Product Design (technical Principles)

Die Casting

1.the process of forcing molten metal into a metallic mold under hydraulic pressure to give it a particular shape or form.

2.complex/expensive to make dies to best for mass production

3.High quality finish

4.metals with low melting points used so the molten metal doesn't melt the die in the process

Gravity Die-casting

1.Molten metal is poured into dies through runners, this process uses the force of gravity to ensure the molten reaches all parts of the mould.

Pewter casting

1.A mould is made and pewter that has a low melting point is heated and poured into the mould

2.used in schools because pewter has a low melting point/uses simple equipment/easy process for children to do

3.used for one off production

investment casting

1.a shape in wax is created, and then covered with plaster or ceramic material (investment). When investment has hardened, the wax is melted out, then molten metal is poured in. Also known as (lost wax casting)

2.metals used are stainless steel/aluminium/brass/steel

3.disadvantages: expensive as ceramic mould has to be destroyed to get product out/time consuming as takes a week to make mould

4.advantages: metals with high melting point can be used as metal+die won't fuse together during process/high quality finish

Polyurethane varnish

1.an exceptionally hard, abrasion-resistant, and chemical/heat/water resistant

2. Matt/satin/gloss finish

3.used on boats/wooden flooring

4.disadvantages: not UV resistant so will yellow/can make woods look fake/water based better for the environment/long drying time/health risks

Wax finishes

1.advantages: easy to apply/nourishes the wood/some food safe and non toxic

2. Disadvantages: limited protection against moisture/heat/scratches/has to be applied regularly

Danish oil

1.A wood finish which maintains the natural appearance of the wood as well as enhancing the grain

2.advantages:water resistant/durable/satin finish/food safe/non toxic

Pressure treated timber (tantalising)

1.timber is treated using an anti microbial copper based preservative before being sold

2.advantages: weather protection/insect and fungus resistant

3.usually used for fence posts/playground equipment/construction materials

Testing-tensile strength (destructive)

1.The ability to resist pulling/twisting forces

2.This can be tested in a workshop by clamping material samples of the same length and thickness into a vice and applying a load such as weights to the unclamped end.Then measure the deflection of the material

3.in industry,material is clamped in machine and slowly Stretched until material snaps the results are plotted On a stress/strain graph

Testing-Hardness (destructive)

1.the ability to resist being cut and scored

2.vickers pyramid test:diamond square based pyramid to indent the surface
3.Brinell test:uses steel ball to indent the surface
4.Rockwell test:uses diamond indenter to break the surface, additional load is applied then released

5.in all of the tests the depth if the indention or diameter is measured

Testing-malleability/ductility (destructive)

1. The ability to resist deformation by compression without cracking

2.Secure the test piece into the vice. Try to bend the test piece 90 degrees. Cracks or surface damage on the outside of the bend indicates a lack of ductility. Cracks or surface damage on the inside of the bend indicates a lack of malleability.

Testing-corrosion (destructive)

1.all test pieces should be the same size. Materials can simply be placed outside in an area exposed to weather effects and left for a certain length of time. Materials can then be visually inspected for surface corrosion.

Testing-X-rays (non-destructive)

1.X-ray beams are passed through a material to project an image on a screen
2.can measure wood rings and see if there are any splits in the wood

Testing-ultrasonic tests (non-destructive)

1.detects internal defects using sound waves

2.sound waves pulsed into material and the intensity of the reflected sound waves is recorded

3.advantages:highly accurate/quick/portable

Vacuum Forming

-sheet of thermoplastic is heated and pressed onto the mould by atmospheric pressure
-the plastic then takes on the shape of the mould and cools to set into position before mould is removed

-usually used for yoghurt pots and baths

Thermoforming (polymers)

-Like vacuum forming,where a sheet of polymer and creating a different shape using a mould
-difference is it uses a male and female mould
-male mould is lowered into the heated sheet and presses onto the female mould and then a vacuum helps to pull the polymer into the mould

Line bending (polymers)

-used to create a permanent fold/bend in a plastic product e.g photo frames/menus
-Avoid overheating which causes blistering.
-The use of formers or jigs will improve accuracy in bending to certain angles or shapes

1.turn strip heater on
2.place plastic over strip heater where you want the bend and leave for a few minutes
3.time to become flexible depends on thickness/type of polymer
4.test flexibility of polymer and when ready bend the acrylic either using a jig or without
5.leave polymer to cool before moving it

Extrusion (polymers)

-Used to create a continuous flow of plastic that is pushed through die to make specific shape

1.plastic granules put in a hopper and fed through a heated Archimedes screw this makes sure all the plastic is heated thoroughly.
2.passes through the die and kept at a continuous tension through a water tank to cool down

-usually used to make plastic bags and cables

Tungsten carbide (composite)

-A composite which is resistant to high temperatures, hard and tough. This makes is suitable for drill bits

Carbon Fibre Reinforced Plastic (CFRP) (composite)

-A composite which is lightweight and used for bicycle frames. It is tough, hard and has a good compressive strength. It is also corrosive resistant

Aluminium composite board (composite)

-Polymer core with an aluminium sheet of aluminium
-A composite which is lightweight and rigid. It is good at absorbing vibrations and sound. It is mostly used for signs

Phosphorescent pigment (smart material)

Absorbs light energy during the day and 're-emits' the light energy when it is dark

Piezoelectric material (smart material)

A smart material which when deformed gives off a small electrical discharge. When an electric current is passed through it, it increases in size (up to a 4% change in volume). They are widely used as sensors in different environments and used in the airbag sensor on a car.

Polymorph

-Thermoplastic material that becomes malleable at low temperatures
-When heated to 62 degrees easy to mould and remoulded many times
-Once cooled extremely tough and durable
-non toxic/biodegradable

Usually used for ergonomic products like handles for knives and forks as safety feature

Sealants

-blocks the passage of air and fluids through metal joints
-sealants used on metals usually polymer based
-help prevent decay/weathering/corrosion

High speed steel (ferrous alloys)

-resistant to friction
-hard
-tough
-used for tool blades/drill bits

High pressure Die-Casting

1.Casting process which involves forces molten metal into the mould under pressure using a hydraulic plunger

2.ejector pins release the casting from the die

3.used for more intricate shaped products to the molten metal goes into all the crevices

Sand casting

1.A process of pressing moist sand around a pattern to make a mold. The pattern is removed, leaving a cavity in the sand. The cavity is the mold that will be filled with liquid metal. The result will be a casting that is identical in shape to the original pattern.

2.one off and batch production

3.used for metals with high melting points as metal+die won't fuse together

4.slow and labour intensive/moulds are single use

Acrylic varnish

1.A wood finish which is clear and allows the wood's natural grain to show, it provides a hard, tough and heat/waterproof finish

2.non toxic/odourless/doesn't yellow with age

Water-based paints

1.A wood finish which provides protection and colour , as well as improving toughness and hardness

2.advantages:low odour/low volatile organic compounds (VOCs)/quick drying/easy to use and clean up

3.certified "toy safe"for children's toys as children tend to put toys in their mouth

Wood Stains

1.Puts a colour on the wood whilst keeping the natural grain of the wood exposed

2.advantages: aesthetic finish/available in range of Colours

3.disadvantages: no protection from decay or degradation

Wood oils

1.used to replace natural oils lost over time and nourish the wood

2.disadvantages:little protection form scratches /heat/liquid

3.advantages:non toxic/food safe/easier to apply than wax/provides more protection

Teak oil

1.A wood finish that is used for outdoor wood products as it added a weather resistance as well as preventing fungus and insect attack provides UV protection

2.used for boats and outdoor furniture

Pressure treated timber (tantalising) process

1.timber loaded in treatment vessel and vacuum turned on to get rid of any air in the vessel
2.vessel flooded with tantalising preservative
3.hydraulic pressure added forcing preservatives into timber
4.vacuum extracts excess preservative
5.low pressure inside timber forces any preservative left on the surface into the timber
6.timber left to dry

Testing-toughness (destructive)

1.the ability to absorb energy and deform plastically

2.The Izod impact test is used to test the toughness of a material. A notched test piece is held vertically in the vice of a test machine. A pendulum is released from a set position and swings to strike a test piece. The energy absorbed by the test piece is calculated from the height the pendulum swings to after it hits the test piece. The material that absorbs the most impact is the toughest. This is shown the distance the pendulum travels after breaking the material. The further it swings, the less energy the sample absorbs and the more brittle the material

3.charpy impact test is used and the material is held horizontally in place using clamps.a hammer is the used to test the toughness of the material

Testing-Electrical conductivity (destructive)

1.collect material samples of the same dimensions and, on the top surface, mark a set distance between the ends of the material sample. The distance is the spacing for each probe of the multimeter. Place the probes on the distance marks and measure the resistance on the multimeter. The higher the resistance, the lower the conductivity

Testing-Thermal conductivity (destructive)

1.Collect metal samples of the same dimensions. Measure a set distance from one end of the material on which to place a thermometer. A bunsen burner is lit to reach a set point at the other end of the material sample. The shortest time it takes to reach the set temp, the higher the thermal conductivity

2.guarded hot plate method is used to test thermal conductivity in woods.test material placed in between two temp controlled plates one is kept hit and the other cold.test measures the time taken for the material to reach a constant temp

Calendering (polymers)

-process using series of rollers to produce thin polymer sheets/film

1.polymer pellets heated
2.polymer pellets extruded through series of rollers
3.flattens and stretches polymer
4.final rollers cool the sheet and is either rolled or cut to length

Laminating (polymers)

-the process of bonding two or more layers of material together to form a thicker and stronger product

1.fibre strands e.g Kevlar or carbon fibre used to make the sheets that will be bonded together
2.mould made from timber or metal
3.release agent added to the mould
4.polyester gel coat added and cured
5.fibre strands are added and mixed with catalyst to bond them together
6.the rolled to remove air bubbles and then allowed to set

Injection moulding

-process in which hot liquid plastic is injected by force into a mould usually used to make complex shapes

1.thermoplastic granules fed into hopper
2.hopper feeds into archimedes screw that is heated to melt the granules
3.when the softened plastic reaches the end of the screw a hydraulic piston forces the plastic into a mould

Blow moulding

-This process is one of the most common moulding processes. It is used to manufacture things such as drinks bottles and shampoo bottles and other hollow plastic products.

1.polymer granules are heated and extruded to create tube called parison
2.parison is fed into mould and pinched at bottom and then filled with compressed air then mould closed tightly
3.this inflates the parson around the shape of the mould
4.plastic cools and takes on shape of the mould

Rotational moulding

-used to create hollow plastic forms and products seamless

1.polymer granules weighed depended on desired wall thickness and out into mould
2.mould placed on a rig in oven and heated
3.As it's heated acts roasted slowly in 2 axes allowing polymer to coat the inside of the mould
4.one desired thickness is reached the mould is cooled

Compression moulding

-moulding using heat and a two-part mould to squash the polymer into form using a hydraulic press

1.two separate moulds are used,male and female,and pushed together to form the product
2.the moulds are heated and a form of plastic is placed between the moulds
3.a hydraulic press causes the mould to push together heating the plastic form to create the product
4. Then left to cool and the part is removed by pressing an ejector pin

Glass reinforced plastic (GRP) (composite)

-Polyester or epoxy resin is combined with fibres made of thin glass
Advantages:Lightweight/low maintenance/an endless range of colours/durable/UV resistant/waterproof/cheaper than carbon fibre

-disadvantages:Difficult to repair, time-consuming to manufacture. Produces a fine dust

Fibre cement (composite)

-Made from cement and cellulose and synthetic fibres

-Advantages:durable/lightweight/resistant to rust,weathering,chemical and insects attack/good thermal and noise insulator

Concrete (composite)

-Made from cement,water,sand and gravel

-Advantages:heavy/durable/has high compressive strength/good thermal insulator which can decrease buildings heating cost

Steel reinforced concrete (composite)

-Concrete strengthened by steel rods or mesh. This improves tensile strength

Engineered wood (composite)

-a range of derivative wood products which are manufactured by binding together wood strands, particles, fibers or veneers with adhesives to form composite materials. Sometimes referred to as composite wood or manufactured wood products.

-Advantages:stability/durability/natural aesthetic

Shape Memory Alloys (SMA) (smart material)

-Smart Material. A collection of metal alloys that remember their original cold form shape. Common SMAs are nitinol (titanium/nickel alloy) Used for glasses frames, braces etc. Realtively exspensive

Thermochromic pigments (smart material)

-Pigments that change colour in response to heat

Used for children's products like bottles or bath toys to make sure the milk or water isn't too hot

Photochromic pigments (smart material)

A smart material which changes colour in response to a change in light e.g. sunglasses which tint in sunlight

Electroluminescent wire (smart material)

Thin copper wire coated in a phosphorescent material that glows in response to an alternating current

Used for costumes/lighting for bicycles

Kevlar

-A strong synthetic material used in the construction of protective clothing and equipment.Fibres woven together

-bullet proof/thermal protection/chemical resistant

Precious metal clay

-A modern material which is made up of 99% gold/silver and 1% clay. It can be shaped at room temperature and is used for jewellery

Advantages:easy and quick to work with/set up costs minimal
Disadvantages:can dry out if worked with or stored for to long/not as strong as sterling silver/more expensive

High density modelling form

-Rigid/lightweight and strong material used for high quality 3D models
-Paints can be used on the modelling foam
-can be CNC milled and drilled
-cheap and quick way to make moulds for vacuum forming or casting metals at low temps like pewter

Cellulose paint

-workpiece must be prepared and degreased
-key which adds dents to workpiece so paint grips better
-advantages:dries faster due to solvent/colour/barrier against corrosion
-disadvantages:contains VOCs/dries fast as has solvent/more costs needed

Acrylic paint

-water based/durable/hard-wearing
-require heat/professional equipment/24 hours to cure

Electroplating

an electrolytic process in which a metal ion is reduced and a solid metal is deposited on a surface

Galvanising

-Type of electroplating
-protecting a metal by covering it with a more reactive metal that will corrode first
- zinc carbonate forms when zinc is exposed to air and water,this layer is extremely resistant

Zinc hot dipping method

-type of electroplating
-workpiece gone through a four-stage process to make sure good bond
-workpiece is dipped into molten zinc bath
-then cooled/cleaned up and inspected to make sure even coverage
-advantages:better for larger pieces/give thicker coverage then electroplating

Preservatives

-provide temporary/long term protection
-used in moulds and dies to prevent atmospheric corrosion/condensation build up

Anodising

-mainly used on aluminium to provide a hard-wearing/corrosion resistant surface
-aluminium workpiece is immersed into an acid electrolyte bath and an electric current is passed through
-cathode is inside the tank and the aluminium part acts as the anode

Powder coatings

-provides even cosseting/more hardwearing than paint
-workpiece statically charged and powdered paint sprayed on
-charge creates strong attraction between powder and workpiece
-then baked in an oven where powder coating melts and bonds to metal

Polymer coating

-dip coating provides thick/wear resistant/water resistant/airtight finish
-metal is heated to 230 degrees
-then dipped into tank of fluidised polymer powder as warm air blows into the powder
-the polymer melts and bonds to the surface
-then cooled to solidify the polymer

Aluminium (non-ferrous)

-lightweight
-conductor electrical/thermal
-malleable
-used for drinks cans/kitchen ware

Copper (non-ferrous)

-malleable
-conductor
-corrosion resistant
-used for electrical wire/water pipes

Low carbon steel (ferrous)

-High tensile strength
-ductile
-tough
-used for nuts and bolts/car bodies

Cast iron (ferrous)

-Hard outer layer but brittle core
-machine parts

Brass (non-ferrous alloys)

-low melting points
-good conductor
-corrosion resistant
-used for musical instruments/ornaments

Pewter (non-ferrous alloys)

-malleable
-low melting point
-casts well
- used for sports trophies/decorations

Stainless steel (ferrous alloys)

-corrosion resistant
-hard
-tough
-used for kitchen ware/sinks