Common Core

Functional requirement traits

* Hardness
* Toughness
* Rigidity
* Weight
* Flexibility
* Buoyancy
* Colour
* Texture
* Environment Stability

Economic Requirements traits

Labour costs

Repairs & Servicing

Machinery

Electricity/ bills etc.

Manufacturing Demands

Products are manufactured using different processes and at different scales of production depending on consumer demand. The different processes vary in cost, depending on the number of units produced. These include one-off production, batch, mass, continuous.

Environmental requirements questions

* Will it be outdoors? If so, you may need to consider its ability to resist corrosion. Will it rust?
* Stability-Does the material need to be stable or be able to support

something? Ensuring it doesn't topple will enhance its stability

Permanent Joint

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A permanent joint cannot be un-done without damaging the material

A semi-permanent joint

A joint can be un-done or disassembled without causing damage to the material. Semi-permanent joints are usually done to facilitate disassembly (ie. Whenever you want to be able to take it apart)

Types of Permanent Joints

a) Welding - for joining metals by the use of heat, causing the 2 main pieces of metal to become molten and using a joining material to mix them before they solidify, forming a permanent, strong joint.



b) Brazing - permanently joining metals such as copper and steel under heat using a rod made of an alloy of copper and zinc.



c) Soldering - a similar method to brazing but carried out at lower temperatures.



d) Riveting - using metal pins that are placed through two metal sheets or plates and then hammered flat to join the two elements together.



e) Adhesives - joining materials with glues that are generally invisible. Unlike other methods of joining, adhesives include PVA, Contact Adhesive and Epoxy Resin.



f) Frame joints - for joining wood; common examples include butt joints, halving joints, mortice and tenon joints and dovetail joints. Note that these are normally used in conjunction with suitable wood adhesives.

Semi-permanent joints

a) Screws, nuts, bolts and washers - used to hold two or more pieces of materials together in a semi-permanent method of joining.

b) Snap joints - used for joining moulded plastic components

c) Knock-down fittings - joining materials with screws and plastic or wooden corner blocks; predominantly used in self-assembly products such as 'flat-pack' furniture.

Mechanical Properties

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Refers to how a material reacts when subjected to forces (e.g. strength, hardness, etc.)

Physical properties

refer to the characteristics displayed by the material in relation to non- mechanical influences, e.g. density, electrical and thermal conductivity. It is not just limited to aesthetics.

Density

The density of material is the amount of matter (mass) in an object per unit of space occupied by the matter (volume). Density is a measure of how heavy an object is for a given size, i.e. the mass of material per unit volume.

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Equation = mass/ volume

Electric conductivity

Electrical conductivity is the ability of a material to allow the transfer of electrical energy through it. Good conductive materials allow electricity to flow easily, whilst insulators don’t . Insulating materials (insulators) can resist the flow of electric current. These include woods, ceramics, glass and many plastics, such as nylon, PVC, acrylic and ABS.

Thermal conductivity

Thermal conductivity is the ability of a material to allow the transfer of heat energy through it. Heat transfer occurs at a lower rate across materials of low thermal conductivity than across materials of high thermal conductivity. Conduction rates vary according to a material's reaction to heat and is important that the right materials are chosen for the specific task.

Mechanical Properties

refer to how a material reacts when subjected to forces (e.g. strength, hardness, etc.).

Physical properties

Refers to the characteristics displayed by the material in relation to non- mechanical influences, e.g. density, electrical and thermal conductivity.

Tensile Strength

A material with high tensile strength properties has the ability resist pull forces and would be suitable for production of items such as chains, cables and ropes.

Compressive Strength

Compressive strength is related to a material's ability to withstand push forces that try to crush or shorten it.

Bending strength

Bending strength is the force applied to a material in an attempt to bend 

Shear force

Shear force is the force that subjects materials to a sliding action across their surfaces. This kind of force is present in hinges, rivets, scissors, secateurs for gardening, manual hedge clippers and other tools that involve two or more blades sliding across each other.

Torsional Forces

Torsional force is a force that is applied to a material to try to twist it. It is also known as torque

Elasticity

Elasticity is the ability of a material to flex, bend and be deformed and return to its original shape once the forces are removed. An elastic band is a good example of a material with properties of elasticity. All materials possess elastic properties of various degrees.

Plasticity

Plasticity does not only apply to plastics but it is the ability of an object or material to permanently change shape as a result of forces applied to it, without cracking or breaking. The plasticity of some materials increases when heat is applied

Terms associated with plasticity

• Malleability

• Ductility

Malleability

Malleability is the degree to which materials can be deformed in all directions as a compression force caused by impact such as hammering, pressing, rolling is applied without cracking or breaking the material.

Ductility

Ductility is the ability of a material to be drawn to be longer and thinner, e.g. into wire. The force applied to enable the material to undergo ductile deformation is a tensile force.

Toughness

Toughness is the ability to withstand sudden shocks or blows. A common method used to calculate the toughness of a material is the IZOD impact test.A large pendulum swings to hit a piece of material. The tougher the material, the more capable it is of absorbing the energy of the impact force.

Hardness

Hardness of a material describes the ability to resist indentation. Materials that possess a high degree of hardness have the ability to resist indentation as a result of impact as well as being scratch resistant.

Scratch tests

Minerologists adopt a scale used to rank the scratch resistance ability of materials. The scale is called the Moh's scale and each material will scratch the one coming before it. Diamond has a hardness rating of 10 in Moh's scale.

Indentation tests

There are many different types of indentation test; however, all involve a similar process of forcing a hard object into the surface of a material. The hardness value in these tests are based on the surface area of the indentation or the depth of the indentation.

Three main tests of indenation

• Brinell test (using a hard steel ball)

• Vickers test (using a small pyramid-shaped diamond tool)

• Rockwell test (using either a steel ball or diamond cone)

Durability

The more durable a material is, the more capable it is of withstanding wear and tear and deterioration as a result of weathering. Weathering may cause the material to weaken (mechanically) as well as altering the appearance.

Matierals that are prone to corrusion

Metals are prone to corrosion. This is a chemical breakdown of the surface. Plastics are less prone to decay, which has led to their everyday use in outdoor products. They are, however, difficult to dispose of if they are not recyclable.

Brittleness

If a material is brittle it tends to have poor plasticity properties. Brittleness is the opposite of plasticity. Materials that are brittle tend to break or shatter before they deform. Examples of brittle materials include cast iron and glass.

Hardwood definition and examples

Hardwood comes from deciduous tree's which lose their leaves annually

* Oak
* ash 
* mahogany
* teak
* birch
* beech

Softwood definition and  examples

Softwood comes from conifer, which usually remains evergreen pine

* Pine
* redwood
* cedar
* Cyprus
* fir
* spruce

Forms of wood and forms available

Wood is available in different cross sections and as manufactured boards. It comes in different widths, lengths and thicknesses.

Wood can come in the form of planks, sheets and dowel

Mould

Moulds are available in a range of unusual shapes, such as skirting boards, architrave, ceiling trims

Dowel rod

Dowel rod is circular sections of wood which can be bought in different diameters.

Differences between natural wood and manufactured wood

The main difference between natural timbers and manufactured boards is that they are man-made and manufactured in a factory.

Advantages of manufactured boards

* they are cheaper than natural timber
* they can be cut to any size (you aren't relying on the size of the tree)
* It can be laminated to provide an attractive finish

Plywood creation

Plywood is built up of odd numbers of thin layers (veneers) of hardwood or softwood called laminates, with each one running at 90 degrees to each other. The layers are glued together by an adhesive and pressure applied.

Advantages of plywood

* Plywood is strong because all of the layers of veneers are at right angles to each other.
* It is resistant to warping and cracking which makes it suitable for construction work.
* Plywood is cost effective when compared to solid timber.

Disadvantages of plywood

* Plywood is porous due to the ways the layers have been built up.
* It will splinter badly when cut

Uses of plywood

* Sheds and building cladding
* Roof construction
* Flooring (usually a base layer eg. attics)
* Chairs
* Workbenches (which can be laminated)

Blockboard definition

Blockboard is built up with numerous strips of softwood sandwiched between two sheets of hardwood on the top and bottom and glued together under high pressure.

Advantages of blockboard

* Fairly strong all over sheet
* Cheap
* Resistant to splitting
* It is lighter in weight than MDF and Plywood
* Stability is generally good
* Does not shrink

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Disadvantages of blockboard

* Retains moisture
* Not as strong as the original wood used to construct it
* Needs veneer on the edges

Uses of blockboard

* Bedroom units
* Shelves and common cabinets
* Table tops
* Kitchen worktop

Chipboard definition

Chipboard is made up of wood particles including chips, shavings and sawdust from all different types of commercial timber glued together under heat and pressure.

Advantages of chipboard

* Chipboard is easy to use
* It is relatively cheap
* Depending on use it is a strong material which will withstand pressure
* Chipboard can be aesthetically presented with a variety of wood-like features.

Disadvantages of chipboard

* Chipboard is made up of various small particles, so it is likely to crack and fall apart over time.
* Chipboard will retain moisture it comes in contact with, will swell and become unusable.
* When chipboard is cut it can leave rough edges.
* Its needs veneer to cover it when used as a furniture item.

Uses of chipboard

* Kitchen tops (which are laminated)
* Fire doors
* Furniture 
* Flooring 
* Shelving

Hardboard definition

Hardboard is made from wood fibres obtained from chips and pulped wood waste.

Hardboard advantages and disadvantages

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\- It is cheap.

\- Hardboard has a smooth surface that can be covered easily with paint.

\- Oil tempered hardboard, is resistant to being dented and scratched.

\- Hardboard is adaptable and can be processed in such a way that it is textured, embossed, veneered or backed with plastic

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❌

\- Hardboard is not suitable for outdoors due to its poor resistance to water.

\- It is a weak material

MDF definition and uses

Medium Density Fibreboard is the most common manufactured board used in schools. It is a relatively cheap board of good quality. This board is composed of fine wood dust and resin pressed into a board.

• Kitchens cabinets

• Flooring

• Furniture manufacture

• Panel moulding

• Joinery

Advantages and disadvantages of MDF

✅

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\- MDF is fairly strong and durable.

\- It is easily made in industry.

\- Easily cut, shaped, and drilled.

\- MDF can be manufactured in several different forms.

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❌

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\- MDF can be easily split and damaged

\- Heavy

\- Unless treated with a sealant, MDF will absorb water and swell.

Wood Stains

Wood stain soaks into wood to give it colour and enhance the grain whilst keeping it visible. Wood stains dry a lot quicker than oil based stains, which are more versatile and last longer. Wood stain does not act as a protecting agent. It is cheaper than other wood finishing techniques.

Oils

Oils are used to give a water resistant finish and bring out the natural appearance of wood

They are slower to dry than water based finishes and they do not penetrate the wood as deeply.

Oils are also less likely to produce overlap marks.

Oil generally is applied with a clean cloth and rubbed into the grain.

Polishes

The purpose of a polish is to enhance the beauty of the wood by cleaning the surface finish,raising the shine and giving the wood a deeper, richer look. There are numerous different types of polishes available on the market.

Types of polishes

* Beeswax has been used for centuries to protect wood and help bring out its glossy natural shine.
* Carnauba or silicone wax increases the durability of the wood
* French polish results in a very high gloss surface, with a deep tone and colour. The finish is considered to be one of the most aesthetically pleasing ways to finish wood. Unfortunately, it is also known to be sensitive to damage.
* Cellulose Lacquers can be sprayed straight on to the wood. Unfortunately, they can crack and have a short life due to the brittleness

Venner

A veneer is a thin layer of natural wood which is applied to a surface. It is a natural material and tends to have a richer, more varied appearance. Veneers require more skilled craftsmanship when using laminates and therefore tend to be more expensive.

Laminates

Laminates are a manufactured print of a finish (often wood effect) bonded to a type of surface (e.g. MDF) and topped with an acrylic protective coating. Laminates do not have the same rich and varied finish as veneers but because they are man made they are more resistant to heat and scratches

Paint

Painting timber is one of the most common methods used when applying a finish. It can be used for both aesthetics and protection depending on the type of paint used.

Primer

Primer is a coating put on wood before painting. Priming allows enhanced adhesion of paint to the wood, increases paint resilience and provides protection.

Primer is always required when using oil based paints, and is used before painting for various reasons:

* Wood is absorbent and will soak up the solvent from paint, drying the paint prematurely
* Without a primer, several layers of paint may be necessary to completely obscure the wood grain and ensure even colour.
* Wood can be undercoated before applying a water based paint

Oil paint

Oil paint contains natural or synthetic resins or oils as a base whereas other paints will mainly use water.

Oil Paint dries by oxidation when exposed to air rather than evaporation, so it will take much longer to dry.

Oil based paints are durable and waterproof and are often used on the exteriors of boats.

Polyurethane paint

An oil-based paint containing polyurethane resin makes it tougher and provides a really durable surface to withstand greater abrasion. Polyurethane is used on furniture and toys.

Synthetic resins

Synthetic resins give a much harder and tougher surface finish which is heatproof and waterproof.

It is also capable of withstanding dents and scratches.

It is available in clear, translucent or coloured shades and gives a high gloss, satin or matte finish.

Four steps of applying paints

1\. The wooden surface should be sanded down, smooth and clean. There should be no dust/impediments on the surface.

2\. A primer is then needed in order to give the surface an even surface to bond to, especially if the paint is solvent/oil based.

3\. Once the primer has dried it is important to lightly sand the wood again as it will not be smooth. Not a lot of pressure will be required.

4\. Once the surface is smooth then paint can be applied evenly with a brush. Multiple coats can be applied as desired.

Ferrous metals

Ferrous metals contain Iron and other elements. Almost all ferrous metals, including mild steel, cast iron and tool steel, are magnetic.

Non-ferrous metal

These metals contain no iron. Examples include: Aluminium, Copper, Brass, Zinc

Alloys

Alloys are a mixture of two or more metals or two or more elements, one of which is a metal formed together with other elements to create new metals with improved properties and characteristics.

Stainless steel

A Ferrous alloy used for cookware and cutlery

Process of using paint to finish metals

When metal is to be painted, it is essential to prepare the surface correctly. It must be degreased and cleaned using paraffin, before being washed with hot water and detergent.

To prevent rusting, a primer should be applied, for example a zinc chromate primer is suitable for steel.

Process of using plastic coating to finish metals

Plastic coating is the process of applying a thermoplastic to the surface of metal items to provide long-term corrosion, impact and chemical resistance whilst offering an aesthetically pleasing finish.

The process involves the degreased and clean metal being heated to approximately 180°C before fluidisation (coating process) takes place in a special tank.

The metal object is then submerged quickly into the fluidised powder and left for a few seconds, enabling the powder to stick to the metal in the form of a thin coating. The object is then returned to the oven to allow the coating to fuse and leave a smooth glossy coating.

The process of using electroplating to finish a metal

Electroplating is used to provide metals with a more decorative, appealing or protective surface finish. A common example is silver plating.

The metal object is suspended in an electrolyte (a solution of the appropriate metallic salt) which acts as the conductor. The positive voltage supply is attached to a metal rod or plate made from the material that is be deposited on the object.

Process of using anodising to finish a metal

Anodising is a finishing or protective process associated with Aluminium and is used to thicken the natural oxide film on the surface.

Anodising is electroplating in reverse. The aluminium is immersed in an electrolyte (solution consisting of an acid/water solution).

Processing of using enamelling to finish metals

Enamelling uses powdered glass or minerals which are melted to provide metal with a hard colourful, aesthetically pleasing and protective finish. The surface must be degreased as part of the preparation.

The surface is then brushed with a thin adhesive (polycell paste) which disperses when heat is applied.

Powdered glass or minerals are then sieved to cover the adhesive on the metal object before being transferred to a kiln and heated to approximately 750°C.

When the enamel melts and flows on to the product, it is removed and allowed to cool and harden. Decorative techniques are employed once the enamel hardens.

Process of using Lacquering to finish metals

The addition of a lacquer is to provide a protective barrier against tarnishing and oxidising after polishing.

Lacquer is a clear or coloured varnish that dries by solvent evaporation and often a curing process as well that produces a hard, durable finish, in a range of sheen levels and that can be further polished as required.

For lacquering metals, the surface preparation is similar to other types of finishing. It is recommended to clean the surface with paraffin or white spirit to remove grease. The lacquer is then applied, enabling the natural colour of the metal to be visible.

Thermoplastic definition ,example and uses

a plastic material, or polymer, that can be easily molded or shaped at high temperatures

\- Nylon (fabrics, gear wheels, bearings etc.)

\- PVC (cable insulation, guttering, window frames etc.)

\- Polystyrene (flower pots, model kits, packaging etc.)

\- ABS (kitchen ware, safety helmets, car components etc.)

Advantages and disadvantages of thermoplastics

✅ 

\- They become mouldable after reheating as they do not undergo significant chemical or molecular change. 

\- Thermoplastics tend to be composed of 'long chain monomers'. These types of plastics can be recycled

❌

The weakness of Thermoplastics is that when heat is applied to them they are less useful

Thermosetting plastics and examples

Once 'set' these plastics cannot be reheated to soften, shape and mould. The molecules of these plastics are cross linked in three dimensions and this is why they cannot be reshaped or recycled.

\-epoxy resin ( liquids , pastes)

\- melamine formaldehyde (laminates, granules, powders)

\-polyester resin

Advantages of the thermosetting plastics

The bond between the molecules is very strong These plastics can withstand heat much better than Thermoplastics without losing their rigidity and they are good insulators.

Thermochromic materials

Materials that change colour in response to temperature change. Common examples include baby food utensils and colour changing mugs

Liquid crystals

give a relatively accurate measurement of temperature, which allows them to be widely used in strip thermometers and calculator displays

Leucodyes

Leucodyes are organic chemicals that change colour when heat is applied to them, this makes the molecules move between 2 structures.

The 2 structures are known as colourless 'leuco' or coloured 'non-leuco', both of which reflect light differently.

Examples include t-shirts, coffee cups, receipts.

Photochromic materials

These materials undergo a colour change when they are exposed to light. Since they react to UV light, they are able to be used as UV radiation indicators.

Products such as camera lenses, filters, nail varnish, smart window coatings, clothing, all use this technology to change colour depending on sunlight levels.

Phosphorescent pigments and it's uses

Phosphorescence is a process in which energy absorbed by a substance is released slowly in the form of light. The materials consist of very fine crystals of zinc sulphide, then copper is added as an activator. This allows the crystals to absorb light and slowly emit it over time.



Used in: Escape route signs, Clothing, Shoes, Watches, Toys, Sporting goods

Advantages of phosphorescent

\- Able to absorb, store and emit light

- Some materials can glow in the dark for up to 12 hours 

- They are non-toxic and has no radioactive materials

Reflective Films

On the whole, reflective films recycle light that has not reached the intended direction on its first pass, and directs it back into the system.

Reflective film used in windows in the commercial and domestic market can be made out of one or more layers of polyester.

This film is usually installed to improve energy efficiency by lowering the amount of heat entering the building as a result of sunlight. Reflective films can also be applied on emergency service vehicles such as fire, police, ambulance etc.

Holograms

A hologram is a flat surface that, under proper illumination, appears to contain a 3D image. Holograms are made up of multiple 2D layers, with images placed one behind the other in order to produce the 3D structured effect.



Uses: Product packaging and magazine covers, Credit cards and Driver's licences, Cash: £5/£10/£20 notes



One of the main reasons holograms are used in the examples shown above, is for security reasons. Holograms are very difficult to forge and require expensive, specialised equipment

Three common types of holograms

1) Reflection Holograms

These are illuminated by a white light source on the viewing side of the hologram. The light is reflected from the hologram to show the image.

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2) Transmission

These are viewed by illuminating the rear side of the hologram with a laser. The main advantage of this is that they can produce a sharp, detailed image, whilst also maintain great depth.



3) Embossed

Embossed holograms are commonly found on consumer goods and credit cards. The hologram is embedded on a thin plastic film, backed with reflective aluminium. The aluminium reflects incident light back through the hologram, 'activating it' and making is visible.

Liquid crystal displays (LCD)

LCD's are flat panel display technologies. When all of a pixel's sub-pixels are turned off, it appeas black. When all the sub-pixels are turned on 100%, it appears white. By adjusting the individual levels of red, green, and blue light, millions of colour combinations are possible uses: TVs, computer monitors, mobile devices such as laptops, tablets and smartphones

Polyether ether ketone (PEEK)

A rigid, opaque material with a unique combination of properties. These include exceptional resistance to:

\- Chemicals - Heat - Electricity - Wear



Uses : components for cars, aircraft, industrial pumps, valves and seals, silicon wafer carriers.

Polyphenylsulfone (PPSU)

This is an amorphous plastic, which means it has no clearly defined shape or form. This material combines a high melting point, with quite a low moisture absorption. It also has a high impact strength and chemical resistance. PPSU can be sterilised with superheated steam and is resistant to detergents and disinfectants.

Graphene

The world's first 2D material. Since graphene's isolation in 2004 it has captured the attention of scientists, researchers and industry worldwide.

\- It is ultra-light yet immensely tough.

\- It is 200 times stronger than steel, but it is incredibly flexible.

\- It is the thinnest material possible as well as being transparent.

\- It is a superb conductor and can act as a perfect barrier - not even helium can pass through it.

Potential uses of graphene

Clean drinking water for millions. Graphene membranes could see huge progress in water purification technology in developing countries and provide more efficient desalination plants.



Electronics and energy storage could also be revolutionised by graphene.

\- Flexible, durable, semi-transparent mobile phones. 

\- Wearable technology, clothing that communicates. 

\- Electric sports cars. 

\- Lightweight planes.

 These are the future technologies which are becoming realistic in our present.

Wasting

Wasting is a process that involves removing/taking some of the material away. This occurs when the material is 'wasted' or physically gotten rid of. There are various methods and examples of wasting, both by hand or machine.

Saws

This is a type of hand wasting. Saws are hand-operated with a thin metal blade that has a toothed edge. 

They can be used on wood, metal or plastic. 

It is deemed as wasting as the material is being cut, it is physically torn and some of the material becomes waste. 

e.g. Cross-cut saw, Tenon saw, Coping saw, Dovetail saw, Hacksaw, Rip saw

Files

This is a type of hand wasting. Files are wasting tools are the physically remove the material from the surface. They wear away at the material in order to 'file it down' or remove it.

They can be used on metal or plastic

Files are made from high carbon steel which is heat treated. This makes it tougher than the other materials they used on.

Eg. Flat file, Round File, Half-Round file, Square File

Chisel

This is a type of hand wasting. Chisels are a tool with a purposely shaped edge and a handle.

They are primarily used to cut wood and metal.

They must have a sharp edge for them to do their task effectively and efficiently. 

Eg. Wood chisel, Cold chisel