Design & manufacture
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Transcript of Design & manufacture
LECTURE-3
DESIGN & MANUFACTURE
Working with manufacturersIntegrating design and manufactureSelecting Materials
Common MaterialsCERAMICS an inorganic, nonmetallic solid
prepared by the action of heat and subsequent cooling.
Traditional ceramic applications include tiles, whiteware such as toilets and sinks and pottery.
Technical ceramic applications that take advantage of the high thermal conductivity of ceramic include heat sinks for electronic circuitry.
StonewareHigh fired clay is usually grey to brown in
color due to the presence of iron and other impurities in the clay.
It differ from earthenware in that it has very little moisture absorbency once fired.
Stoneware is commonly used or tableware when glazed
EarthenwareLow temperature fired clay , usually red or
orange color.Used to make pots industrially as well as
large sculpture and architectural formsFired at normally low temperature leaving
the body porous if not glazed
Porcelain The wondrous white translucent ceramic is fired at a
high temperature to fuse the glaze and clay body together to produce a highly refined material.
Made by firing a pure clay and then glazing it with different colors
sonorous, nonporous It is mainly used for utilitarian wares and artistic objects. China clay or Kaolin
COMPOSITESEngineered materials made from two or more
components.However, within the composite you can easily tell the
different materials apart as they do not dissolve or blend into each other
Natural composites exist in both animals and plants. Wood is a composite – it is made from long cellulose fibers (a polymer) held together by a much weaker substance called lignin
The bone in your body is also a composite. It is made from a hard but brittle material called hydroxyapatite (which is mainly calcium phosphate) and a soft and flexible material called collage(which is a protein).
Making compositesMost composites are made of just two
materials. One is the matrix or binder. It surrounds and binds together fibers or fragments of the other material, which is called the reinforcement.
FIBREGLASSThe first modern composite material was
fiberglass. It is still widely used today for boat hulls,sports equipment, building panels and many car bodies. The matrix is a plastic and the reinforcement is glass that has been made into fine threads and often woven into a sort of cloth.
On its own the glass is very strong but brittle and it will break if bent sharply. The plastic matrix holds the glass fibers together and also protects them from damage by sharing out the forces acting on them.
CARBONFIBRESome advanced composites are now made
using carbon fibres instead of glass. These materials are lighter and stronger than fibreglass but more expensive to produce. They are used in aircraft structures and expensive sports equipment such as golf clubs.
Consists of woven carbon-fiber yarn, combine with resin to produce a mouldable sheet material
Material has high strength to weight ratio.
HoneycombThese composites consist of a core
hexagonal structure name after its visual resemblance to a bee’s honeycomb, skinned either side by a sheet.
Produce mostly as a sheet material in aluminum and glassfibre
Advantage of stiffness combined with low weight and are often used for architectural and light weight structures.
Why use compositesThe biggest advantage of modern composite
materials is that they are light as well as strong. By choosing an appropriate combination of matrix and reinforcement material, a new material can be made that exactly meets the requirements of a particular application. Composites also provide design flexibility because many of them can be moulded into complex shapes. The downside is often the cost. Although the resulting product is more efficient, the raw materials are often expensive
LAMINATESThis group of material is commonly defined
by its layering of materials together using adhesives.
Plywood is common example of a laminate made up of layers of the same material.
The process of lamination enables such materials to be surfaced with colored polymer sheets such as formica or metal finishes.
Withstand high temperatures up to 400 degree & thermal stresses, owing to its low thermal expansion coefficient
High resistance to chemical agent Hard glass, less dense from normal glass Uses:
Neon tubesIndustrial pipes & columnsTelescope mirror
Resistance to sudden fall in temperature is low.
GLASS, Borosilicate (PYREX)
Glass, Coated1. Metal deposition
Surface treatments-( Aesthetic or technical reasons) Deposits are applied in a vacuum or by direct
coating Self-cleaning glass
Self-cleaning glass is a specific type of glass with a surface which keeps itself free of dirt and grime.
Self-heating glass One way mirrors
Laminated glass
Glass toughened or Tempered Tempered glass, or toughened glass, is
glass that has been heat-treated to make it stronger, more resistant to heat and break in a way to prevent injury.
Cut the glass into the desired shape first. This has to be done before the glass is tempered, as the tempering process will weaken the glass if it is cut or etched afterward and may increase the likelihood of breakage.
Inspect the glass for imperfections. Cracks or bubbles may cause the glass to break during tempering; if any are found, the glass cannot be tempered.
Sand the cut edges smooth. This removes any burrs created during cutting or etching.
Wash the glass. This removes any tiny grains of glass deposited during sanding, as well as any dirt that may interfere with the tempering process.
Heat the glass in a tempering oven. Glass may be fed in batches or continuously. The oven reaches temperatures of over 600 degrees Celsius (1,112 degrees Fahrenheit), with the industry standard being 620 degrees Celsius (1,148 degrees Fahrenheit).
Quench the glass to cool it. The heated glass is subjected to seconds of high-pressure blasts of air at various angles. The rapid cooling causes the outer surfaces of the glass to cool and contract faster than the center, giving the tempered glass its strength.
Plastics/ ThermoplasticsAcrylonitrile butadiene styrene:Highest impact resistanceHigh mechanical strengthBetter resistance to heat and chemical agentsLight weightApplications:
Cars dashboards,radiator grillsElectronic industry ( telephone and tv set cases)Vacuum cleaner bodiesToys and office furniture
Poor resistance to UV
AcrylicTransparent material also known as
polymethylmethacrylate (PMMA)Used as alternative to glassUse in lighting, aircraft windows and
spectacle lenses, where its rigidity and hardness are necessary. It is recyclable and non toxic
Polypropylene (PP)Semi-crystalline thermoplasticGood chemical resistanceExcellent electrical insulationHigh fatigue resistance ( hinges, repeated
bending)Low coefficient of frictionGood impact resistanceVery sensitive to UVHigh shrinkage when mouldedAverage mechanical strength
POLYSTYRENE Amorphous thermoplastic Transparent and good appearance of crystal form
( smooth, shiny surface) Easy to use with adhesives or to weld Easy to mark, decorate, print on, easy to color Sensitive to impact and scratching Very sensitive to chemical agents
Pvc (Polyvinylchloride)Amorphous thermoplastic materialFlexible or rigidChemical resistanceGood electrical insulationSelf-extinguishing so still useful in buldingsSensitive to uvLimited chemical resistance when
transparentPoor impact resistance at low temperature