw materials
supply, and the manufacturing process are important influencing
factors. For depth considerations, one should look into
electrical, physical, mechanical, and optical specifications
that, at the same time, include the issue of the melting point,
dimensions, and the contained flexibility.
Manufacturing with Thermosets
These types of plastics are also called thermosetting resin or
thermosetting polymers. They are usually liquid at room
temperature, and they are able to harden as they are heated or
when a chemical is added to them. Thermoset plastics are
typically produced using reaction injection molding (RIM) or a
process called resin transfer molding (RTM), and the thermosets
form permanent chemical bonds during the curing process.
These chemical bonds which are formed between the monomer chains
within the material are called cross-links, and they do the job
of holding the contained molecules in place. They also change
the nature of the material, thus preventing it from melting and
also preventing it from returning to a liquid state. Thermoset
plastics are set into a form that is specific once they are
heated. But the process of overheating may cause them to degrade
without entering a fluid phase.
These thermoset plastics are ideal for use in situations where
heat is a factor; examples include electronic housing,
electronic appliances, and chemical processing equipment. This
is also due to their greater structural integrity and their
ability to resist both heat and chemicals found in these
thermosets. Thermosets are also able to resist deformation and
the effects of impact. Some general thermoset examples include
epoxy resins, phenolics, and polyimide. These examples are often
used in composites.
Thermosets have some advantages, including: being able to be
molded with a different range of tolerances, typically being
cheaper compared to components fabricated from metals, having a
cheaper setup and tooling cost compared to thermoplastics, and
having a higher strength-to-weight ratio. But despite all these
pros, they come with some cons, including the inability to be
reshaped or remolded and the fact that thermosets cannot be
Secondary Processes for Plastic Rods
Although this is not needed in most cases, some manufacturers
choose to further fashion their plastic rods through secondary
ways such as drilling, painting, deburring, coating with powder,
labeling, industrial finishing, and notching. These plastic rods
can be clear or can come in different colors, which also include
Manufacturers love the idea of working with extruded plastic
rods due to the versatility and the plastic extrusion’s wealth
of material choices. Plastic rods are an ideal choice for one
looking for inexpensive, quick, and durable products.
Chapter 2: Types of Plastic Rods
Despite the different materials used to extrude or co-extrude
plastic rods, all these plastic rods share some of the uncommon
properties of materials made from plastic. Some of these
properties include low density, the inability to conduct, low
porosity, greater structural integrity, resistance to corrosion,
resistance to heat, and malleability.
Manufacturers have the ability to produce different plastic rods
containing different chemical combinations and also being made
from different materials. Due to this, there is room for the
creation of plastic rods which have particular properties for
Acetal Plastic Rods
This type of plastic rod is made up of acetal, also referred to
as polyoxymethylene. This is a high-strength, semi-crystalline,
and low friction engineering plastic with low absorption in
moisture. This type of plastic rod has excellent wear properties
and also excellent abrasion properties in both wet and dry
environments. The acetal plastic rod is also easy to machine,
and acetal enables an outstanding choice for applications that
require tight and complex tolerances.
Acetal plastics are resistant to chemicals that are included in
some fuels and solvents. Most of the applications of acetal
plastic rods include manifolds, bearings and bushings, food
processing and packaging machinery parts, wear pads, wear
strips, and pump and valve parts.
Acrylic Plastic Rods
This type of plastic rod is made up of acrylic, which is also
known as Plexiglas. This type of plastic is strong, stiff, and
available in clear and other colors. Its glass-like properties
include its clarity, transparency, and brilliance, but it is
half the weight and more times the impact resistance of glass.
Some applications of acrylic plastic rods include indoor and
outdoor signs, architectural glazing, safety shields, sneeze
guards, and POP displays.
Polyimide Plastic Rods
This type of plastic rod is made up of polyimide, which is an
extremely high temperature- and creep-resistant plastic material
mostly used in high heat environments. And in these
environments, thermoplastic materials are due to lose their
plastic mechanical properties and as a lightweight metal
Polyimide plastic rods have very long-term performance at
cryogenic temperatures and also up to 500 °F (260 °C), thus
making them a common choice for use in aerospace and other
industrial applications. They are also used in chip test
sockets, wafer clamping rings, semiconductors, and material
handling machinery, and also they are put to use in valve seats
High-Density Polyethylene Plastic Rods
High-density polyethylene is a chemically resistant, strong,
durable, lightweight plastic material that is ideal for a
variety of applications. High-density polyethylene plastic rods
are easy to fabricate and weld using thermoplastic welding
equipment, thus making them excellent for use in fabricated
water tanks and chemical tanks.
High-density polyethylene plastic rods are also widely used in
applications which include the cutting of boards for food
preparation, marine constructions, orthotics and prosthetics,
water pipe flanges, and outdoor and indoor playground systems.
Nylon Plastic Rods
Nylon rods are made up of nylon, which is a stiff and strong
engineering plastic containing outstanding properties in wear
and bearing. The nylon plastic rod is usually used to replace
metal bearings and brushes, resulting in the elimination of the
need for external lubrication, reducing the weight of the part,
dampening operating noise, and decreasing the wear on mating
Some other applications of the nylon plastic rod include wear
pads, gears, and packaging machinery parts.
Polyetheretherketone Plastic Rods
Polyetheretherketone rods are also referred to as PEEK plastic
rods. They contain high-performance engineering plastic that has
outstanding resistance to harsh and aggressive chemicals. It
also has a very high mechanical strength and stability in its
dimensions. The PEEK plastic rod offers hydrolysis resistance to
steam, seawater, and water in general.
The PEEK plastic rod has the ability to maintain certain
stiffness at temperatures of a high magnitude, and it is also
suitable for continuous use at temperatures as high as 338 °F
(170 °C). Some of the applications of the PEEK plastic rod
include aerospace parts, seals, medical instrument parts, food
processing machinery components, bushings, bearings, and pump
and valve components.
Polycarbonate Plastic Rods
Polycarbonate is a transparent, stiff, and strong thermoplastic
with outstanding impact resistance even at low temperatures. The
polycarbonate plastic rod is easy to machine and contains
excellent stability in its dimensionality.
Some of its applications include indoor and outdoor signs, POP
displays and graphic holders, skylights, architectural glazing,
face shields, semiconductor machinery components, machine
guards, and transparent manifolds.
Polypropylene Plastic Rods
The polypropylene plastic rod is a chemically resistant plastic
rod with excellent aesthetic properties at a cost that is low.
The polypropylene plastic rod is easy to weld using
thermoplastic welding equipment, and it is also often fabricated
into water and chemical tanks.
Some of the applications for the polypropylene plastic rod
include rigid outer prosthetic sockets and also in lower and
upper extremity orthoses.
Polytetrafluoroethylene Plastic Rods
The polytetrafluoroethylene plastic rod is a soft, low friction
fluoropolymer rod that has outstanding resistance to weathering
and chemicals. The polytetrafluoroethylene plastic is stable at
temperatures of a magnitude of up to 500 °F (260 °C), and it is
also used in temperate environments.
Polytetrafluoroethylene plastic also has very many excellent
properties in electrical insulation. Some applications of the
polytetrafluoroethylene plastic rod include the use in pump
parts, manifolds, semiconductors, scientific equipment, seals,
Polyvinyl Chloride Plastic Rods
This type of plastic rod, also referred to as PVC plastic rods,
is strong and stiff and is of a low-cost plastic material that
is easy to fabricate and easy to bond using solvents and
adhesives. The polyvinyl chloride plastic rod is also easy to
weld using thermoplastic welding equipment. Some applications of
the PVC plastic rod include valve and pump housings, cabinets,
and welded chemical tanks.
Chapter 3: Applications and Benefits of Plastic Rods
This chapter will discuss the applications and benefits of
Benefits of Plastic Rods
Each type of plastic grouping contains different pros and cons.
For example, thermoplastics are generally easier to mold and are
faster to produce compared to thermosets. Aside from this,
thermosets tend to have components of superior strength. And
unlike thermoplastics, they are able to retain their strength
when they are heated.
For further identification, each plastic material is able to
offer different qualities and attributes in relation to how the
manufacturer may want it. Taking, for example, PVC, this
component has a higher resistance to heat, chemicals, and fire,
and it is most popular in the building of exteriors, metal
anodizing, sewage treatment, and chemical processing.
Acetal plastic rods contain very low water absorption ability
and are resistant to chemicals, but despite this, they are
relatively weak and susceptible to heat. Because of these
qualities, they are suitable for food processing applications
that do not require high heat resistance or strength. The
manufacturers that make flexible and scratch-resistant products
are likely to use plastics which include HDPE or acrylic. These
two types of plastics are valued for the ease with which they
can be manipulated.
Applications of Plastic Rods
Plastic rods are found in various industries, including
aerospace, electronics, petrochemicals, marine, and
transportation. They are often used as raw materials in these
industries so as to be machined into parts for seals, gaskets,
pieces that are corrosion resistant, bearings, static control,
sleeving, insulation, and other contained acts. They are also
used in the construction sector and in commercial businesses,
all with the aim of serving applications that are related to the
structural support of industrial equipment and the displays of
point of purchase.
A plastic rod is a solid plastic shape made by the process of
plastic extrusion or plastic co-extrusion. Despite the different
materials used to extrude or co-extrude plastic rods, all these
plastic rods share some of the uncommon properties of materials
made from plastic. Some of these properties include their low
density, inability to conduct, low porosity, greater structural
integrity, resistance to corrosion, resistance to heat, and
Plastic channels are plastic products that have linear
extruded profiles. They have a constant cross-sectional shape
across their axis. They are long and narrow structures, and
their depth is relatively short. These products serve a
variety of functions and uses...
Plastic extrusion, also known as plasticating extrusion, is a
continuous high volume manufacturing process in which a
thermoplastic material -- in a form of powder, pellets or
granulates -- is homogeneously melted and then forced out of
the shaping die by means of pressure...
Plastic trim products are extruded linear profiles that can be
made to any length. Because of its ability to attach, hold,
and seal, plastic trim has many applications. Plastic, HDPE,
LDPE, butyrate, PVC, acrylic, and...
Nylon tubing, also known as polyamide tubing, is a type of
tubing made from polyamide resin, which has a strong
resistance to abrasion. It is used in high-pressure and
Plastic fabrication is the process of designing,
manufacturing, and assembling a product made out of plastic
material or composites that contain plastic. There are
numerous plastic fabrication methods known today, considering
the wide variety of products made out of plastic...
Plastic materials are objects artificially made from organic
compounds called polymers along with other additive
components. They possess excellent formability, making them
extremely versatile for many different fabrication and
Plastic tubing is a form of tubing that is manufactured from a
mixture of a polymer with a variety of chemicals to form a
material that can be solid or flexible. Since its first use in
the 1950‘s, plastic tubing has revolutionized industrial
processes and has found a use in a wide variety of
Poly tubing is a highly flexible, lightweight, and durable
tubing that is produced from polyethylene, a polymer that is
made from the polymerization of ethylene. It is a very
versatile form of tubing that has break and crack resistant
PVC is a tough chemically resistant synthetic polymer of vinyl
chloride used especially for making pipes, films and
electrical insulation. It is made by polymerizing vinyl
Silicone tubing is a very tough elastomer that exhibits high
strength, flexibility, and resistance. Silicone tubing can be
stretched without tearing and is highly versatile. It cannot
be weakened with repeated bending and twisting due to...