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Flashcards

AS DT Revision 2

Aidan Magee English 148 cards

Vacuum Forming Diagram

Cards in this deck (148)

  1. 1Advantages of Vacuum Forming• Ideal for batch production: inexpensive
    • Relatively easy to make moulds that can be modified
  2. 2Advantages of Vacuum Forming• Mould needs to be accurate to prevent webbing from occurring
    • Large amounts of waste material produced
  3. 3Applications of Vacuum FormingPolymers used
    • Acrylic, HIPS, PVC
    Applications
    • Yoghurt pots, trays, insides of fridges
  4. 4Features of a successful Vacuum Form• Draft angle/tapers
    • Rounded/radiused corners/edges
    • Vent holes
    • Depth of draw
    • Internal draws must have vent holes
    • Positioning of features to avoid webbing
    • No undercuts
    • High quality surface finish
    • Resistance to heat
    • Durable mould
  5. 5Vacuum Forming DiagramVacuum Forming Diagram
  6. 6Rotational MouldingA process that produces hollow one-piece components.
    • Mould is opened and filled with plastic powder (1)
    • Mould is rotated around a central point in three planes 360 degrees) (1)
    • Heated to melt the plastic powder (1)
    • Plastic is evenly distributed throughout the mould (1)
    • Mould continues to rotate (1) and is cooled to solidify the plastic (1)
    • Mould is opened and product removed {1}
  7. 7Rotational Moulding Advantages• Easy to produce large products
    • End product has no seams
    • Wall of product is uniform thickness
    • Corners of product are stress free
    • Colour integrally part of product
    • Metal inserts can be included in the moulding
    • Products are near-net-shape and rarely need further finishing.
  8. 8Rotational Moulding Disadvantages• Lower volume production
    • Materials available are limited
    • Can be labour intensive when compared with injection moulding
    • The long cycle times usually limit economic batch sizes to between 500 and 10,000.
  9. 9Rotational Moulding Applications• Buckets
    • Plastic footballs
    • Dustbins
    • Oil drums
    • Storage tanks
    • Traffic cones
  10. 10Jigs• Enable repetitive accuracy / reduction in errors leading to less faulty / wasted components and materials.
    • Components are easily /quickly aligned / no marking out which speeds up production / saves time.
    • Enable less skilled personnel to carry out the tasks reduced labour costs
  11. 11PatternsPatterns are replicas of products, usually made from wood that are produced for casting. Pattern making is a highly skilled job as many factors need to be considered to ensure that the cast item is produced to the correct size with no faults or blemishes.
    Patterns must be carefully designed to ensure that they can be removed from the sand successfully. They should allow for contraction of the metal and should take into consideration cores and holes that might be required on the finished product.
  12. 12FormersFormers are used in processes such as vacuum forming and laminating.
    Formers are shapes around which material can be bent or formed in order to create, in some instances, quite complex components.
  13. 13Formers Advantages and DisadvantagesThey can be used to create innovative work, or example if a designer wishes to create a piece of plywood furniture with sweeping curves, then the material can be shaped using formers.
    A disadvantage of using formers for complex constructions is that they can be cumbersome and difficult to handle.
  14. 14MouldsMoulds are the ‘negative’ in processes such as casting, injection moulding and blow moulding.
    • The mould is where the molten metal or molten plastic is either poured or forced in order to make the desired shape. ln casting the mould might be made from sand or hardened steel.
  15. 15Nuts and boltsAdvantages
    • Can be applied and removed an infinite number of times
    Disadvantages
    • Prone to vibration
    Applications
    • Engineering situations where joint needs to be undone
  16. 16WashersWashers are thin disks, usually of metal, but can be of plastic or other materials, with a hole through the centre that are often used in conjunction with nuts and bolts.
    • To act as a locking device / prevent a component working loose under vibration. (1)
    • To maintain pressure / tension / take up slack where a components needs to remain adjustable / loose.
  17. 17RivetsRivets are used to make permanent joints in metal. The two main types of rivet are solid and pop.
    Solid rivets come in two forms, snap (round head) and countersunk head.
    Pop rivets come in only one form but in various sizes.
  18. 18Snap RivetsStage 1
    • Mark out the positions
    • Drill the holes through the material in desired positions
    Stage 2
    • Clean off burrs and waste material
    Stage 3
    • Place the rivet through the holes and support the round head of the rivet in the snap which has been secured in the machine vice.
    Stage 4
    • Check the length of the shaft of the rivet
    • There should be 1/2 times the diameter above the work to be joined
    Stage 5
    • Use the hammer to shape the rivet into a round head
    Stage 6
    • Finish off using the snap and hammer to make the rivet a smooth round shape
  19. 19Snap Rivets 1Snap rivets
    Advantages
    • Good, strong joint
    Disadvantages
    • Access to both sides of materials being joined required
    Applications
    • Engineering situations where permanent joint is required
  20. 20Snap Rivet ProcessSnap rivet Process
    • Holes are drilled to suit rivet diameter (1)
    • Rivet cut to correct length (1)
    • The head is supported in a ‘rivet set’ (dolly) (1)
    • The rivet set squashes the two pieces of metal together removing any gap (1)
    • The end of the rivet is rounded over (1) using the ball pein of the hammer (1)
    • Surplus rivet is either filed off (if countersunk) (1) or rounded using a ‘rivet set’ (dolly) (1)
  21. 21Snap Rivet DiagramSnap Rivet Diagram
  22. 22Countersunk head rivetsCountersunk head rivets
    Countersunk head rivets are used where it is important that the head of the rivet is flush with the surface of the materials being joined.
    Stage 1
    • Drill the holes through the material in the desired positions on both of the outside faces of the join
    Stage 2
    • Remove any burrs and waste material
    Stage 3
    • Place the rivets into the hole and press the metal to be joined together
    Stage 4
    • Place the countersunk head on flat metal surface
    Stage 5
    • Hit the rivet with the flat face of the hammer to swell the rivet
    Stage 6
    • Use the ball-pein of the hammer to force the rivet into the countersink
    Stage 7
    • Finish off with the flat face of the hammer and then smooth off with a file
    • When a countersunk rivet has been used the work should be filed flush so that it is virtually impossible to see the rivet.
  23. 23Pop RivetingWith solid riveting, both sides of the work need to be accessible. There are occasions however, when working on both sides of the material is either impractical or impossible; in such cases, pop riveting is used.
    To pop rivet, a pop rivet gun is used. The pop rivet itself is hollow and has running through its centre a piece of wire called a mandrel.
    • The rivet is placed into the holes in the pieces of metal to be joined and the rivet gun is used to pull the mandrel through the centre of the rivet.
    • As the mandrel is being pulled, the end of the inner side of the rivet begins to expand, pulling the two sheets together.
    • Eventually, when the rivet has been pulled to its limit, the mandrel snaps and leaves the rivet securely in position.
  24. 24Pop Riveting AdvantagesAdvantages
    • Can be applied from one side
    • Pop rivets could be used as it is a quick process therefore saving assembly time/money/labour
    • Pop rivets are sometimes used to tack work together prior to welding because they are quick/cheap/easy to remove
  25. 25Pop Riveting DisadvantagesDisadvantages
    • Relatively weak when compared to snap rivets
    Applications
    • Joining thin sheet metal
  26. 26WeldingWelding is another method of joining metal, this time using heat.
    A weld is a ‘fusion’ joint. This means that the two pieces of metal are literally melted together. At the end of the process the two parts that have been joined literally become the same component.
    There are two types of welding — oxyacetylene welding and arc welding.
  27. 27Oxyacetylene weldingWith oxyacetylene welding, the two gases oxygen and acetylene are mixed in a gas torch, ignited and used as the source of heat. A filler rod of the same material is often used to complete the joint. At the end of the process the joint should be as strong as the parent metal.
  28. 28Welding Advantages and DisadvantagesAdvantages
    • Weld is as strong as parent metal
    Disadvantages
    • Can be safety issues with both gas welding and MIG welding
    General engineering, Automotive engineering
  29. 29Metal lnert Gas (MIG)Metal lnert Gas (MIG) welding is a form of electric arc welding. MIG welding involves a process where, using an electric current, an arc is struck between the work and an electrode and this is used as the heat source. The filler is in the form of thin wire and as the welding progresses the wire gradually is fed into the joint and is used up. During the operation a flow of inert gas, usually argon, is made to flow over the area being joined. The inert gas acts as an envelope that keeps oxygen away from the joint. This prevents oxidation on the joint and therefore helps to make the weld sound. This process is ideal for use on materials that cannot be gas welded, for example, aluminium.
  30. 30Metal lnert Gas (MIG) welding processProcess
    • The work is electrically connected to the earthing cable.
    • An electrical spark.
    • A filler wire / electrode is fed through the gun.
    • The materials are melted / molten / fused together.
    • Argon gas / gas shield is fed over the weld pool.
  31. 31Mig Welding DiagramMig Welding Diagram
  32. 32Brazing• Brazing is a method of joining mild steel to mild steel using heat and a second material called spelter.
    • Pelter is an alloy of copper (65 per cent) and zinc (35 per cent) and has a melting point of 875°C:
  33. 33Brazing• The surfaces to be brazed are cleaned with an abrasive
    • The two surfaces are fluxed
    • The components are place together and wired/clamped in place
    • The metal is heated evenly to allow the flow of brazing spelter around the whole joint
    • Brazing spelter is applied to the joint
    • The joint is allowed to cool until the brazing spelter is set
  34. 34Brazing Advantages and DisadvantagesAdvantages
    • Good general purpose joint
    • Can be undertaken with little training
    Disadvantages
    • Care needed when undertaking braze to ensure joint is clean and oxides do not form creating weak joint
  35. 35Hard Soldering Process• Metal cleaned with an abrasive
    • Work clamped / wired together
    • Flux applied
    • Heat applied
    • The solder cut up/applied/fed-in
    • A stated temperature between 625 - 8000C
    • Solder melts / flows round the joint
  36. 36Hard Soldering Advantages and DisadvantagesAdvantages
    • Relatively low temperatures required
    • Comes with different melting points to enable complex decorative pieces to be produced
    Disadvantages
    • Weak joint does not withstand ' stress
    Used for Decorative metalworking
  37. 37Tensol CementTensol cement is used to join thermoplastics
    Tensol cement should be applied to both surfaces of the thermoplastic to be joined and then the component parts should be pushed together. The join then needs to be held carefully together. Ideally the join should be clamped together for up to 24 hours. The result is a permanentjoint.
    It should be stressed that as Tensol cement is a solvent it gives off fumes and should therefore be used with caution. it is regarded as a hazardous substance.
  38. 38Tensol Cement Advantages and DisadvantagesAdvantages
    • Gives excellent bond when joining acrylic
    Disadvantages
    • It must be applied with care to avoid damage to surface of acrylic
    • Gives off strong fumes
    Applications
    • Joining acrylic
  39. 39Polystyrene CementThe cement contains a solvent that melts the surface of the plastics being joined. This allows the two component parts to fuse together.
    As the solvent evaporates the strength returns to the plastic. Like Tensol cement, any parts being joined need to be held together until set.
    lt should be remembered that only thermoplastics can be joined with Tensol cement or polystyrene cement.
    Polystyrene cement ' Gives excellent bond ° It must be applied with care to ' Joining polystyrene
    when joining two pieces of avoid melting poiystyrene '
  40. 40PVA GlueProcess
    • Apply to surface.
    • Two pieces are clamp/rubbed together.
    • Clean off excess with water.
    • Leave to cure / dry.
  41. 41PVA Glue Advantages and DisadvantagesAdvantages
    • Produces strong bond when joining wood
    • Can be used on cards and papers
    Disadvantages
    • Can take up to 24 hours to bond wood
    • Requires clamps to hold work in position whilst hardening
    Applications
    • Wood joints
  42. 42Epoxy ResinEpoxy-resin is a thermosetting plastic resin that cures, or goes hard, when mixed with a catalyst or hardener. Once the two materials, resin and catalyst come in contact with each other, a chemical reaction begins and the resin begins to go hard. This reaction is not reversible so once‘ it starts it cannot be stopped.
    To use an epoxy-resin, equal quantities of resin and catalyst are squeezed out of their tubes onto a piece of scrap wood or metal and then mixed together. Once they are completely mixed, the resultant paste can be applied to the surfaces being joined
  43. 43Epoxy Resin Advantages and DisadvantagesAdvantages
    • Very strong
    • Waterproof
    • Heat and chemical resistant
    Disadvantages
    • Takes time to cure and harden
    • Requires two elements: resin and catalyst
    Applications
    • Aircraft, Boats , Golf clubs, Skis
  44. 44Contact AdhesiveAs with all gluing processes, the first thing to remember when using contact adhesives is to make sure that the surfaces being bonded are perfectly clean and free from dust.
    Contact adhesives need to be applied to both surfaces being joined. The adhesive must be applied thinly on those surfaces and then left to dry for a few minutes.
    Once the adhesive is dry the two surfaces can be pushed together. When the two elements come into contact with each other the bonding occurs almost immediately. This instantaneous bonding is useful as no clamping is required though, it does mean that once contact is made between the components it is impossible to adjust the join. Contact adhesive must be used in well-ventilated areas as it gives off toxic fumes.
  45. 45Contact Adhesive Process• Adhesive is applied to both surfaces to be bonded
    • The adhesive is allowed to dry until tacky/touch dry
    • The surfaces are brought together forming an instant bond
    • The surface can be ‘hammered’ using a veneer hammer to smooth out any imperfections
  46. 46Contact Adhesive Advantages• Instant/rapid bond therefore saving time on assembly
    • Ideal for curved surfaces which are awkward to apply pressure to therefore avoiding the need for costly jigs/formers
    • Ideal for large surface areas therefore avoiding the need for large and expensive presses
    • Contact adhesives can be applied to a wide range of materials therefore making the joining of dissimilar materials possible
  47. 47Contact Adhesive DisadvantagesDisadvantages
    • Cannot be adjusted during joining
    Applications
    • Applying Formica® and veneers
  48. 48Hot Melt Glue AdvantagesHot melt glue is the glue that is used in glue guns.
    Advantages
    • Good bond when used in model making
    • Relatively Quick to harden and bond
    • Sets quickly
    • No clamping needed
    • Effective on a wide range of materials
    • Sufficient strength for a model
    • Good gap filler
  49. 49Hot Melt Glue DisadvantagesDisadvantages
    • Safety issues: glue gun can be very hot and can burn
    Applications
    • Model making
  50. 50Metalworking sawsThe principal metalworking saw is the hacksaw.
    A hacksaw blade is classified by the number of teeth per 25mm, and the most common size used for general purpose cutting is a blade that has 25 teeth per 25mm.
    A smaller version of the hacksaw is the ‘junior’ hacksaw. This is used for more intricate cutting.
  51. 51Woodworking sawsIf you wish to cut along the grain, you need a large saw with big teeth that can remove the waste material such as a rip saw.
    To cut across the grain, you would use a cross—cut saw. These have slightly smaller teeth. For small accurate work like cutting out joints, a back saw would be used.
    The tenon saw is an example of a back saw. With back saws, the blade has a strengthening piece of steel or brass along the top of the blade to keep it rigid whilst cutting.
  52. 52Types of sawsHacksaw
    • General purpose metal saw
    Junior Hacksaw
    • Small general purpose saw for most metals
    Rip Saw
    • Sawing along the grain of large pieces of wood
    Cross cut saw
    • Sawing across the grain of large pieces of timber
    Tenon saw
    • Producing joints and work on small pieces of wood
  53. 53AbradingAbrading is the wearing down or rubbing away of material.
    ln terms of Resistant Materials Technology this means filing, grinding and sanding.
  54. 54FilingFiling
    Filing is a method of removing metal.
    The most common file is the hand file. This has a rectangular cross section and has parallel sides.
    Other files include round, half-round, square and triangular cross sections.
    the rasp, is for using on wood
  55. 55Grinding• There are three types of grinding: offhand, disk and surface.
    Offhand grinding is where a machine which is either mounted on a bench or on the floor powers a grinding wheel. These are often found in school workshops and are used for sharpening tools such as chisels.
    A disk grinder is held in the hand and is used as a portable unit and these are usually used as a finishing off tool, perhaps for grinding down a weld.
  56. 56SandpaperSandpaper is a general term that is used to describe paper that has abrasive grit glued onto a backing sheet.
    The correct term to use is actually ‘glasspaper’
    Glass-paper is classified by number and ranges from 4O the coarsest (roughest) to 400 (smoothest) which is incredibly fine.
  57. 57Emery clothThe equivalent abrasive in metalworking is emery cloth. Like glasspaper, emery cloth comes in various grades and when using emery the most abrasive should be used first, going down to the finest to finish off.
  58. 58Work HardeningWork hardening occurs when a non-ferrous metal is cold worked. This means it is bent, hit or shaped over a period of time. As the material is shaped it becomes so hard and brittle that it can eventually fracture.
    Once the desired shape has been achieved, in order to keep it in that shape, it needs to be hardened. in order to do that, the work would be plannished — that is hit gently with a hammer to work harden the copper to stop the dish bending
  59. 59AnnealingAnnealing is a heat process whereby a metal is heated to a specific temperature /colour and then allowed to cool slowly
    When a piece of metal is work hardened and the material becomes very difficult to bend and shape, it becomes necessary to relieve the stresses that have been built up inside the metal. The process used to relieve the internal stresses within non-ferrous metals and make them workable again is called annealing. Different metals are annealed in different ways but all methods of annealing involve the application of heat.
  60. 60AnnealingGreat care should be taken when annealing and the correct protective clothes, such as aprons, gloves and goggles should be worn. Once metal has been annealed it can once again be worked and “manipulated. However, if the metal again becomes work hardened it may well need to be re-annealed. ln fact the process may well need to be carried out a number of times during the manufacture of a single item.
  61. 61NormalisingNormalising is a process that is undertaken on ferrous metals that have become hardened, in order to return them to their original unhardened state. When medium or high carbon steel is heated to its critical temperature, then plunged into water, it will harden. lf an attempt is made to cut or drill the material when it is in this state, the hacksaw or drill will soon become blunt. ln order to remove the hardness, the steel must be normalised. The steel is heated until it is cherry red, 900°C hot and then allowed to cool down in air. Once the steel has cooled it will have lost some of its hardness and can, once again, be cut or drilled.
  62. 62HardeningHardening process
    1. Heat to bright red /above 800 deg/above critical point high temperature. (1)
    2. Cooled fast / quenched / in water / oil
  63. 63Hardening 2Why is a blade hardened?
    • To retain a sharp edge
    • harder than the material to be cut
    • reduce wear
  64. 64Tempering Process• The metal is heated (Not to ‘red hot’)
    • The temperatures are signified by the changing colour of the metal when heated
    • The metal is then quenched in water
  65. 65Tempering• It is tempered to remove some of the brittleness
    • to increase the toughness of the blade
    • making the blade more flexible
    • reduce the chances of it snapping
    • withstand impact
    • Hardening makes the blade brittle (stressed)
    • Tempering reduce brittleness (stress)
    • Increase toughness
    • So the blade/teeth will not snap / makes the blade more durable when in use
  66. 66ConversionAs soon as possible after a tree has been felled, it needs to be converted. Conversion is the term used to describe the process of changing the wood in the tree into usable planks of timber. There are two common methods of converting timber, the through and through (slab) method and the quarter sawn method.
  67. 67Through and through (slab) sawn conversionThe through and through (slab) method is the simplest method of conversion and involves cutting the timber along the complete length of the log. The result is long planks of parallel cut wood. The advantage of this method is that it is seen as a relatively cheap way of converting timber and there is little waste. However, there is a downside. The final planks, because of the arrangement of the annual rings, may be prone to warping and cupping. This method is more often used in the conversion of softwoods
  68. 68Quarter sawn conversionQuarter sawn conversion is a more expensive method of conversion than the through and through method. This is due to the fact that there is far more wastage. The timber is cut in such a way so as to make the annual rings as short as possible. This reduces the risk of the wood twisting or cupping As a consequence of this quarter sawn converted timber is usually regarded as higher quality than through and through converted timber
  69. 69DiagramDiagram
  70. 70Why is through and through (slab) better than quarter?1. Faster conversion rate.
    2. No need to keep re-positioning the log / simple cut pattern / cuts all run in the same direction / less cuts.
    3. Cheaper conversion method.
    4. Whole / more of the log is used
    5. Little waste produced.
    6. More planks produced / available for sale.
    7. Planks are taken from the whole log width.
    8. Wider planks produced.
    9. Less edge jointing / manufacturing processes needed.
    10.Less skilled labour needed.
    11.Fewer trees cut down / reduced deforestation / more eco-friendly / sustainable.
  71. 71Why is quarter better than through and through (slab)?1. Produces a higher quality plank (1) which is more stable / less likely to warp/bow/ twist/ cup /split (1) as annual rings are closer/ cross grain is shorter. (1)
    2. Produces more valuable timber (1) as the figure of the grain is exposed (1) giving improved aesthetics.
  72. 72SeasoningSeasoning is the removal of excess moisture from timber after the timber has been felled and converted into usable planks. There are two different types of seasoning: natural seasoning and kiln seasoning.
  73. 73Natural seasoningNatural seasoning is where the timber is allowed to dry out at its own pace in air. In natural seasoning the timber, once cut into planks, is stacked. Sticks are placed between the layers of planks to separate them and to allow air to circulate around the wood.
    The stack is raised off the ground and has a roof put over it to protect it from the worst of the weather. The ends of the planks are painted to prevent the ends drying out faster than the rest of the timber. The stack is then left to allow the timber to dry out slowly.
  74. 74Natural seasoning Advantages and DisadvantagesThis is the cheapest method of seasoning, but it does have some disadvantages. As the process is urdertaken in totally uncontrolled conditions, there is no way of establishing the water content of the timber and there could be some inconsistency with the final product. Anotn.er disadvantage is that it can take up to 5 years for the wood to season and dry out ready for use. As a general rule, wood is seasoned for one year for every 25mm of thickness of timber.
  75. 75Kiln seasoningKiln seasoning is where timber is dried out artificially’ in a kiln. The planks of wood are stacked on a trolley with small pieces of wood to separate the layers.
    The trolley is then rolled into the kiln and the kiln is then sealed. Once the wood is in the kiln, steam is pumped into the chamber. This has two effects.
    • Firstly, it kills off any bugs and insects that may be in the timber.
    • Secondly, it has the effect of forcing moisture from the cells in the wood, which ensures that the moisture content is the same throughout the timber.
  76. 76Kiln seasoning 2Once this has been done, the steam level is reduced and the temperature gradually increased. This dries out the wood. At the end of the process a flow of almost dry air is pumped into the kiln. This process ensures that the timber is seasoned in a completely controlled way.
    When the timber is withdrawn from the kiln the moisture content is usually below 12 per cent, which makes it suitable for most applications.
  77. 77Kiln seasoning advantages and disadvantagesThe advantages of kiln seasoning is that it is far quicker than drying out wood naturally and because the moisture content can be controlled, the resulting timber is very stable.
    The disadvantage of kiln seasoning is economic. lt is far more expensive than natural seasoning.
  78. 78Why kiln seasoning is better than natural• The level of moisture in the wood can be controlled accurately (1) resulting in a more reliable/consistent/even moisture content (1)
    • The moisture level can be reduced to a lower/guaranteed level (1) which means the timber can be used in drier environments (1)
    • The speed of the drying is much quicker (1) meaning capital is tied up for a shorter period/timber gets to the customer more quickly (1)
    • Kiln seasoning is done at a higher temperature (1) therefore increasing the effective eradication of infestation in the timber
    • Kiln seasoning takes up less spacetherefore reducing the need for large premises
    • Kiln seasoning is equally effective all year round/not seasonal (1) therefore supplier is consistently able to meet customer demand
  79. 79Faults in woodAs wood is a natural material it can be prone to problems. Cupping
    Problems can result from a number of factors. lt might be issues with seasoning where uneven drying can cause faults, or it might be as a result of biological or fungal attack.
    lt is always a good idea to check timber thoroughly before using it. Poor-quality timber can affect the final outcome of what otherwise would have been a high- quality product.
  80. 80CuppingA piece of timber is said to be cupped when it is bent across the grain. When a plank of wood is viewed from the end the annual rings can be clearly seen. Some rings are longer than others. The longest rings are those that are furthest away from the centre of the tree.
    The varying length of annual rings causes the wood to dry out at varying speeds. This varying rate of drying causes different parts of the wood to shrink at different rates.
    The result of this difference in drying rates causes the wood to cup.
  81. 81TwistingIf timber is used that comes from the centre of the tree there is sometimes a danger that the wood has a spiral grain. This spiral grain can cause the timber to twist as it dries out. A piece of wood that is twisted resembles a Propeller and is usually unusable.
  82. 82Cupping and TwistingCupping and Twisting
  83. 83SplittingSplitting is when the grain of the timber separates. This usually occurs at either end of a plank of wood. The only thing to do when this happens is to cut off the affected ends of the plank.
  84. 84KnotsThe knots in timber are where branches were attached to the tree. The tree has continued to grow and wood has covered the point where the branch was. Knots can cause a problem. Sometimes they become loose and drop out. This can be extremely dangerous if the wood is being machined. lt is therefore advisable to check for knots when selecting material and avoid timber that has them.
    Knots occur because As the tree grows it produces branches
    The grain of the branch runs at a different angle to that of the trunk resulting in a knot
  85. 852D designing and modificationAdvantages
    • Highly accurate drawings
    • Easy to edit drawings
    • Easy to store drawings
    Disadvantages
    • High cost of set-up
    • Files can be lost if system if not backed up
    • High-quality training required
  86. 863D virtual modelling AdvantagesAdvantages
    • Can clearly see around an object 360 degrees
    • The models can be manipulated/changed/edited quickly
    • The costs involved are relatively low compared to a physical model
    • The models can be distributed electronically e.g. to e-mail/to CNC machine / to RPT machine
    • The models can be stored electronically
    • Virtual testing/simulation is possible
    • They can be used to produce photorealistic/realistic images
    • Relatively quick to produce
    • Viewable from a range of angles/manoeuvrable image
    • Models can be replicated easily/giving multiple options
  87. 873D virtual modelling DisadvantagesDisadvantages
    • High set-up costs
    • Training is required as software gets updated
    • Trained technicians are needed to set up software/hardware
  88. 88Block modelling 1Block modelling is a very useful tool for helping to determine the shape, dimension and surface details by constructing an accurate representation of a final product.
    Block models have no working or moving parts and are thus concept models of the product that is being, or has been, designed.
    The models can be extremely useful in determining the ergonomic factors of many products. By constructing a number of block models of various shapes and sizes it is possible for designers to literally ‘get a feel’ for the product.
  89. 89Block modelling AdvantagesAdvantages
    • A block model can be used to test ergonomic properties which cannot be done on CAD models
    • A block model can be shown to/tested by potential customers to gain feedback
    • Block models can be made much more cheaply than producing the final product
    • A 3d block model allows the scale/proportions of the product to be evaluated so that it can be evaluated within its intended environment/use all design features have been considered and are correct/altered before costly production starts.
  90. 90Rapid prototyping using CAM/CADrapid prototyping (RPT). This involves the creation of 3D objects using laser technology to solidify liquid plastic polymers, or resins, in a process called stereolithography. Using specialist software applications on a stereolithography machine, 2D CAD drawings are converted to 3D models.
    The process is based on the computer slicing the 3D image into hundreds of very thin layers
    and transferring the data from each layer to the laser.
  91. 91Rapid prototyping using CAM/CAD 2The laser draws the first layer of the shape on to the surface of the resin, which causes it to solidify. The layer is supported on a platform that moves down, enabling the next layer to be drawn. This process of drawing, solidifying and moving down quickly builds up one layer on top of another until the final 3D object is achieved.
  92. 92Rapid prototyping Advantages• Saves time and money
    • Client able to see the product throughout the design process
    • Changes can be quickly incorporated
    • RPT can be done extremely quickly compared to traditional methods (1) therefore saving lead time/money (1)
    • RPT models can be made extremely accurately without the need for highly skilled craftsmen
    • RPT models can be made as hollow formings due to tool-less technology (1)
    • RPT models can be made with intricate detail allowing more realistic prototypes to be produced
  93. 93Rapid prototyping DisadvantagesDisadvantages
    • Because a rapid prototype is not the real product there is a danger that elements of the design can be missed
    Applications
    • Concept modelling
    • Solid 3D models
    • Architectural models
  94. 94CNC (Computer Numerical Control)• Fast method of production
    • Can cut complex profiles.
    • The machine works very accurately.
    • High level of repetitive accuracy achieved / no human error / less waste.
    • Minimal labour needed / minimal labour costs.
    • Safe method of production.
    • Shape is easily programmed
    • Data is easily saved / retrieved for future batches.
  95. 95CAMComputer-aided manufacture (CAM) is a process that converts drawings that have been produced using a CAD system into actual products. CAM can involve a range of machines, but the most common are lathes, routers, millinq machines and laser cutters.
  96. 96CAM 2There are many advantages to CAM. The cost of setting up CAM systems can be high, but once the initial costs are made and the system is programmed the advantages are considerable. The machines are able to work 24 hour a day with little human intervention. They ensure that the products they produce are consistently accurate. They are reliable and, because they can be reprogrammed, are very flexible.
  97. 97LathesMaterials cut
    • Metals
    Applications
    • Produce accurate and complex shapes that would be difficult to produce on hand operated lathes
  98. 98RoutersMaterials cut
    • Wood
    • Foam
    Applications
    • Similar to milling machine but using softer materials
    • Used for block modelling
    • Can cut 2D and 3D shapes
  99. 99Milling machinesMaterials cut
    • Metals
    Applications
    • Produce flat and complex curved shapes
    • In industry work to fine tolerances
  100. 100Laser cuttersMaterials cut
    PlasticWoodCard
    Applications
    • Cuts with intense beam of light
    • Material does not require clamping
    • Can cut both simple and complex shapes
    • Can cut faster
    • Can cut with a higher level of accuracy / less human error
    • Repetitive accuracy.
    • Laser can run 24/7 with minimal labour.
    • Material is less likely to break as there are no cutting forces.
    • Safer as laser is fully enclosed.
    • Tooling does not need changing /become blunt.
  101. 101QualityQuality refers to a product's ability to satisfy a need and, more importantly, its fitness-for-purpose. in manufacturing terms it is producing a product that is the best it can be. That is, fully functional and free from defects.
  102. 102Quality Assurance• Having systems in place to assure quality/ customer satisfaction in which cost and quality are in ‘harmony’ products are designed and produced to a standard / consumer guarantees.
  103. 103Quality Assurance Systems• Systems to check the design and development of the product.
    • Destructive and non-destructive testing / works effectively/ meets specification.
    • Systems to check raw material quality.
    • Sample testing / material reach expected standard /not substandard.
    • Systems to check the manufacturing processes / quality control.
    • Checking the size/ finish/ function so ensuring components/ products are manufactured to the required standard.
    • Customer support department to check customer satisfaction
    • Deals with customer feedback/ faulty products / honour guarantees
  104. 104Quality controlQuality control (QC) is the part of quality assurance that involves inspection and testing of a product, during or immediately after production.
  105. 105InspectionInspection is used to check that manufactured products have been produced within a specified tolerance. Tolerance is defined as the acceptable amount by which a product's size can differ from that stated in the specification.
    There are three main levels of inspection.
    • 100 per cent inspection: where all the units in the lot, or batch, are inspected.
    • Normal inspection: using a sampling plan.
    • Reduced inspection: using a sampling plan requiring smaller sample sizes than those used in normal inspection.
  106. 106Inspection 2Computer-aided inspection is possible by using a coordinate- measuring machine (CMM) for dimensional measuring.
    Laser scanning systems are often used that can determine the coordinates of many thousands of points. This data can then be taken and used to not only check size and position, but also to create a 3D model of the part using a CAD system.
  107. 107Positives of QC6. High quality / more reliable products produced.
    7. Good reputation/quality marks gained (BSI, ISO4000, etc).
    8. Leading to increased profits /higher value product / increased sales / money saved.
    9. Less returned products/ replacement products supplied.
    10.Sampling / computer driven /automated monitoring systems are cheaper to run.
    11.Increased QC checks will reduce the waste incurred when faulty goods are further processed/ faulty goods are disposed of / leads to increased productivity.
  108. 108Negatives of QCNegatives
    1. Running QC systems costs extra money /reduces profits.
    2. Increases selling price / price themselves out of the market / competitor products are cheaper.
    3. Set up costs eg. Equipment / training costs.
    4. Running costs eg. Labour/ energy /maintenance/ destructive testing/ etc.
    5. Slower production rate / time consuming / time needed to check every component / less products manufactured / sold.
  109. 109TestingTesting is concerned with the product's performance. Tests are carried out under laboratory conditions using strict control procedures to ensure that the results obtained are accurate.
    There are two main types of tests.
    • Non-destructive testing (or failure testing): where the product is tested until it shows signs of failing, for example cracking, to determine how much force is needed to deform it.
    • Destructive testing: where the product is destroyed under controlled conditions and monitored to gather valuable research data
  110. 110Total quality management (TQM)Total quality management (TQM), often referred to as total quality control (TQC), is the strategic integrated system for achieving customer satisfaction by applying QA procedures at every stage of the production process.
  111. 111Total quality management (TQM) 2TQM is based on all members of an organisation participating in the continual improvement of processes, products, services and the overall culture in which they work. Each department in a company is treated as a client, therefore ensuring high standards of service and attention to detail when dealing between departments.
  112. 112TQM Question Answer• TQM is how manufacturers implement quality assurance/quality control systems
    • For the continuing development/improvement of the product/process
    • For the complete life cycle of the product
    • Employee involvement/teamwork/work ethos/satisfaction
    • Customer focused involvement/feedback
    • Departments are treated like individual clients which leads to good relationships/good quality products
    • Quality assurance/Quality control test procedures happen at every stage of production
    • ISO 9000 is awarded for companies who demonstrate high standards of consistency/quality which leads to a good reputation/repeat business
    • System to achieve customer satisfaction / confidence by using Quality assurance
  113. 113TQM Advantages• ISO 9000 approved companies only buy components/materials from other approved suppliers
    • gives control over raw materials
    • Gives a record at every stage to aid product/process improvement
    • reduces waste / increases efficiency
    • improves customer satisfaction / feedback
    • quality is monitored at every stage
    • Enables products to be made ‘right first time’
    • It means the company’s reputation remains high
    • It often leads to repeat orders
    • It ensures that identical products are manufactured on time
    • TQM helps to deliver on budget
    • TQM helps to develop a team mentality
    • TQM facilitates ongoing product improvement
  114. 114Disadvantages of TQM• Additional costs of developing new ways of working. (1)
    • Additional costs of training staff. (1)
    • On-going costs of responding to workforce proposals. (1)
    • Benefits will take time to filter through. (1)
    • Some staff may be reluctant to embrace change.
  115. 115BSI ISO9000 StandardsThe British Standards Institute (BSI) operates a quality management system to which any organisation can be accredited. This system, known as the ISO 9000 series of standards, recognises companies who can demonstrate high standards of consistency in all of their procedures. The ISO
    9000 series is the world's most established quality framework and is used by over 250,000 organisations in 161 countries If an organisation is accredited with this standard, the customer is assured of the quality of the product and service.
  116. 116Benefits to Customers and UsersBenefits
    • Receive products that conform to the requirements
    • Are dependable and reliable
    • Are available when needed
    • Easily maintained
  117. 117Benefits to People in the organisationBenefits
    • Better working conditions
    • Increased job satisfaction
    • Improved health and safety
    • Improved morale
  118. 118Benefits to Owners and investors• Increased return on investment
    • Improved operational results
    • Increased market share
    • Increased profits
  119. 119Benefits to SocietyBenefits
    • Fulfilment of legal and regulatory requirements
    • Improved health and safety
    • Reduced environmental impact
    • Increased security
  120. 120Quality StandardsNational Standards, for example British Standards (suffix BS), are produced by a country’s national standards body (NSB). In the UK, British Standards (BS) are developed together with the UK Government, businesses and society.
    • European Standards (suffix EN) are produced by the European Committee for Standardisation (CEN), whose members are the NSBs of the European Union countries. In the UK, they are adopted as British Standards.
    International Standards (suffix ISO) are produced by the International Organisation for Standardisation (ISO), whose members are the NSBs of countries all over the world.
  121. 121Role of ISOThe role of the ISO is to
    • Define /set standards for products and processes worldwide.
    • Promote quality and safety in procedures /products by testing and certificating.
    • Promote product /system compatibility.
    • Encourage / facilitate international trade.
  122. 122KitemarkHaving a Kitemark® associated with a product or service certifies that it complies with particular standards. It means that any product or service that displays a Kitemark® has been through a number of rigorous quality processes and that consumers can buy products or services knowing that they have reached required standards.
  123. 123Kitemark logoKitemark logo
  124. 124CE MarkCE mark tells you
    • Product must meet / be tested against the relevant European directives.
    Is purpose is to establish / maintain a common standard of goods being traded across Europe which prevents poor quality / dangerous goods being imported / exported.
    To ease trade restrictions / encourage trade between European countries by eliminating the need for a product to comply with each individual countries own quality standards.
  125. 125CE Mark logoCE Mark logo
  126. 126Health and Safety at Work Act [1974]Under this Act of Parliament, employers are legally required to do all that is reasonably practicable to ensure the health, safety and welfare at work of employees, and the health and safety of non-employees such as students and visitors to a school. The following regulations are procedures to safeguard the risk of injury to people.
  127. 127PPE 1Personal Protective Equipment at Work regulations (1992) state that employers have basic duties concerning the provision and use of personal protective equipment (PPE) at work. PPE is defined in the regulations as ‘all equipment (including clothing providing protection against the weather) which is intended to be worn or held by a person at work and which protects him against one or rnore risks to his health or safety’.
    These can include safety helmets, gloves, eye protection, high-visibility clothing, safety footwear and face masks or respirators.
    The main requirement of the regulations is that PPE is to be supplied and used at work wherever there are risks to health and safety that cannot be adequately controlled in other ways
  128. 128PPE 2The regulations also require that PPE is properly assessed before use to ensure it is suitable, is maintained and stored properly, is provided with instructions on how to use it safely and used correctly by employees.
  129. 129PPE 3PPE 3
  130. 130The Safety Signs (Signs and Signals) regulations (1996)The Safety Signs (Signs and Signals) regulations (1996) require employers to display an appropriate safety sign and instruction wherever a significant risk or harm cannot be avoided or reduced by other means. These regulations bring into force a European Directive whose purpose is to encourage the standardisation of safety signs throughout Europe so that safety signs, wherever they are seen, have the same meaning.
  131. 131SignsSigns
  132. 132Health and Safety Executive risk assessmentsThe Health and Safety Executive (HSE) lays down government guidelines for health and safety issues within the workplace, including schools. The HSE states that all places of work must carry out risk assessments of their facilities to identity any potential hazards to employees or students, and to put in place control measures to reduce the risk of injury.
  133. 133Five Steps to Risk Assessment1. Identify the hazard.
    2. Identify the people at risk.
    3. Evaluate the risks.
    4. Decide upon suitable control measures
    5. Record risk assessment.
    6. Set a review date
  134. 134Why should risk assessments be recorded?• For training so that all risks and safe procedures are covered
    • Provides evidence that H&S legislation has been applied if accident occurs / HSE inspect / required in court
    • Provides a basis for review so that any changes can be built upon existing good practice
  135. 135Risks using Computers• The environment must provide adequate lighting and the heat produced by equipment must not cause discomfort to the user
    • The chair must be stable and allow for freedom of movement.
    The height of the chair and the backrest must be fully adjustable
    • The workstation must provide sufficient space for the user to change position and vary movements
    • The screen must swivel and tilt easily.
    Glare from the screen should be easily adjusted using brightness and contrast controls
    An anti-glare screen could be fitted
    • The keyboard should be able to tilt to provide a comfortable typing position
  136. 136Repetitive strain injuryRepetitive strain injury (RSI) is a medical condition affecting muscles, tendons and nerves in the arms and upper back.
    It occurs when muscles in these areas are kept tense for very long periods of time, due to poor posture and/or repetitive motions
  137. 137Eye Strain Prevention• Adjust glare from monitor using brightness and contrast controls
    • Use of an anti-glare screen fitted to monitor to reduce screen flicker
    • Tilt or swivel monitor to reduce reflections
    • Take regular breaks to rest eyes
  138. 138Workshop practicesWhen undertaking practical work in the workshop it is likely that you will be given the opportunity to work on a range of tools and machines. Obviously, there will be a wide range of potential hazards when using machinery, power tools and equipment. The school, or college, will have carried out a detailed risk assessment for each piece of equipment, which should be clearly displayed for your information.
  139. 139The Control of Substances Hazardous to Health (COSHHThe Control of Substances Hazardous to Health (COSHH) regulations place a duty on employers to make an assessment of risks for work involving exposure to substances hazardous to health. Steps must be taken to prevent or control adequately the exposure of employees and others to these substances.
  140. 140COSHH regulationsRegulations cover
    • Wearing PPE
    • Maximum safe exposure / controlling exposure e.g. extraction
    • Maintenance of protective equipment.
    • Training in safe working / handling of hazardous materials.
    • Frequency of monitoring / surveillance exercises.
    • Safe methods of storing the materials.
    • First aid measures in the event of accident /exposure.
    • Safe methods of disposing of waste.
    • Essential signage required.
  141. 141Hazardous SubstancesHazardous substances include:
    • substances used directly in work activities such as adhesives, paints and cleaning agents
    • substances generated during work activities such as fumes from soldering and welding
    • naturally occurring substances such as dust
    • Biological agents such as bacteria and other micro- organisms.
  142. 142Steps to ensuring COSHH regulations are met 11. Assess the risks
    Do not carry out work that could expose employees to hazardous substances without first considering
    2. Decide what precautions are needed
    Do not carry out work that could expose employees to hazardous substances without first considering the risks and the necessary precautions, and what else is needed to comply with COSHH.
    3. Prevent or adequately control exposure
    Prevent employees being exposed to hazardous substances. Where preventing exposure is not reasonably practicable, then it must be adequately controlled.
    4. Ensure that control measures are used and maintained
    Ensure that control measures are used and maintained properly and that safety procedures are followed.
  143. 143Steps to ensuring COSHH regulations are met 25. Monitor exposure
    Monitor the exposure of employees to hazardous substances, if necessary
    6. Carry out appropriate health surveillance
    Carry out appropriate health surveillance where assessment has shown it necessary or where COSHH sets specific requirements.
    7. Prepare plans and procedures to deal with accidents, incidents and emergencies
    Prepare plans and procedures to deal with accidents, incidents and emergencies involving hazardous substances, where necessary.
    8. Ensure employees are properly informed, trained and supervised
    Provide employees with suitable and sufficient information; instruction and training.
  144. 144Adhesives VOC riskMany adhesives are solvent-based, containing volatile organic compounds (VOCs) that give off vapours that can cause dizziness and nausea. Because of this, these substances are extremely hazardous to use within confined indoor areas such as workshops or classrooms. It is important that thorough risk assessments are carried out and the appropriate action taken to minimise the risks.
  145. 145Burns from corrosive adhesives• Use appropriate PPE, including gloves and eye protection
    • Users fully briefed on safe use of adhesives
    • Appropriate supervision by teacher or technician
    • Wash area immediately with warm soapy water and seek medical attention
    • Eyes: seek medical attention immediately; use an eye bath to wash eyes
  146. 146Inhalation of VOC vapours• Use only in well-ventilated areas, i.e. use extraction or open external windows/doors
    • Appropriate supervision by teacher or technician
    • Use of face-mask or respirator
    • If dizziness and nausea occur vacate area immediately and seek medical attention
  147. 147Storage of adhesives• Store in a secure metal cupboard
    • Cupboard easily identifiable (yellow) with appropriate safety signage clearly displayed
    • Staff to be fully briefed as to safe storage of adhesives
    • Checks by technician on a regular basis
  148. 148QuestionsGive, state
    These types of questions will usually appear at the beginning of the paper, or question part, and are designed to ease you into the question with a simple statement or short phrase. 1 mk
    Describe, Outline
    These types of questions are quite straightforward. They ask you to simply describe something in detail. Some questions may also ask you to use notes and sketches; you can gain marks with the use of a clearly labelled sketch. 2+ mks
    Explain, Justify
    These types of questions will be commonplace in this exam. They are asking you to respond in detail to the question - no short phrases will be acceptable here. Instead, you will have to make a valid point and justify it. 2+ mks
    Evaluate
    These types of questions will appear towards the end of the paper and are designed to stretch and challenge the more able student. They are awarded the most marks because they require you to make a well-balanced argument, usually involving both advantages and disadvantages 4+ mks

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Flashcards on AS DT Revision 2, created by Aidan Magee on 22/05/2016.
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