For any designer and engineer working in product development, it is necessary to be familiar with the manufacturing options available today and the new developments on how parts will be made tomorrow.
Plastics are the most common materials for producing end-use parts and products, for everything from consumer products to medical devices. Plastics are a versatile category of materials, with thousands of polymer options, each with their own specific mechanical properties.
Types of Plastics
1) Thermoplastics:
Thermoplastics are the most commonly used type of plastic. The main feature that sets them apart from thermosets is their ability to go through numerous melt and solidification cycles without significant degradation.
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| Acrylic |
Common materials of Thermoplastics: a) Acrylic (PMMA)
Poly(methyl methacrylate), also in simple terms Transpernt plastics. Products include lens, LCD Screens Nail enamls.
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| Acrylonitrile butadiene styrene (ABS) |
b) Acrylonitrile butadiene styrene (ABS) Acrylonitrile
Butadiene Styrene (ABS) is an opaque thermoplastic. Acrylonitrile Butadiene
Styrene (ABS) is an opaque thermoplastic. They can be heated to their melting
point, cooled, and re-heated again without significant degradation. Instead of
burning, thermoplastics like ABS liquefy which allows them to be easily
injection molded and then subsequently recycled.
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| Polyamide |
c) Polyamide (PA) Polyamides occur both naturally and artificially. Examples of naturally
occurring polyamides are proteins, wool and silk. Artificially made polyamides
can be made through step-growth polymerization or solid-phase synthesis
yielding materials such as nylons, aramids, and sodium poly(aspartate).
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| Polylactic acid |
d) Polylactic acid (PLA) PLA
is a Food and Drug Administration (FDA) approved polymer for use a food contact
material. It can be used as food packaging polymer for short shelf life
products such as fruit and vegetables.
e) PC
is commonly used for plastic lenses in eyewear, in medical devices, automotive
components, protective gear, greenhouses, Digital Disks (CDs, DVDs, and
Blu-ray), and exterior lighting fixtures.
f) Polyether ether ketone(PEEK)Used in
various fields such as for semiconductors, liquid-crystal production equipment
and medical devices.
g) Polyethylene (PE). Applications
of Low Density Polyethylene (LDPE) Packaging – Thanks to its low cost and good
flexibility, LDPE is used in packaging industry for pharmaceutical and squeeze
bottles, caps and closures, tamper evident, liners, trash bags, films for food
packaging (frozen, dry goods, etc.), laminations.
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| Polypropylene (PP) |
h) Polypropylene (PP) Polypropylene
(PP) is one of the most commonly used thermoplastics in the world.
Polypropylene uses range from plastic packaging, plastic parts for machinery
and equipment and even fibres and textiles. Syringes, medical
vial, Petri dishes, pill containers, specimen bottles.
i) Polyvinyl chloride
(PVC)
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| Polyvinyl chloride (PVC) |
2) Thermosetting
Plastics
Thermosetting plastics (also referred to as thermosets) remain in a
permanent solid state after curing. Polymers in thermosetting materials
crosslink during a curing process that is induced by heat, light, or suitable
radiation. This curing process forms an irreversible chemical bond.
Thermosetting plastics decompose when heated rather than melting, and will not
reform upon cooling.
In
general, thermoset products are made through liquid molding processes. The
polymers and other agents are fed into tanks or barrels, where they are heated
to a liquid state and mixed. Then the liquid polymers and other agents are
injected into a mold cavity. As the material cools and hardens to the
configuration of the cavity, it goes through a curing process where the
polymers cross-link together. That process forms an irreversible chemical bond
that prevents the risk of melting, softening or warping when or if the finished
product is subjected to high heat or corrosive environments. This makes
thermosets perfect for high-heat applications and outdoor use.
Common Materials used in Thermosetting plastic:
Cyanate ester
Epoxy, Polyester
Polyurethane
Silicone Vulcanized rubber
Advantages of Thermoplastics
Thermoplastic materials are
suitable for recycling since they are easily melted.
Disadvantages of Thermoplastics
When subjected to adequate
heat, the material will re-liquefy, making them less suitable for uses where
the subjection of sustained heat is expected.
Types of Manufacturing
Processes in Plastic Industry
3D printer: This printer is used to construct three dimensional products from cad machine. The design is first created using a CAD software. It can be done in a variety of processes in which material is deposited, joined or solidified under computer control. 3D printing have increased to the point that some 3D printing processes are considered viable as an industrial-production technology. Small prototypes or models of logo shapes or of any other design can be produced for presentation purposes.
CNC Machining, Auto Cad
software.
CNC machining definition is that it is a subtractive manufacturing
process which typically employs computerized controls and machine tools to
remove layers of material from a stock piece. CNC machining process are limited
as the tooling creates curved corner sections. (https://youtu.be/8CSwOebmb0A)
Polymer Casting: The
polymer solution casting process utilizes a mandrel, or inner diameter mold,
that is immersed in a tank of polymer solution or liquid plastic that has been
specifically engineered for the process. Due to a combination of thermal and
frictional properties, the polymer solution then forms a thin film around the
mold.
Rotational Molding : Rotational
Molding involves a heated hollow mold which is filled with a charge or shot
weight of material. It is then slowly rotated, causing the softened material to
disperse and stick to the walls of the mold. https://youtu.be/jrihIWS6oVI
Vacuum Forming : Where
a sheet of plastic is heated to a forming temperature, stretched onto a
single-surface mold, and forced against the mold by a vacuum. This process can
be used to form plastic into permanent objects such as turnpike signs and
protective covers. https://youtu.be/x_BDgtAM3Ng
Injection Molding : Injection molding is a method
to obtain molded products by injecting plastic materials molten by heat into a
mold, and then cooling and solidifying them. The method is suitable for the
mass production of products with complicated shapes, and takes a large part in
the area of plastic processing.
Extrusion : Plastics extrusion is a
high-volume manufacturing process in which raw plastic is melted and formed
into a continuous profile. Extrusion produces items such as pipe/tubing,
weather stripping, fencing, deck railings, window frames, plastic films and
sheeting, thermoplastic coatings, and wire insulation.
Blow Molding : This is a process used for manufacturing plastic products. In this method plastic is melted . When it is in liquid state it is poured into desired molds. Then compressed air is inserted into the molds. the plastic blows itself inside the cavity of the mold into a desired shape.This method is usually used to make containers like watering cans, toys.
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