Posted: January 31st, 2023

Plastic Manufacturing Process

Plastic Manufacturing Process
Introduction Plastics are known by almost everyone and are among the most used materials in the U.S yet few people realize their importance in the everyday life which means that they are taken for granted. They are applicable in the pen used for writing, clothing, wrapping food or even the chairs used for seating. This makes it difficult to comprehend the fact that plastics have only existed for the previous one hundred years. However, they have made a huge impact on the quality of human life and have widened the range of products that one can access. The use of sophisticated technological processes and a greater level of technological understanding of plastics in manufacturing technology are responsible for this.
Plastics are strong, long lasting, lightweight, cheap and corrosion resistant materials containing great electrical and thermal insulation properties. Polymers have a wide versatility and diversity which make them applicable in a variety of products important in technological and medical advances and energy savings besides several other societal benefits.
This has led to a tremendous increase in the production of plastics. Plastics are present in almost every aspect of the day to day life for example in telecommunications, footwear, transport, packaging materials and even in clothing among others.
Virgin plastic polymers are usually utilized with an assortment of additives so as to improve performance, an example of which may include plasticizers that makes the material workable, inert fillers , for instance silica and carbon reinforces it while flame retardants, colorings, thermal and ultraviolet stabilizers are also used.
Even though the majority of these additives are essential, some of them are potentially toxic. tributyl and are a good examples. Current patterns of plastic usage are becoming a global concern in addition to the finite resources relied on for the production of plastic and the chemical effects of the different additives.
History of plastic manufacturing The development of plastics goes back to around 1860 at the time when a U.S company placed an offer of $10,000 for anyone able to design the best alternative for the natural ivory. John Wesley was one of the entrants and although he did not win the prize, went ahead to create a cellulose derivative to be used in the contest.
This product was later patented by the name Celluloid and became commercially successful.
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This product was later patented by the name Celluloid and became commercially successful.
It was used to manufacture a variety of products such as men’s collars and dental plates among others.
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It was used to manufacture a variety of products such as men’s collars and dental plates among others.
The next few decades that followed saw the development of more plastics and these included modified natural polymers such as rayon,
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The next few decades that followed saw the development of more plastics and these included modified natural polymers such as rayon,
the result of cellulose material.
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the result of cellulose material. A Belgian American chemist by the name Leo Hendrik Baekeland was the first to develop total synthetic plastic in the turn of the century and he later sold it as Baekelite. In 1920, plastic industry gained a breakthrough in terms of machinery and also the materials utilized. Herman Staudinger,
a German chemist came up with the idea that plastics were a combination of big molecules that are joined by strong chemical bonds.
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a German chemist came up with the idea that plastics were a combination of big molecules that are joined by strong chemical bonds.
This line of thought led to a lot of research on plastics and designing of new products in the period between the 1920s and 1930s.
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This line of thought led to a lot of research on plastics and designing of new products in the period between the 1920s and 1930s. Examples of these include methyl methacrylate commonly referred to as Plexigas or Lucite, nylon and polytetra floroethylne later in 1938 later marketed as Teflon in 1950.
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Wallace H.
Carothers of DuPont was the first person to prepare nylon but it was considered useless in its initial form due to the fact that it was sticky and had a small amount of structural integrity.
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Carothers of DuPont was the first person to prepare nylon but it was considered useless in its initial form due to the fact that it was sticky and had a small amount of structural integrity.
A chemist from DuPont by the name Julian Hill is the one who made the discovery that nylon can be used as fiber when drawn out due to the fact that it is strong and with a silky appearance.
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A chemist from DuPont by the name Julian Hill is the one who made the discovery that nylon can be used as fiber when drawn out due to the fact that it is strong and with a silky appearance.
Roy Plunkett unintentionally discovered that that Teflon was a material that was slippery, did not melt when exposed to extreme heat and was chemically inactive.
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Roy Plunkett unintentionally discovered that that Teflon was a material that was slippery, did not melt when exposed to extreme heat and was chemically inactive.
He did this when he was conducting an experiment on gaseous tetraflorethylene in order to prepare a refrigerant.
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He did this when he was conducting an experiment on gaseous tetraflorethylene in order to prepare a refrigerant.
Teflon is what is normally used for non-stick coating on various cookware.
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Teflon is what is normally used for non-stick coating on various cookware.
It was first used in World War II in the atomic bomb project to make gaskets inert to UF6 gas that is very corrosive and used in the purification of uranium isotopes.
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It was first used in World War II in the atomic bomb project to make gaskets inert to UF6 gas that is very corrosive and used in the purification of uranium isotopes.
Natural raw materials were in shortage in many countries at the time of World War II.
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Natural raw materials were in shortage in many countries at the time of World War II.
Germany ran out of latex and started using plastics instead leading to the development of synthetic rubber to act as an appropriate substitute.
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Germany ran out of latex and started using plastics instead leading to the development of synthetic rubber to act as an appropriate substitute.
When Japan joined the war, United States became unable to import the silk, natural rubber and lots of metals from most of the Far Eastern countries as it did before. Americans therefore turned to the plastic industry.
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When Japan joined the war, United States became unable to import the silk, natural rubber and lots of metals from most of the Far Eastern countries as it did before. Americans therefore turned to the plastic industry.
Nylon was utilized for fabrics while polyesters gained importance in manufacturing armour and other war resources.
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Nylon was utilized for fabrics while polyesters gained importance in manufacturing armour and other war resources. Production of artificial rubber increased and production of plastic continued even after cessation of war.
Plastics started replacing metals in things like safety helmets, machinery and in particular high-temperature devices.
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Plastics started replacing metals in things like safety helmets, machinery and in particular high-temperature devices. A German chemist by the name Karl Ziegler developed polyethylene in 1953 and an Italian chemist named Giulio followed by developing polypropylene in 1954.
These two scientists were later awarded the Nobel Prize in 1963 in the field of chemistry due to their research on polymers.
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These two scientists were later awarded the Nobel Prize in 1963 in the field of chemistry due to their research on polymers.
Polyethylene and polypropylene are the most commonly used plastics today.
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Polyethylene and polypropylene are the most commonly used plastics today.
Nowadays, the search for new plastics continues, scientists are experimenting on various ways of utilizing the existing plastics in addition to finding other materials can substitute plastics. Effect of plastic manufacturing of the U.S.
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Nowadays, the search for new plastics continues, scientists are experimenting on various ways of utilizing the existing plastics in addition to finding other materials can substitute plastics. Effect of plastic manufacturing of the U.S.
Plastics play a great role in various markets in the U.S which range from packaging and construction to the point of transportation,
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Plastics play a great role in various markets in the U.S which range from packaging and construction to the point of transportation,
furniture and furnishings, institutional and consumer products and electronics among others. Plastics have a significant effect on the United States economy being the third largest manufacturing industry.
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furniture and furnishings, institutional and consumer products and electronics among others. Plastics have a significant effect on the United States economy being the third largest manufacturing industry.
Research shows that U.S plastic industry provides employment to almost nine hundred thousand workers and gets more than $380 billion from annual shipments of plastics.
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Research shows that U.S plastic industry provides employment to almost nine hundred thousand workers and gets more than $380 billion from annual shipments of plastics. The number of plastic facilities has risen to almost 18,500 in the United States and the industry is represented in all states.
There are other alternative materials to plastics which are used today and glass, wood and polymers are good examples.
Plastic manufacturing processes Production of plastics is possible in four different categories which include getting monomer which is the raw material,
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Plastic manufacturing processes Production of plastics is possible in four different categories which include getting monomer which is the raw material, synthesizing the basic polymer, compounding that polymer to form a material applicable for fabrication and finally shaping or molding the plastic to give it its final appearance. Resins which were obtained from vegetable matter were historically used as raw materials and examples included cellulose from cotton, oils from seeds, furfural obtained from oat hulls and different starch derivatives. However, petrochemicals are used to produce most plastics today due to the fact that they are cheaper and are easily available. Since the worldwide supply of oil is becoming exhaustible, researchers are working to explore alternative sources of raw materials and examples include coal gasification.
Plastic production occurs in diverse stages, the first of which is polymerization which also occurs in either through condensation or addition.
The two phases can occur in solid, liquid or gaseous states.
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The two phases can occur in solid, liquid or gaseous states.
There are times when it happens at the intersection of two immiscible liquids where there is dissolving of the monomers.
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There are times when it happens at the intersection of two immiscible liquids where there is dissolving of the monomers.
Chemical additives can provide specific characteristics when used to produce plastics such as antioxidants to prevent degradation of the polymer from oxygen or ozone,
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Chemical additives can provide specific characteristics when used to produce plastics such as antioxidants to prevent degradation of the polymer from oxygen or ozone,
lubricants which reduce friction problems, antistatics, ultraviolet stabilizers that offer protection against weathering, pigments that give plastic their colors,
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lubricants which reduce friction problems, antistatics, ultraviolet stabilizers that offer protection against weathering, pigments that give plastic their colors,
plasticizers that improve on the flexibility of the polymer and flame retardants.
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plasticizers that improve on the flexibility of the polymer and flame retardants.
Normally, plastics are produced in the form of composites and this is done by adding some reinforcements to it and examples include carbon fibers and glass. These serve to improve on their strength and stability.
There is a type of composite known as plastic foam and this combines gas and plastic. A good example of this is foamed polystyrene used to make Styrofoam cups.
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There is a type of composite known as plastic foam and this combines gas and plastic. A good example of this is foamed polystyrene used to make Styrofoam cups.
There are different processes used to shape and finish plastics.
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There are different processes used to shape and finish plastics.
Compression molding has been used for decades to turn polymers into useful materials. It does this by giving plastic a particular shape with the application of pressure.
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Compression molding has been used for decades to turn polymers into useful materials. It does this by giving plastic a particular shape with the application of pressure.
A two piece mold is usually applied and one half of it is filled with plastic before the two halves are joined and the plastic is subjected to high pressure to enable it melt.
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A two piece mold is usually applied and one half of it is filled with plastic before the two halves are joined and the plastic is subjected to high pressure to enable it melt.
Extrusion is a common method used to shape plastics.
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Extrusion is a common method used to shape plastics.
An extruder is the device that forces softened plastic to go through a shaped die and they come out in a variety of forms such as wide, circular rod or tube, or even flat sheet.
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An extruder is the device that forces softened plastic to go through a shaped die and they come out in a variety of forms such as wide, circular rod or tube, or even flat sheet.
A screw is in charge of giving the driving force by providing the needed constant pressure. Every extrusion product has standard cross sections.
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A screw is in charge of giving the driving force by providing the needed constant pressure. Every extrusion product has standard cross sections.
This method has a variation which is extrusion blow molding whereby a plastic tube that is manufactured from extrusion undergoes sealing around the blowing tube before expanded with the help of compressed air to form the shape of a mold.
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This method has a variation which is extrusion blow molding whereby a plastic tube that is manufactured from extrusion undergoes sealing around the blowing tube before expanded with the help of compressed air to form the shape of a mold.
In injection molding, at least one extruder is responsible for forcing melted plastic inside a cold mold where it takes the required shape.
Injection blow molding is an adaptation of the injection molding method and this is important in making plastic pop bottles.
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Injection blow molding is an adaptation of the injection molding method and this is important in making plastic pop bottles.
It involves injection molding required for thick walled plastic tube and is done around a blowing stick prior to shifting to a blowing mold.
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It involves injection molding required for thick walled plastic tube and is done around a blowing stick prior to shifting to a blowing mold.
This tube is then reheated and air is passed down the blowing stick to enable it expand and take the shape of the mold.
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This tube is then reheated and air is passed down the blowing stick to enable it expand and take the shape of the mold.
There are other methods too that are used to shape and finish plastics and an example is calendaring responsible for the production of plastic sheets and transfer molding.
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There are other methods too that are used to shape and finish plastics and an example is calendaring responsible for the production of plastic sheets and transfer molding.
This involves forcing the softened plastic inside a mold with the help of a ram.
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This involves forcing the softened plastic inside a mold with the help of a ram.
The particular product being manufactured can greatly influence the manufacturing process to be used. There are processes that one can use at home while others require high tooling investment.
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The particular product being manufactured can greatly influence the manufacturing process to be used. There are processes that one can use at home while others require high tooling investment.
Low investment processes are generally slower because they are craft based compared to high investment processes.
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Low investment processes are generally slower because they are craft based compared to high investment processes.
It is important to know that the injection molding is only economically feasible if you are producing a very high output.
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It is important to know that the injection molding is only economically feasible if you are producing a very high output.
For example,
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For example,
the machine used for injection molding takes only forty seconds to transform safety granules in to safety helmet and this adds up to 2,160 helmets in 24 hours and 15,120 helmets weekly and 786,240 yearly which is a huge figure.
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the machine used for injection molding takes only forty seconds to transform safety granules in to safety helmet and this adds up to 2,160 helmets in 24 hours and 15,120 helmets weekly and 786,240 yearly which is a huge figure.
The fact that it is possible to share the tooling cost among many units makes the unit price relatively cheap. When it comes to small runs such as 5,000 products, injection molding is not cost efficient.
Fabrication, casting and rotational molding actually are inexpensive to set up but the making process is quite slow. With exception to plastic bags, injection molding is used to make the most plastic objects compared to other processes.
Various processes leave markings on the finished product: and injection molding is top among them. These marks are of two types; ones made by the sprue and those made by ejector pin.
Tail breaks off when liquefied plastic is driven into the molds and this marks where the sprue occurs.
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Tail breaks off when liquefied plastic is driven into the molds and this marks where the sprue occurs. The ejector pin markings are even and rounded and help while taking formed plastic away from the mold.
It is significant to recognize that thermosetting plastics are not thermoformed; injection molding method wasn’t utilized on them until 1960.
Blow molding was used first in 1881 and was suitable for cellulose nitrate.
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Blow molding was used first in 1881 and was suitable for cellulose nitrate.
Its tooling cost is relatively high and its production volume is high too.
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Its tooling cost is relatively high and its production volume is high too.
Blow molding is used for hollow articles that usually have small diameter openings compared to the body and examples include containers and bottles.
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Blow molding is used for hollow articles that usually have small diameter openings compared to the body and examples include containers and bottles.
This method is commonly used for high density polyethylene terephthalate and polythene and it forms marks at the point where the mold parts join.
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This method is commonly used for high density polyethylene terephthalate and polythene and it forms marks at the point where the mold parts join.
In blow molding process, a tube is prepared in which hot air is blown into and semi-molten plastic then expands and fills a cavity that the two part form.
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In blow molding process, a tube is prepared in which hot air is blown into and semi-molten plastic then expands and fills a cavity that the two part form.
The two parts are usually mold and plastic. From here,
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The two parts are usually mold and plastic. From here,
it is possible to injection mold the tube in order to allow the formation of a thread used for the lid or any other detail to be created.
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it is possible to injection mold the tube in order to allow the formation of a thread used for the lid or any other detail to be created.
It is also possible to extrude it as a tube which is then pinched at one end before being expanded again to be able to fill the two part metal mold cavity.
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It is also possible to extrude it as a tube which is then pinched at one end before being expanded again to be able to fill the two part metal mold cavity.
The textures can be created on the mold walls. Casting process has been used for decades with traditional materials such as metals.
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The textures can be created on the mold walls. Casting process has been used for decades with traditional materials such as metals.
It has a low tooling cost and production volume too. It is basically a craft process and objects can be added to the liquid when it is solidifying.
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It has a low tooling cost and production volume too. It is basically a craft process and objects can be added to the liquid when it is solidifying.
It is possible to carve the cast form and manipulate the end result of the open casts by using the curing process.
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It is possible to carve the cast form and manipulate the end result of the open casts by using the curing process.
It is commonly used to make plastics from polyurethane and polymethyl methacrylate. The casting process is important in making preformed shapes such as tubes,
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It is commonly used to make plastics from polyurethane and polymethyl methacrylate. The casting process is important in making preformed shapes such as tubes,
radio housings, paperweights, sheets, jewellery, rods and furniture. Under the casting process, the plastic which is in liquid form is poured on an open mold.
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radio housings, paperweights, sheets, jewellery, rods and furniture. Under the casting process, the plastic which is in liquid form is poured on an open mold.
The initial experimentation on the extrusion process took place in 1840s but greatly increased from the late 1930s.
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The initial experimentation on the extrusion process took place in 1840s but greatly increased from the late 1930s. This process can be utilized on any plastic particularly the high density polyvinyl chloride, polythene and polystyrene and all synthetic fibers.
It doesn’t leave any marks has a moderate tooling cost and also a high production volume although it has restrictions on minimum order lengths.
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It doesn’t leave any marks has a moderate tooling cost and also a high production volume although it has restrictions on minimum order lengths. It is used for anything that has a regular cross section and examples include pipes, cable sheathing, tubing, films, sheets and profiles such as window frames or curtain rails.
The process of extrusion involves plastic pellets being fed inside a heat cylinder before being driven forward with the help of a turning screw which is responsible for compacting and melting them and later releasing them through a die located at the end.
This results in to formation of different continuous shapes according to the desired profile. This system is similar to that of a mincing machine but with the exception of addition of heat.
Once the plastic shape has been achieved then air or water is used to cool it. The process of Injection molding is similar to extrusion with the only exception of plastic being injected into a metal mold containing branching used for multi-impression tools.
It was only after 1928 that the injection molding process was successfully carried out with the use of cellulose acetate and became the most popular method of processing thermoplastics from 1946.
From 1960, it was used to process some thermosets. It is commonly used for all plastics and has both high tooling cost and production volume. It is used in high precision technique important in creating complicated shapes such as Airfix kits and medical components.
The products are cheap since they are produced in large volumes and can be used on lego such as machine housings, cutlery and washing-up bowls. This process leaves marks at the point where plastic goes through the mol through a gate that leaves a sprue.
It is then broken off although it leaves behind a circular area that is slightly rough. Sometimes,
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It is then broken off although it leaves behind a circular area that is slightly rough. Sometimes, there are smooth circular marks too left behind too courtesy of the ejector pins that help to remove warm molding away from the mold.
Rotational molding was introduced in the 1940s and has relatively low tooling costs and medium production volume. It is commonly applicable in the case of most medium or commonly low density polythene.
If the finished product needs to be subjected to high temperatures, polypropylene can be used. Although polyamides can be used too, it is rarely used due to the fact that they are expensive.
This process is used in the case of products that have consistent wall thickness and also where its inner surface is inferior to the outside surface which imitates the mold’s surface.
These are normally big simple forms such as traffic bollards and storage tanks. The rotational molding process involves placing a specific volume of material inside a mold which is under rotation at low speed on two axes inside an oven.
The molten plastic reacts by covering and adhering to mold’s inner surface. The mold cools in the rotating process and the final product comes out.

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