Technical aspects of designing and making

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… What are the main stages of the design process?
Explain the differences between the 4 different types of strength What is the main difference between softwoods and hardwoods? Name 4 good things about MDF Why would you put a finish on wood? 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 Properties Performance 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 - Hardwoods These 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 Decorate
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 - Plastics There 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 – THERMOPLASTICS
Metal 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… What is the main difference between softwoods and hardwoods? Name 4 good things about MDF Why would you put a finish on wood? What is the main difference between the 2 different types of plastic? What are the 2 parts of Araldite glue (epoxy resin)? What are the 2 main types of metals? What are the differences between them? What is the main difference between an alloy and an element? What is ‘work hardening’? And what is the heat treatment method that you can use to remedy it? Name 3 finishes that can be used to stop mild steel from rusting.

Materials – THERMOSET PLASTIC
Metal 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

IRON Materials - Metals Key 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 IRON PURE METALS are made from one single element ALLOYS are made from mixtures of different elements

Materials – FERROUS Metals
Picture Composition Properties Uses Mild Steel Alloy of iron and % 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 Metals
Picture Composition Properties Uses Aluminium Pure Metal Light, soft, ductile, malleable, corrosion resistant, polishes well Aircraft bodies, saucepans, cooking utensils, cans, foils, packaging Copper 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 Metals
Key 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 Decorate
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… What are the 2 parts of Araldite glue (epoxy resin)?
What are the 2 main types of metals? What are the differences between them? What is the main difference between an alloy and an element? What is ‘work hardening’? And what is the heat treatment method that you can use to remedy it? Name 3 finishes that can be used to stop mild steel from rusting. What type of material is an SMA? What does it do? What is an LCA? Why are they important? ‘Knobs’, ‘screws’ and ‘nuts’ are all funny words but what are they all types of? In RM what does the word ‘wasting’ mean? What tool is used to make wood and metal components with cylindrical cross sections?

SMART Materials Metal 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 Product Anthropometric Data Product Designer Ergonomically designed chair

Tools & Processes - WOOD
MARKING OUT Tool 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 Marking Gauge Scratches parallel lines to edge

WASTING (CUTTING & SHAPING) Tool Picture Use Safety Coping Saw Cut curved lines in thin wood and plastic Sharp blade Tenon Saw Cut straight lines in thicker wood 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) Tool 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) Tool 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 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) Tool 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) Tool 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 Machine Example 1 Cutting really complex shapes very accurately and quickly in wood Follow safety procedures for machine – all guards working?

Tools & Processes - METAL
MARKING OUT Tool 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

Tools & Processes - METAL
WASTING (CUTTING & SHAPING) Tool 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

Tools & Processes – METAL & PLASTIC
WASTING & SHAPING 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

Theory Questions… What type of material is an SMA? What does it do?
What is an LCA? Why are they important? ‘Knobs’, ‘screws’ and ‘nuts’ are all funny words but what are they all types of? In RM what does the word ‘wasting’ mean? What tool is used to make wood and metal components with cylindrical cross sections? Which is the simplest wood joint? Why is this weaker than a hidden-dowel joint? Why are mitre joints sometimes used? Why are injection moulding machines used in industry? What is the main difference between soldering/brazing and welding? Explain 5 reasons for why CAD is so good Explain 3 reasons for why CAM is so good

FIXING – WOOD JOINTS Tool 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 – INDUSTRIAL
Picture Use Safety PLASTIC Injection Moulding Machine Video 1 Video 2 Making lots of identical complicated plastic shapes Industrial machines have loads of safety equipment and fail safes Blow Moulding Machine Making hollow plastic shapes like bottles PLASTIC & METAL Extrusion moulding Make long rods with various cross-section shapes METAL Die-casting Making lots of complicated metal shapes

Joining Materials Tool Picture Use Safety PLASTIC Tensol Cement
Sticking Plastics together Nasty stuff – irritant and toxic, wear gloves and goggles WOOD PVA Wood Glue Gluing wood together – used lots in joints to strengthen them Not much – clamp work will help join METAL Soldering & Brazing Its like gluing 2 metals together with metal glue – fairly versatile Very hot process so gloves, apron etc. need to be worn Welding 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… Which is the simplest wood joint? Why is this weaker than a hidden-dowel joint? Why are mitre joints sometimes used? Why are injection moulding machines used in industry? What is the main difference between soldering/brazing and welding? Explain 5 reasons for why CAD is so good Explain 3 reasons for why CAM is so good What is main differences between; one-off, batch, and mass production? How does rapid-prototyping work? What is Globalisation? Why is it a good/bad thing? Give 5 examples of health & safety equipment that could be used in a factory. What does the ‘corrosive’ safety symbol look like?

Basic Production Methods
What 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; One-off Production Used 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.

Batch Production Batch 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 – 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 Production
Sometimes 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 Prototyping CAD 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.

Globalisation This 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 costs It 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 & Safety Understand the importance of personal safety when engaged in designing and making activities, including: Personal protective equipment Machine guards Dust and fume extraction Waste disposal Use the link above to learn theory and complete activity You also need to know about simple risk assessment Risk = (How dangerous it is) X (How likely it is to happen)

C.O.S.H.H. Control of Substances Hazardous to Health
The 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

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