A presentation on topic Plastics ceramics and glass processing, the all content based on GTU syllabus And ideal for gtu students. The PPT contains videos for clear understanding of concept.

1. GTU

2. Plastic, Ceramic and Glass
Processing
MECH. DIV-A SEM-4

3. Plastics
processing

4. Plastics History

5. General properties: more durable, harder, tough, light.
Typical uses: automobile parts, construction materials.
Plastic types: Thermosets
Examples:
Unsaturated Polyesters: lacquers, varnishes, boat hulls, furniture
Epoxies and Resins: glues, coating of electrical circuits,
composites: fiberglass in helicopter blades, boats, …

6. Plastic types: Elastomers
General properties: these are thermosets, and have rubber-like properties.
Typical uses: medical masks, gloves, rubber-substitutes
Examples:
Polyurethanes: mattress, cushion, insulation, toys
Silicones: surgical gloves, oxygen masks in medical applications
joint seals

7. General properties: low melting point, softer, flexible.
Typical uses: bottles, food wrappers, toys, …
Examples:
Polyethylene: packaging, electrical insulation, milk and water bottles, packaging film
Polypropylene: carpet fibers, automotive bumpers, microwave containers, prosthetics
Polyvinyl chloride (PVC): electrical cables cover, credit cards, car instrument panels
Polystyrene: disposable spoons, forks, Styrofoam™
Acrylics (PMMA: polymethyl methacrylate): paints, fake fur, plexiglass
Polyamide (nylon): textiles and fabrics, gears, bushing and washers, bearings
PET (polyethylene terephthalate): bottles for acidic foods like juices, food trays
PTFE (polytetrafluoroethylene): non-stick coating, Gore-Tex™ (raincoats), dental floss
Plastic types: Thermoplastics

8. Plastics Processing: Extrusion

10. Plastics Processing: Blow molding
heated glass
3-piece mold
(a) The hollow piece of heated glass (parison)
is first created by a blow mold
(see text-book Fig 17.25)
(b) The mold is put together
(c) Plunger and hot air push the
glass up
(d) Hot air blows the glass out towards
the mold surface
(e) Mold comes apart, bottle is removed
heated glass
3-piece mold
(a) The hollow piece of heated glass (parison)
is first created by a blow mold
(see text-book Fig 17.25)
(b) The mold is put together
(c) Plunger and hot air push the
glass up
(d) Hot air blows the glass out towards
the mold surface
(e) Mold comes apart, bottle is removed
- similar to glass blow-molding -

12. Plastics Processing: Thermoforming
Sheet of plastic  Heated (soft)  Molded using a shaped die

13. Vacuum thermoforming

15. Plastics Processing: Compression and Transfer Molding
• used mostly for thermosetting polymers
• mold is heated and closed using pressure
• plastic flows to fills the cavity
• flash must be trimmed by finishing
dishes, handles for cooking pots
skis, housing for high-voltage switches
some rubber parts like shoe soles
and even composites such as fiber-reinforced parts

16. Plastics Processing: Compression and Transfer Molding
compression molding
transfer molding
(more complex shapes)

18. Plastics Processing: Injection Molding
- Probably the most common, most important, most economical process

19. Plastics Processing: Injection Molding
Cycle of operation for injection molding

20. Injection Molding: geometry of the mold
Basic components:
mold pieces (define the geometry of the part), AND
sprue, gates, runners, vents, ejection pins, cooling system

21. Injection Molding: designing injection molds
1. molding directions  number of inserts/cams required, if any
2. parting lines
3. parting planes  by extending the parting line outwards
4. gating design  where to locate the gate(s) ?
5. multiple cavity mold  fix relative positions of the multiple parts
6. runners: flow of plastic into the cavity
7. sprue located:
8. functional parts of the mold
- ejection system: to eject the molded part
- systems to eject the solidified runners
- alignment rods: to keep all mold components aligned

22. Injection Molding: designing injection molds
1. molding directions  number of inserts/cams required, if any
2. parting lines
3. parting planes  by extending the parting line outwards
4. gating design  where to locate the gate(s) ?
5. multiple cavity mold  fix relative positions of the multiple parts
6. runners: flow of plastic into the cavity
7. sprue located:
8. functional parts of the mold
- ejection system: to eject the molded part
- systems to eject the solidified runners
- alignment rods: to keep all mold components aligned
cup
parting line
parting plane
core
cavity
ejection
plate
runner
core
cavity
nozzle knob
cavity
core
(a) (b) (c) (d)
core
cavity
part
core
cavity
ejection
plate
core
cavity
ejection
plate
runner
core
cavity
runner
core
cavity
nozzle knob
cavity
core
nozzle knob
cavity
core
(a) (b) (c) (d)
core
cavity
part
core
cavity
core
cavity
part
gate

23. Runner
Part
Cavity
Nozzle
Part
Cavity
Knob
Stripper
plate
Runner
Part
Cavity
Nozzle
Runner
Part
Cavity
Nozzle
Runner
Part
Cavity
Nozzle
Part
Cavity
Knob
Stripper
plate
Part
Cavity
Knob
Part
Cavity
Knob
Stripper
plate
Runner
Part
Cavity
Nozzle
Runner
Part
Cavity
Nozzle
Designing injection molds: mold in action

25. Ceramics

26. • Properties:
-- Tm for glass is moderate, but large for other ceramics.
-- Small toughness, ductility; large moduli & creep resist.
• Applications:
-- High T, wear resistant, novel uses from charge neutrality.
• Fabrication
-- some glasses can be easily formed
-- other ceramics can not be formed or cast.
Glasses Clay
products
Refractories Abrasives Cements Advanced
ceramics
-optical
-composite
reinforce
-containers/
household
-whiteware
-bricks
-bricks for
high T
(furnaces)
-sandpaper
-cutting
-polishing
-composites
-structural
engine
-rotors
-valves
-bearings
-sensors
Taxonomy of Ceramics

27. Shaping of Ceramics
1- First, the raw materials must be ground or crushed down into fine
particles.
2- Next, the particles must be mixed with additives, which include:
binder- to hold particles together
lubricant- to reduce friction and aid in removing from mold
wetting agent- to improve mixing process (commonly water)
plasticizer- to improve ease of forming mixture
agents- control of foaming and sintering
deflocculent- to create uniform mixture by applying like
charges to all particles, causing them to repel
each other
3- Finally, the material must be shaped, dried, and fired.

28. Crushing is typically done in a ball mill, in either wet or dry conditions.
Wet milling is preferred because it strengthens particle bonds and
limits dust.
For correct sizing, the crushed particles are passed through a
sieve.
• Mixing
Particles are then mixed with one of the additives listed and described on the
previous slide.
Crushing

29. Casting
Slip Casting (Drain Casting)-The crushed particles are first mixed with
water, then are poured into a mold.
Pouring must be done properly to avoid air
pockets.
When some of the water has been absorbed, the
remainder of the mixture is poured out of
the top of the mold.
The top of the part can then be trimmed.
Advantages- inexpensive components
Disadvantages- limited control of dimensions & low production rate
Doctor-Blade Process- Used to produce ceramic sheets thinner than 1.5mm.
Ceramic mixture is forced under a blade to create a film, which is then dried in a
drying chamber (usually attached to the same machine).

30. Forming and Shaping of Glass
Flat Sheet and Plate Glass
Float Method- Molten glass is floated over
a “bath” of molten tin before it is solidified
in a separate chamber.
No additional finishing is necessary.
Drawing Process- Molten glass is
squeezed through two rolls, then
moves on o two smaller rolls.
Rolling Process- Similar to drawing
process, but patterns are commonly
imprinted from the rolls onto the glass,
leaving a rough finish.
Molten Glass

31. Glass Tubing and Rods
Tubing- Molten glass is wrapped around a mandrel and taken out by two rolls.
Air is blown through the mandrel to prevent the tube from collapsing
into itself.
Some machines manufacture 2000 fluorescent light bulbs per minute
using this method.
Rods- Rods are made in exactly the same way,
but without the air blown through
the mandrel.
This allows the glass to collapse and
become solid.

32. Processes used to make discrete glass objects
• Blowing
• Pressing
• Centrifugal casting
• Sagging
Discrete glass products

33. • Blowing process: Blown air
expands a hollow gob of
heated glass against the inner
walls of a mold.
• A parting agent (such as oil
or emulsion) is usually used
to prevent the glass from
sticking to the mold.
Blowing

34. • Applications:
Hollow and thin-
walled glass items
(bottles, vases, and
flasks)
• Surface finish:
Acceptable for
most applications
Blowing

35. • Pressing process: A gob of molten glass is placed
into a mold and pressed by a plunger into a
confined shape.
• Molds may be one piece or split. Solidifying glass
acquires the shape of the mold-plunger cavity.
• Similar to closed-die forging.
Pressing

36. • One-piece molds cannot be used in pressing if the plunger
cannot be retracted.
• One-piece molds cannot be used for thin-walled items
• Split molds can accommodate thin-walled products
Pressing

37. Pressing
• Pressing can produce higher dimensional
accuracy than blowing.
Press and blow process
• After a part is pressed, it is blown to further
expand the glass into the mold.

38. • Centrifugal casting
process: The centrifugal
force pushes the molten
glass against the wall.
• TV picture tubes and
missile nose cones can be
made with centrifugal
casting.
Centrifugal Casting (Spinning)

39. • Sagging process: A sheet of glass is placed over a mold
and heated. The glass sags by its own weight and takes
the shape of the mold.
• Typical applications include dishes, sunglass lenses,
mirrors for telescopes, and lighting panels.
Sagging