Technical aspects of designing and making

2nd Part of A565 Theory

What topics are covered in the exam?

• Designing & Product Planning• Materials• Tools, Equipment & Processes• Computer Applications• Industrial Production• Health & Safety• Quality• Product Evaluation

Theory Questions…1. What are the main stages of the design

process?2. Explain the differences between the 4

different types of strength3. What is the main difference between

softwoods and hardwoods?4. Name 4 good things about MDF5. Why would you put a finish on wood?6. What is the main difference between the 2

different types of plastic?

Designing & Production Planning• Identification of a design need• Analysing a design brief• Research, data and analysis• Identification of complex associations linking principles of good

design and technological knowledge• Developing a design specification• Generating ideas and communicating design

– Modelling and trialing techniques– Digital media and new technologies

• Production planning• Material selection• Make product• Critical evaluation skills

Material PropertiesPerformance characteristics of different materials have to be considered when choosing what products should be made of, you need to know the definitions of the following properties; •Hardness – resist cutting and indentations•Toughness – withstand shocks such as hammering•Strength = 4 types include the ability to withstand...

• Being pulled apart or stretched• Crushed or compressed• Twisted• Sheared as a result of sideways force like scissors

•Elasticity – can be stretched and then return to original length•Flexibility – bend but not break and return to original shape•Ductility – can be stretched into wire•Durable – can withstand bad weather conditions•Malleability – can be hammered, pressed into a shape

Materials - HardwoodsThese come from ‘deciduous’ trees which shed their leaves in autumn. They are generally hard, tough, and durable and are reasonably expensive because they take longer to grow than softwoods.Beech UK, Europe Very tough,

hard, straight, polishes well

Toys, chairs, tools

Oak Europe Heavy, hard, tough, good outdoors, finishes well

High-class furniture, boat building, floors

Mahogany South America, Africa

Easy to work, wide boards available

Indoor furniture, veneers

Materials - Softwoods• Softwoods come from coniferous trees that remain evergreen

all year round• Pine is the most common type;– grown mainly in Northern Europe it is easy to work,

knotty, durable, widely available and cheap– It is most commonly used for construction work and cheap

furniture

Materials – Manufactured boards

• These are wood-based materials that are made by compressing and bonding thin sheets of wood (plywood) or particles (chipboard or MDF) together with adhesive.

• Advantages over solid woods;– More stable as they don’t have grain– Available in large sheet sizes– Easier to buy from DIY shops– Less expensive

THEY DON’T GROW ON TREES!!

Wood Finishes – Protect or DecorateWood Finish Details Example Product

Paints Water-based paints are not durable. Oil-based paints are tough, hard wearing and weatherproof. Acrylic paints are quick drying.

Varnishes Polyurethane varnishes give clear, tough and hard-wearing finish = plastic coating that doesn’t go into wood. Can get them in quick-drying. ‘Yacht’ varnish provides waterproofing.

Stains Do not protect wood. Used to enhance the look of wood by showing off grain or colouring it to look like different, more expensive wood or bright colour. Not easy to apply and can look patchy.

Wax Beeswax is sustainable, natural finish for wood that leaves dull gloss shine. It is applied straight on bare wood after it has been sanded and sealed with oil.

Polishing Build up layers of clear polish, sanding between each coat, which enhances look of grain. Also used to seal wood before waxing.

Materials - PlasticsThere are 2 ‘families’ of plastics;Key Terms;• THERMOPLASTICS = such as acrylic, can be heated to make them

soft so they can be shaped, this can be repeated many times.– PLASTIC MEMORY = is the ability of thermoplastics to return to their

original state after reheating

• THERMOSETTING PLASTICS = such as epoxy resin, can also be heated to make them soft so they can be shaped, but this can only be done once. They are particularly useful for making plastic products that are resistant to heat

• DYES = can be added to plastics to make them a specific colour all the way through unlike woods or metals that can only be coloured on their surface.

Materials – THERMOPLASTICSMetal Picture Properties Uses

Acrylic Stiff, hard, clear, durable outdoors, easily machined and polished, good range of colours, does scratch easily

Illuminated signs, aircraft canopies, perspex sheet, car rear-light clusters, school projects

ABS Tough, high-impact strength, lightweight, scratch-resistant, chemical resistance, excellent appearance and finish. Good for injection moulding

Kitchenware, safety helmets, car parts, telephones, food mixers, toys

Low-density Polythene

Range of colours, tough, flexible, good electrical insulator and chemical resistance

Washing-up liquid, detergent and squeezy bottles, bin liners, carrier bags

Theory Questions…1. What is the main difference between softwoods and

hardwoods?2. Name 4 good things about MDF3. Why would you put a finish on wood?4. What is the main difference between the 2 different types

of plastic?5. What are the 2 parts of Araldite glue (epoxy resin)?6. What are the 2 main types of metals? What are the

differences between them?7. What is the main difference between an alloy and an

element?8. What is ‘work hardening’? And what is the heat treatment

method that you can use to remedy it?9. Name 3 finishes that can be used to stop mild steel from

rusting.

Materials – THERMOSET PLASTICMetal Picture Properties Uses

Urea-Formaldehyde

Stiff, hard, brittle, heat-resistant, good electrical insulator, range of colours

White electrical fittings, domestic appliance parts, wood glue

Epoxy resin Good chemical and wear resistance, resists heat to 250ºC, electrical insulator

Adhesives such as Araldite used to bond different materials such as wood, metal and porcelain

Polyester Resin When laminated with glass fibre becomes tough, hard and strong, brittle without reinforcement

GRP boats, chair shells, car bodies

Materials - MetalsKey Terms;• FERROUS metals contain iron, like steel – they rust and are

magnetic• NON-FERROUS metals don’t contain iron, like aluminium and

copper – they don’t rust and aren’t usually magnetic

ALLOYS are made from mixtures of different elements

PURE METALS are made from one single element

IRON

Materials – FERROUS MetalsMetal Picture Composition Properties Uses

Mild Steel Alloy of iron and 0.15-0.30% carbon

High tensile strength, ductile, tough, poor resistance to corrosion

General purpose, nails, car bodies, nuts & bolts, girders

Stainless Steel Alloy of steel with 18% chrome and 8% nickel

Resistant to corrosion , hard, tough, difficult to work

Sinks, dishes, cutlery, kitchenware

High-speed Steel

Medium-carbon steel with tungsten, chromium, vanadium

Retains hardness at high temps. Can only be ground

Drills, Lathe cutting tools

Materials – NON FERROUS MetalsMetal Picture Composition Properties Uses

Aluminium Pure Metal Light, soft, ductile, malleable, corrosion resistant, polishes well

Aircraft bodies, saucepans, cooking utensils, cans, foils, packaging

Copper Pure Metal Corrosion resistant, malleable, ductile, tough, good conductor of heat and electricity, easily joined

Electrical wire, printed circuits, central heating pipes

Brass Alloy of 65% copper, 35% zinc

Corrosion resistant, heat and electrical conductor, casts well, polishes well

Castings, forgings, ornaments, boat fittings

Heat Treatment of MetalsKey Point – The properties of some metals can be altered to suit particular applications by the use of heat treatment, which involves heating and cooling the metal in a carefully controlled way.

•Hardening – make steel much harder but can be brittle. Do this by heating until cherry red and then quenched in oil.

•Tempering – make steel that has been hardened more tough.Do this by heating to certain temperature

(between 230ºC – 300ºC) and then quench in oil.

•Case hardening – make outer surface of steel very hard. Do this by heating to cherry red, dipping in carbon powder, quench in water.

•Annealing – Relieve problems caused by work hardening (when you hit/bend a metal it can become fragile and

brittle). Do this by heating it to a certain temperature (depending on type of metal) and then allowing it to cool as slowly as possible.

Metal Finishes – Protect or DecorateMetal Finish Details Example Product

Primers and Paints This creates a thin barrier between ferrous metal and oxygen. Must clean surface first and then apply evenly. Primer and then Paint.

Electroplating Ferrous metal is coated in thin layer of non-ferrous metal by fusing it on using electricity. The most common is chrome-plating on car parts.

Anodising Used on aluminium, passing electricity through it thickens an oxide layer on it’s surface. Coloured dyes can be added to process – Maglites.

Dip-coating Heat metal to 180ºC in oven and then dip in thermoplastic powder. Good for making grippy handles on metal tools.

Polishing Polishing compound is added to non-ferrous metal and then buffed to high shine. Can be protected with clear lacquer (spray-on varnish)

Theory Questions…1. What are the 2 parts of Araldite glue (epoxy resin)?2. What are the 2 main types of metals? What are the differences

between them?3. What is the main difference between an alloy and an element?4. What is ‘work hardening’? And what is the heat treatment

method that you can use to remedy it?5. Name 3 finishes that can be used to stop mild steel from rusting.6. What type of material is an SMA? What does it do?7. What is an LCA? Why are they important?8. ‘Knobs’, ‘screws’ and ‘nuts’ are all funny words but what are

they all types of?9. In RM what does the word ‘wasting’ mean?10. What tool is used to make wood and metal components with

cylindrical cross sections?

SMART MaterialsMetal Picture Properties Uses

Shape Memory Alloys

SMAs can be bent to a shape at room temp. but will then return to original shape when heated to certain temp.

Move parts in robots, open and close valves, teeth braces.

Thermochromic pigment

This is paste that can be added to acrylic paint. When it is heated the paint goes clear. When it cools the colour comes back.

Kitchenware, baby feeding spoons, drink stirrers, and childrens’ toys

Thermochromic sheet

This is a black plastic material that when it reaches a certain temperature turns different colours.

Electronic circuitry, food containers, children’s thermometer.

Environmental & Sustainability Issues

You need to know about;• Selection of materials based on a consideration

of the environment and sustainability • The application of the 6Rs: Reduce, Reuse,

Rethink, Refuse, Repair and Recycle.• ‘Life Cycle Analysis’ (LCA). • ‘Design for disassembly’ and the

importance of recovering parts and materials from end-of-life products.

Pre-manufactured Components

SCREWS – ROUND HEAD

SCREWS – COUNTER SINK

NAILS NUTS & BOLTS

KNOCK-DOWN FITTINGS

HINGES KNOBS CATCHES

Design Issues – Making products easy and safe for humans to use

• Anthropometrics– “The measurement of humans”

Design Issues – Making products easy and safe for humans to use

• Ergonomics– Using anthropometric data to design products so

they are easier and more comfortable for humans to use

How is ergonomics involved in the Design Process?

Basic ProductProduct Designer

Anthropometric Data

Ergonomically designed chair

Tools & Processes - WOODTool Picture Use Safety

Pencil Create lines that are clearly visible on wood and can be erased

Sharp point

Steel Rule Measure accurately and draw straight lines

None

Try Square Marks line at 90º to square edge

None

Marking Gauge Scratches parallel lines to edge

Sharp point

MARKING OUT

Tools & Processes - WOODTool Picture Use Safety

Coping Saw Cut curved lines in thin wood and plastic

Sharp blade

Tenon Saw Cut straight lines in thicker wood

Sharp blade

Scroll Saw Same as coping saw but faster because it’s electric

Sharp blade but moves faster. Blade can snap which makes scary BANG!

Band Saw Cuts curved and straight lines very quickly in wood and plastic

VERY DANGEROUS! Not for students as it can cut bits off! You must be trained

WASTING (CUTTING & SHAPING)

Tools & Processes - WOODTool Picture Use Safety

Jig Saw Cut curved lines in wood – good for cutting holes of weird shapes

Must clamp wood down and careful what you are cutting underneath

Hand Drill Cut holes in thin wood, plastic or metal

Not much

Cordless Rechargeable Drill

Cut holes in wood, plastic, wood – VERY MOBILE!

Make sure work doesn’t move – wear goggles, no loose clothes

Pillar Drill Powerful way to drill holes in most things – as long as they fit on bed

Make sure work is clamped – wear goggles, no loose clothes, long hair

WASTING (CUTTING & SHAPING)

Tools & Processes - WOODTool Picture Use Safety

Twist Drill Cut holes in wood, metal and plastic. Fit in a chuck.

Must clamp work down and careful what you are cutting underneath

Saw Tooth Bit (Forstner Bit)

Cut holes in wood which have smooth sides and flat bottoms

Wood can burn and catch fire so drill slowly and clamp strongly

Hole Saw Cuts large discs out of quite thin wood – you can’t stop halfway

Wood can burn and catch fire so drill slowly and clamp strongly

Chuck &Chuck Key

Used to fit drill bits in pillar drills

Make sure chuck is done up tightly and then remove key before turning on!

WASTING (CUTTING & SHAPING)

Tools & Processes - WOODTool Picture Use Safety

Files Shape and smooth metal, plastic and wood. Have lots of ‘teeth’

Clamp work

Chisels Used to cut and shape wood. Often used to make joints. Hit with mallet.

Super sharp! Always point chisel away from body and clamp work

Wood Planes Remove shavings from wood to make surfaces flat and right size.

Plane blade is super sharp so keep away from body and clamp work

Wood-Turning Lathe

Used to make cylindrical shapes and bowls from wood

Big stuff spinning quickly and very sharp tools! Goggles etc.

WASTING (CUTTING & SHAPING)

Tools & Processes - WOODTool Picture Use Safety

Power Router Cutting grooves, fancy edges and complex shapes in wood

Really dangerous because of exposed spinning blade and lots of stuff flying off

CNC Milling MachineExample 1

Cutting really complex shapes very accurately and quickly in wood

Follow safety procedures for machine – all guards working?

WASTING (CUTTING & SHAPING)

Tools & Processes - METALTool Picture Use Safety

Scriber Create lines that are clearly visible on metal by scratching the surface

Sharp point

Centre Punch Marks centre of hole to be drilled by making a dent for bit to fit into

Have to hit it with a hammer – so mind your fingers!

Engineer’s Square Marks line at 90º to square edge

None

Dividers Scratch circles and arcs of different sizes on metal

Sharp points

MARKING OUT

Tools & Processes - METALTool Picture Use Safety

Hack Saw Cut straight lines in metal and plastic – small teeth

Sharp blade

Tin Snips Cut straight lines and curved lines in thin metal sheet

Sharp blades with scissor action

Bench Shears Same straight lines in slightly thicker metal sheet = long handle

Sharp blade with scissor action – very dangerous!

Wire Wool Removes scratches on the surface of metal ready for finishing

Wash hands after so filings do not go in eyes

WASTING (CUTTING & SHAPING)

Tools & Processes – METAL & PLASTIC

Tool Picture Use Safety

Metal Work Lathe Make work with a cylindrical profile

Big stuff spinning quickly and very sharp tools! Goggles etc.

Milling Machine Cut grooves and remove very precise layers of material

Large powered tool with spinning cutter – goggles and guards needed

Vacuum Forming Machine

Mould plastic into different shapes by sucking around mould

Grill area gets hot so keep hands out and don’t touch work until cool

Strip heater Used to bend plastic along a line

Filament gets very hot – wear gloves

WASTING & SHAPING

Theory Questions…1. What type of material is an SMA? What does it do?2. What is an LCA? Why are they important?3. ‘Knobs’, ‘screws’ and ‘nuts’ are all funny words but what are they

all types of?4. In RM what does the word ‘wasting’ mean?5. What tool is used to make wood and metal components with

cylindrical cross sections?6. Which is the simplest wood joint? Why is this weaker than a

hidden-dowel joint? Why are mitre joints sometimes used?7. Why are injection moulding machines used in industry?8. What is the main difference between soldering/brazing and

welding?9. Explain 5 reasons for why CAD is so good10. Explain 3 reasons for why CAM is so good

FIXING – WOOD JOINTSTool Picture Use

Butt Joint The simplest of all wood joints. PVA glue is used to stick plain ends together and then held in place until dry. This is also the weakest joint and usually needs to be strengthened with pins, screws, knock-down fittings, a metal plate etc.

Mitre Joint Pretty simple joint. Ends are cut at 45º and then glued together. Attractive joint as it hides end grain, used for picture and mirror frames. Can be strengthened with nails, screws or staples

Hidden Dowel Joint

More advanced joint – holes need to be drilled in both surfaces and then small dowel is glued in place. Can be used in lots of situations – use this in the exam if you can!!

If you’re keen then check out these other joints – they might ask you to name them (only 1-2 marks)

Tools & Processes – INDUSTRIALTool Picture Use Safety

PLASTICInjection Moulding MachineVideo 1 Video 2

Making lots of identical complicated plastic shapes

Industrial machines have loads of safety equipment and fail safes

PLASTICBlow Moulding Machine

Making hollow plastic shapes like bottles

Industrial machines have loads of safety equipment and fail safes

PLASTIC & METALExtrusion moulding

Make long rods with various cross-section shapes

Industrial machines have loads of safety equipment and fail safes

METALDie-casting

Making lots of complicated metal shapes

Industrial machines have loads of safety equipment and fail safes

Joining MaterialsTool Picture Use Safety

PLASTICTensol Cement

Sticking Plastics together

Nasty stuff – irritant and toxic, wear gloves and goggles

WOODPVA Wood Glue

Gluing wood together – used lots in joints to strengthen them

Not much – clamp work will help join

METALSoldering & Brazing

Its like gluing 2 metals together with metal glue – fairly versatile

Very hot process so gloves, apron etc. need to be worn

METALWelding

Used to permanently melt 2 metals together – very strong but tricky to do

Very hot process so gloves, apron etc. need to be worn. Also need to wear welding mask to protect eyes

Computer Aided Design (CAD)Designers can use computer packages like 2D Design, Autocad, Google SketchUp to design, Model and Test ideas before they go into production. It is particularly useful because;

• Computers can be used to make changes to a design and edit it without having to redraw it.

• Computers can be used to produce very accurate drawings and dimension exactly to what is drawn.

• Computers can produce photorealistic models without having to make them

• You can see what it will look like in 3D – spin it around so you can see all angles

• Computers can show or simulate how a product will behave without having to undertake expensive testing.

Computer Aided Manufacture (CAM)Designers can use machines that are controlled by computers to cut and shape material. They are called Computer Numerically Controlled (CNC). This is good news because;• Computers do not make mistakes if programmed

properly.• Computers give reliable and consistently high standards

of manufacture.• Computers achieve quicker production times. Complex

shapes and designs can be created easily.• CNC Lathe• CNC Miller/Router• Laser Cutter

Theory Questions…1. Which is the simplest wood joint? Why is this weaker than a

hidden-dowel joint? Why are mitre joints sometimes used?2. Why are injection moulding machines used in industry?3. What is the main difference between soldering/brazing and

welding?4. Explain 5 reasons for why CAD is so good5. Explain 3 reasons for why CAM is so good6. What is main differences between; one-off, batch, and mass

production?7. How does rapid-prototyping work?8. What is Globalisation? Why is it a good/bad thing?9. Give 5 examples of health & safety equipment that could be used

in a factory.10. What does the ‘corrosive’ safety symbol look like?

One-off ProductionUsed to produce one or two very special products, usually by highly skilled craftsmen who are paid lots of money. It is very time-consuming as each part is made individually and therefore is very expensive. Products have a ‘hand made’ feel and therefore are usually considered high quality.

Basic Production MethodsWhat we do to a material in order to make something is called a process, but a method is how we apply that process to manufacture one or more products. A designer has to decide which production method should be used to make their products based on the numbers and quality required. There are 3 main methods;

Batch ProductionBatch production is used where a number of identical products are made, and special tools are normally used to make them. The size of the batch can be anything from 10 – 10000 but can be repeated at any time if more orders are made. Production processes like injection-moulding and die-casting are often used as once the moulds are made for the parts they will be suitable for future re-orders. These moulds are expensive to make at first but this cost is spread over the number of products made so becomes cheaper as more are made.The workers are not as skilled as those in one-off production and therefore are paid less. Using moulds, jigs and templates improves consistency but as products are usually hand assembled by low-skilled workers this can result in lower build quality.

High-Volume ProductionSometimes referred to as ‘mass-production’ – this deals with the production of very large numbers of identical products. A lot of specialist equipment is needed and it is very expensive to set up therefore it is only economical to use this method if large numbers of products are made.This is a very fast method of production and only a few skilled workers are needed to maintain and manage the machine. Assembly lines are often used which keep production almost continuous. Robots are used to improve build quality, accuracy and consistency. This type of production was first used by Henry Ford when he made the Model T.

Rapid PrototypingCAD packages allow the designer to view a 3D image of a new design on-screen. A number of systems are now available to quickly turn these designs into models which can be handled and used for market research purposes.These machines are called rapid-prototypers. First computer software breaks the 3D drawing into thin horizontal slices. These ‘layers’ are then sent to the machine in sequence where they are built up to make the model.One of these rapid-prototyping systems is called stereo-lithography which uses a laser to harden layers of liquid plastic resin to make the 3d shape.

GlobalisationThis is where companies become multi-national, this means they make products in countries all over the world and can also sell their products all over the world.This is good because;• They can make products cheaper as labour costs are often less and also they are closer to raw materials• Factories can be closer to new markets – for example Nissan (Japan) make cars in the UK to sell in Europe to save on transport costsIt can be bad because;• Labour laws in emerging economies (like China, India etc.) are not as strict and this can lead to mis-treatment of workers

• Companies often have to ship products long distances which can be very bad for the environment because of all the CO2 produced

Health & SafetyUnderstand the importance of personal safety when engaged in designing and making activities, including: • Personal protective equipment • Machine guards • Dust and fume extraction • Waste disposalUse the link above to learn theory and complete activity

You also need to know about simple risk assessmentRisk = (How dangerous it is) X (How likely it is to happen)

C.O.S.H.H.Control of Substances Hazardous to HealthThe COSHH Regulations (2002) states general requirements on employers to protect employees and other persons from the hazards of substances used at work by risk assessment, control of exposure, health surveillance and incident planning. There are also duties on employees’ to take care of their own exposure to hazardous substances and prohibitions on the import of certain substances into the European Economic Area.

Safety Symbols• Blue signs are mandatory – you must do what they

say

• Black and Yellow signs are warnings

• Red diamonds are warnings of hazards

Quality It is important that you know that products need to be a certain quality to be sold

commercially.

• Design – they have to be designed in such a way that they will perform the correct function

• Manufacture – they need to be made so they are both safe and don’t fall apart.

– To do this the correct materials need to be chosen and the product must be made accurately

Quality Control

To help with this process companies will check a certain number of the products. This is called inspection, and would generally include checks on;

– Accuracy of sizes

– Overall appearance

– Surface finish

– The consistency, composition, and structure of the materials