The document discusses various aspects of plastics manufacturing processes. It describes how plastics are formed and shaped through molding, cutting, forming, machining and joining. Some key plastics manufacturing processes discussed include injection molding, blow molding, compression molding, transfer molding, reaction injection molding, extrusion, and thermoforming. The properties of plastic parts are influenced by the manufacturing method and processing parameters used. Large, complex shapes can often be formed as a single unit through these plastic fabrication processes.
My presentation on resin transfer molding. Not much description included. For reference i would recommend
" Composite manufacturing by Sanjay Mazumdar".
RTM is a low-pressure molding process, where a mixed resin and catalyst are injected into a closed mold containing a fiber pack or preform . when the resin has cured the mold can be opened and finished component removed.
Blow Molding is defined appropriately and also the process compatible materials are listed. Blow Molding is broadly classified as - extrusion type, injection type, Multilayer type. All three processes are explained appropriately with diagrams and their application is also listed. Since every thing has advantages and disadvantages, so is the case with blow molding. References are also cited correctly. I hope you all find it useful
this is my prsentation of Plastic Process and Processing Parameter in manufacturing process. here discussed moulding process for plastic, plastic injection moulding, machine parts and procedure, material used to making mould and blow moulding process, thermoforming process, vacuum forming process, and application
My presentation on resin transfer molding. Not much description included. For reference i would recommend
" Composite manufacturing by Sanjay Mazumdar".
RTM is a low-pressure molding process, where a mixed resin and catalyst are injected into a closed mold containing a fiber pack or preform . when the resin has cured the mold can be opened and finished component removed.
Blow Molding is defined appropriately and also the process compatible materials are listed. Blow Molding is broadly classified as - extrusion type, injection type, Multilayer type. All three processes are explained appropriately with diagrams and their application is also listed. Since every thing has advantages and disadvantages, so is the case with blow molding. References are also cited correctly. I hope you all find it useful
this is my prsentation of Plastic Process and Processing Parameter in manufacturing process. here discussed moulding process for plastic, plastic injection moulding, machine parts and procedure, material used to making mould and blow moulding process, thermoforming process, vacuum forming process, and application
This topic relates to polymer structure and types of plastic. It also explains the usage and mechanical properties of thermo plastic, thermosetting plastic and the process of making plastic products.
Sustainability of the product is becoming a crucial factor for success in the market. Sustainability theory and methods are quite general. This research constitutes a serious attempt to assess the sustainability of plastic sheet piling, and calculate the product carbon footprint. In the case of plastic sheet piling no significant previous research has been done to address sustainability. The product lifecycle including stages such as raw material production, manufacturing, transportation, installation, and disposal/recycling, and its related supply chain have been analysed in detail to identify those factors that have impact on the product carbon footprint and the three main dimensions of sustainability: environmental, social and economic. The installation stage, which is not normally addressed in this kind of studies, has been assessed by the development of a case study.
How to select a plastic injection molding machine.Naik Devang
Buying a PIMM is not a small investment. Too much machine for the job at hand is wasteful. Too little machine does not get job done. Careful matching of the jobs needs and the attributes of a PIMM is well worth the effort.
Plastics are a wide range of synthetic or semi-synthetic organic compounds that are malleable and so can be molded into solid objects. Plasticity is the general property of all materials which can deform irreversibly without breaking but, in the class of moldable polymers, this occurs to such a degree that their actual name derives from this specific ability.
Ekeeda Provides Online Engineering Subjects Video Lectures and Tutorials of Mumbai University (MU) Courses. Visit us: https://ekeeda.com/streamdetails/University/Mumbai-University
Ekeeda Provides Online Engineering Subjects Video Lectures and Tutorials of Mumbai University (MU) Courses. Visit us: https://ekeeda.com/streamdetails/University/Mumbai-University
Plastic products are made of a mixture of synthetic resin and various additives as raw materials, using injection, extrusion, pressing, pouring, and other methods. While plastic products are being molded, they also obtain the final performance, so plastic molding is a key production process.
The following are 10 common plastic Injection molding methods.
PLASTICS.pdf ALL ABOUT THE JOURNEY OF PLASTICSShriguniAdmane
Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptability, plus a wide range of other properties, such as being lightweight, durable, flexible, and inexpensive to produce, has led to its widespread use. Plastics typically are made through human industrial systems. Most modern plastics are derived from fossil fuel-based chemicals like natural gas or petroleum; however, recent industrial methods use variants made from renewable materials, such as corn or cotton derivatives.[1]
9.2 billion tonnes of plastic are estimated to have been made between 1950 and 2017. More than half this plastic has been produced since 2004. In 2020, 400 million tonnes of plastic were produced.[2] If global trends on plastic demand continue, it is estimated that by 2050 annual global plastic production will reach over 1.1 billion tonnes.
The success and dominance of plastics starting in the early 20th century has caused widespread environmental problems,[3] due to their slow decomposition rate in natural ecosystems. Most plastic produced has not been reused, or is incapable of reuse, either being captured in landfills or persisting in the environment as plastic pollution and microplastics. Plastic pollution can be found in all the world's major water bodies, for example, creating garbage patches in all of the world's oceans and contaminating terrestrial ecosystems. Of all the plastic discarded so far, some 14% has been incinerated and less than 10% has been recycled.[2]
In developed economies, about a third of plastic is used in packaging and roughly the same in buildings in applications such as piping, plumbing or vinyl siding.[4] Other uses include automobiles (up to 20% plastic[4]), furniture, and toys.[4] In the developing world, the applications of plastic may differ; 42% of India's consumption is used in packaging.[4] In the medical field, polymer implants and other medical devices are derived at least partially from plastic. Worldwide, about 50 kg of plastic is produced annually per person, with production doubling every ten years.
The world's first fully synthetic plastic was Bakelite, invented in New York in 1907, by Leo Baekeland,[5] who coined the term "plastics".[6] Dozens of different types of plastics are produced today, such as polyethylene, which is widely used in product packaging, and polyvinyl chloride (PVC), used in construction and pipes because of its strength and durability. Many chemists have contributed to the materials science of plastics, including Nobel laureate Hermann Staudinger, who has been called "the father of polymer chemistry," and Herman Mark, known as "the father of polymer physics"The word plastic derives from the Greek πλαστικός (plastikos) meaning "capable of being shaped or molded," and in turn from πλαστός (plastos) meaning "molded."
Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Automobile Management System Project Report.pdfKamal Acharya
The proposed project is developed to manage the automobile in the automobile dealer company. The main module in this project is login, automobile management, customer management, sales, complaints and reports. The first module is the login. The automobile showroom owner should login to the project for usage. The username and password are verified and if it is correct, next form opens. If the username and password are not correct, it shows the error message.
When a customer search for a automobile, if the automobile is available, they will be taken to a page that shows the details of the automobile including automobile name, automobile ID, quantity, price etc. “Automobile Management System” is useful for maintaining automobiles, customers effectively and hence helps for establishing good relation between customer and automobile organization. It contains various customized modules for effectively maintaining automobiles and stock information accurately and safely.
When the automobile is sold to the customer, stock will be reduced automatically. When a new purchase is made, stock will be increased automatically. While selecting automobiles for sale, the proposed software will automatically check for total number of available stock of that particular item, if the total stock of that particular item is less than 5, software will notify the user to purchase the particular item.
Also when the user tries to sale items which are not in stock, the system will prompt the user that the stock is not enough. Customers of this system can search for a automobile; can purchase a automobile easily by selecting fast. On the other hand the stock of automobiles can be maintained perfectly by the automobile shop manager overcoming the drawbacks of existing system.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
Forklift Classes Overview by Intella PartsIntella Parts
Discover the different forklift classes and their specific applications. Learn how to choose the right forklift for your needs to ensure safety, efficiency, and compliance in your operations.
For more technical information, visit our website https://intellaparts.com
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
2. INTRODUCTION
2
The processing of plastics involves operations
similar to those used to form and shape metals.
Plastics can be molded,cut,formed,machined &
joined.
Plastics are usually shipped to manufacturing
plants as pallets or powders & are melted just
before the shaping process.
Plastics are available as sheets,plate,rod,and
tubing,which may be formed into a variety of
products.
3. 3
The properties of plastic parts are influenced greatly
by the method of maufacturing and by the processing
parameters . Materials in these classes can often
provide integral & variable color.
The processes used to manufacture the shape can
frequently produce the desired finish and precision.
The joining and fastening operations also tend to be
different from those used with metals.
Large , complex shapes can often be formed as a
single unit.
4. PLASTICS
4
- Plastic is a material consisting of any of a wide range
of synthetic or semi-synthetic organics that are
malleable and can be molded into solid objects of
diverse shapes.Plastics are typically organic polymers
of high molecular mass, but they often contain other
substances.
- They are usually synthetic, most commonly derived
from petrochemicals, but many are partially natural.
- PLASTICITY:-
Plasticity is the general property of all
materials that are able to irreversibly deform without
breaking
9. PROPERTIES OF PLASTICS
9
Following are the general properties of plastics.
1. STRENGTH:-
The plastics are sufficiently strong and can be used for
load bearing structural members. The strength of plastics can further be
increased by reinforcing them with various fibrous materials.
2. WEATHER RESISTANCE:-
The plastics, prepared from phenolic resins,
are only good in resisting weather effects. Certain plastics are seriously
affected by ultraviolet light.
3. FIRE RESISTANCE:-
Plastics, being organic in nature, are
combustible. But the resistance to fire temperatue depends upon the
plastic structure.
Cellulose acetale plastics burn slowly.
Polyvinyl chloride (PVC) plastics are non-inflammable.
10. 10
4. DURABILITY:-
Plastics generally possess sufficient
durability, provided they offer sufficient surface
hardness. Thermoplastic varieties are found to be
attacked by termites and rodents.
5. DIMENSIONAL STABILITY:-
Plastics easily maintain its
shape and do not go under plastic deformations.
6. CHEMICAL RESISTANCE:-
Plastics offer great resistance
to moisture, chemicals and solvents. Many plastics are
found to possess excellent corrosion resistance.
Plastics are used to convey chemicals.
7. THERMAL RESISTANCE:-
The plastics have low thermal
conductivity and therefore foamed or expanded
varieties of plastics are used as thermal insulators.
11. 11
9. MOISTURE RESISTANCE:-
This property depends upon variety of
plastics used, for example, cellulose plastics are considerably affected
by the presence of moisture, whereas polyvinyl chloride plastics offer
high resistance to moisture.
10. DUCTILITY:-
Plastics, generally, have low ductility and hence
plastic structural members may fail without prior warning.
11. MISCELLANEOUS PROPERTIES:-
Plastics are available in variety of colors,
both opaque and transparent.
Plastics possess excellent insulating
property, so used as electric insulators.
Plastics are clean, light and shining, so they
need not be given any finish such as
12. RESIN
12
In polymer chemistry and material science, resin is a
"solid or highly viscous substance," which are typically
convertible into polymers. Such viscous substances
can be plant-derived or synthetic in origin. They are
often mixtures of organic compounds.
14. THERMOPLASTIC RESIN
14
Thermoplastic resin is a polymer compound that becomes
soft or fluid when heated and then returns to its original
solid state when cooled. This compound is used in molding
processes like injection molding, which requires the raw
material to be in a liquid or plastic state to fill the mold
completely. When cooled, the resin or polymer solidifies to
form the finished product, which is then ejected or dropped
out of the mold. The resin is used to manufacture many
consumer products.
15. THERMOSETTING RESIN
15
Thermosetting resins are rigid
polymeric materials that are
resistant to higher temperatures
than ordinary thermoplastics.
These materials are normally
made up of lines of polymers,
which are highly cross-linked.
The heavily cross-linked structure
produced by chemical bonds in
thermoset materials is directly
responsible for the high
mechanical and physical strength
compared with thermoplastics or
17. ELASTOMERS
17
An elastomer is a polymer with viscoelasticity (having
both viscosity and elasticity) and very weak inter-
molecular forces, generally having low Young's
modulus and high failurestrain compared with other
materials.
Elastomers are amorphous polymers existing above
their glass transition temperature, so that considerable
segmental motion is possible.
Elastomer is a big fancy word, and all it means is "rubber".
Some polymers which are elastomersinclude polyisoprene
or natural rubber, polybutadiene, polyisobutylene, and
polyurethanes.
18. (A) is an unstressed polymer; (B) is the same polymer
under stress. When the stress is removed, it will return to
the A configuration. (The dots represent cross-links)
18
20. FABRICATIONS OF PLASTICS
20
Plastic fabrication is the
design, manufacture, or
assembly of plastic
products through one of a
number of methods.
Some manufacturers
prefer plastic fabrication
over working with other
materials (such as metal
or glass) due to the
process’s advantages in
certain applications.
Plastic's malleability and
cost-effectiveness can
make it a versatile and
durable material for a
21. 21
Casting , Blow Molding , Compression Molding , Transfer
Molding , Cold Molding , Injection Molding, Reaction
Injection Molding , Extrusion, Thermoforming, Rotational
Molding and Foam Molding are all processes that are used
to shape polymers.
Each has its distinct set of advantages and limitatioms that
relate to part design , compatible materials,and producion
cost.
23. 1. CASTING
23
Casting is the simplest of the shape forming processes
because no fillers are used and no pressure is required.
While not all plastics can be cast, there are a number of
castable thermoplastics, including acrylics, nylons,
urethanes, and PVC plastisols.
Since cast plastics contain no fillers, they have a distinctly
lustrous appearance, and a wide range of transparent and
translucent colors are available.
Some thermosets (such as phenolics, polyesters, epoxies,
silicones, and urethanes) can also be cast, as well as any
resin that will polymerize at low temperatures and
atmospheric pressure.
24. 24
A steel pattern is dipped into molten lead,withdrawn, and
allowed to cool. A thin lead sheath is produced when the
pattern is removed, and this becomes the mold for the
plastic resin .Curing occurs ,either at room temperature or
by heating for long times at temperatures in the range of
65° to 95° C. After curing, the product is removed, and the
lead sheath can be reused
fig:- steps in the casting of thermoset plastic parts
using a lead sell mold.
25. 2. BLOW MOLDING
25
Blow molding is the process of inflating a hot, hollow,
thermoplastic preform or parison( a tube-like piece of plastic
with a hole in one end through which compressed air can pass.)
inside a closed mold so its shape conforms to that of
the mold cavity. A wide variety of hollow parts, including plastic
bottles, can be produced from many different plastics using this
process.
In general, there are three main types of blow molding:
extrusion blow molding, injection blow molding, and injection
stretch blow molding.
A variety of blow molding processes have been developed, the
most common being used to convert thermoplastic
polyethylene,polyvinyl chloride(PVC), polypropylene, and
26. 26
A solid bottom ,hollow –tube preform, known as parison, is
made from heated plastic by either extrusion or injection
molding. The heated preform is then positioned between the
halves of a split mold,the mold closes,and the preform is
expanded against the mold by air or gas pressure. The mold
is then cooled, the halves separated and the product is
removed.
28. 3. COMPRESSION MOLDING OR HOT-
COMPRESSION MOLDING
28
Compression molding is a forming process in which a
plastic material is placed directly into a heated metal mold,
then is softened by the heat, and forced to conform to the
shape of the mold as the mold closes.
The process employs thermosetting resins in a partially
cured stage, either in the form of granules, putty-like
masses, or preforms.
Compression molding is a high-volume, high-pressure
method suitable for molding complex, high-
strength fiberglass reinforcements.
However, compression molding often provides poor
29. 29
The compression molding starts, with an allotted amount of
plastic or gelatin placed over or inserted into a mold. Afterward
the material is heated to a pliable state in and by the mold.
Shortly there after the hydraulic press compresses the pliable
plastic against the mold, resulting in a perfectly molded piece,
retaining the shape of the inside surface of the mold. After the
hydraulic press releases, an ejector pin in the bottom of the
mold quickly ejects the finished piece out of the mold and then
the process is finished
31. 4. TRANSFER MOLDING
31
Transfer molding is a process where the amount of material
is measured and inserted before the molding process takes
place. The material is then preheated and loaded into a pot
and a plunger is then used to force the material from the pot
through the runner system into themold cavities.
Transfer molding is different from compression molding in
that the mold is enclosed [Hayward] rather than open to the
fill plunger resulting in higher dimensional tolerances and less
environmental impact.
The material most commonly used for transfer molding is a
thermoset polymer.
Defects known as voids and dry resin (in the case of resin
32. 32
The fill material ( preheated solid or a liquid) is loaded into a
chamber known as the pot. A ram or plunger forces material
from the pot into the heated mold cavity. If feed-stock is initially
solid, the forcing pressure and mold temperature melt it.
Standard mold features such as sprue channels, a flow gate
and ejector pins may be used. The heated mold ensures that
the flow remains liquid for complete filling. Once filled the mold
can be cooled at a controlled rate for optimal thermoset curing.
34. 5. COLD MOLDING
34
In cold molding, the uncured thermosetting materials is pressed
to shape while cold and Is then removed from the mold and
cured in a separate oven.
While the process is faster and more economical, the resulting
products generally lack good surface finish and dimensional
precision.
In general, advantages of these materials include high arc
resistance, heat resistance, good dielectric properties,
comparatively low cost, rapid molding cycles, high production
with single-cavity molds (thus low tool cost), and no need for
heating of molds.
35. 35
On the other hand, they are relatively heavy, cannot be
produced to highly accurate dimensions, are limited in
color, and can be produced only with a relatively dull
finish.
36. 6. INJECTION MOLDING
36
Injection moulding can be performed with a host of materials,
including metals, (for which the process is
called diecasting), glasses,elastomers, confections, and most
commonly thermoplastic and thermosetting polymers. Material
for the part is fed into a heated barrel, mixed, and forced into a
mould cavity, where it cools and hardens to the configuration
of the cavity.
Granules of raw materials are fed by gravity from a hopper into
a cavity that lies ahead of a moving plunger. As the plunger
advances, the material is forced through a preheating
chamber and on through a topedo section, where it is mixed,
melted, and superheated.
37. 37
The superheated material is then driven through a nozzle that
seats against a mold.
Other types of injection units control the flow of material and
generate the injection pressure with screws that have both
rotational and axial movements, or combinations of screws and
plungers.
40. 7. REACTION INJECTION MOLDING
40
Reaction injection molding (RIM) is similar to injection
moldingexcept thermosetting polymers are used, which
requires a curingreaction to occur within the mold. Common
items made via RIM include automotive bumpers, air spoilers,
and fenders.
In this process two or more liquid reactants are metered into
a unit where they are intimately mixed by the impingement of
liquid streams that have been pressurized to a value between
13 and 20 MPa. The combined materials flows through a
pressure –reducing chamber and exits the mix-head directly
into a mold.
An exothermic chemical reaction takes place between the two
components, resulting in thermoset polymerisation.
44. 8. EXTRUSION
44
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
, weatherstripping, fencing,deck railings,window
frames, plastic films and sheeting, thermoplastic coatings,
and wire insulation.
This process starts by feeding plastic material (pellets,
granules, flakes or powders) from a hopper into the barrel of
the extruder. The material is gradually melted by the
mechanical energy generated by turning screws and by
heaters arranged along the barrel. The molten polymer is
47. 9. THERMOFORMING
47
Thermoforming is a manufacturing process where a plastic
sheet is heated to a pliable forming temperature, formed to a
specific shape in a mold, and trimmed to create a usable
product.
Thin-gauge thermoforming is primarily the manufacture of
disposable cups, containers, lids, trays, blisters, clamshells,
and other products for the food, medical, and
general retail industries. Thick-gauge thermoforming includes
parts as diverse as vehicle door and dash panels, refrigerator
liners, utility vehicle beds, and plastic pallets.
48. 48
The heated sheet indexes into a form station where a mating
mold and pressure-box close on the sheet, with vacuum then
applied to remove trapped air and to pull the material into or
onto the mold along with pressurized air to form the plastic to
the detailed shape of the mold.
After a short form cycle, a burst of reverse air pressure is
actuated from the vacuum side of the mold as the form tooling
opens, commonly referred to as air-eject, to break the vacuum
and assist the formed parts off of, or out of, the mold.
Its simplified version is VACUUM FORMING.
50. 10. ROTATIONAL MOLDING
50
Rotational Molding, also called rotomolding or rotocast, is
a thermoplastic process for producing hollow parts by
placing powder or liquid resin into a hollow mold and then
rotating that tool bi-axially in an oven until the resin melts
and coats the inside of the mold cavity.
Rotational Molding involves a heated hollow mold which
is filled with a charge or shot weight of material. It is then
slowly rotated (usually around two perpendicular axes)
causing the softened material to disperse and stick to the
walls of the mold.
51. 51
In order to maintain even thickness throughout the part,
the mold continues to rotate at all times during the heating
phase and to avoid sagging or deformation also during the
cooling phase.
Process is shown below by simple animation :-
54. 11. FOAM MOLDING
54
In foam molding, a foaming agent is mixed with the plastic
resin and releases gas or volatilizes when the material is
heated during molding.
The materials expand to 2 to 50 times their original
size,resulting in products with densities ranging from 32 to
640 g/L.
Open-cell foams have interconnected pores that permit the
permeability of gas or liquid.
Closed-cell foams have the property of being gas-or liquid-
tight.
Prefoamed polystyrene beads can be expanded and fused to
56. OTHER PLASTIC- FORMING
PROCESSES
56
CALENDERING:- A mass of dough like thermoplastic is
forced between and over two or more counter-
rotating rolls to produce thin sheets or films of
polymer, which are then cooled to induce hardening.
DRAWING:- Conventional drawing can be used to
produce fibres.
57. 57
ROLLING:- Rolling can be performed to change the shape
of thermoplastic extrusions.
SPINNING:- Filaments, fibres, and yarns can be produced
by spinning, a modified form of extrusion in which
molten thermoplastic polymer is forced through a die
containing many small holes called a spinneret.