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