Eng C9 1-30

• Metal stock


  Comes covered in grease to reduce oxidation and corrosion (rusting)
• Ferrous metals rust
• Issues with metal stock being covered in grease

  • It becomes slippery which could mean that it could become difficult to handle (potential hazards)
  • It could also make marking out incredibly difficult as the surface is uneven and unclean
• Cleaning metal stock


  1. Wire brush, wire wool - removes rust/corrosion

  2. Solvent- breaks down the grease

  3. Cloth- wipe clean
• Solvents


  • Dangerous chemical
  • Flammable- can catch fire, store in a heatproof locked cabinet
  • Irritant- skin must be covered with gloves and overalls
  • Harmful- make sure they do not enter your eyes or mouth
• Deburring


  Using a file to remove sharp edges, smooth finish from a rough cut
• Deburring must take place before marking out as this could cause injuries to the engineer
• Engineers blue


  Metals are difficult to mark out with pen or pencil. Engineers blue can be added which will dye the surface of the metal. This then makes marking out easier as the scratches can be seen more clearly
• Tolerance


  • Engineering tolerance is a value that tells engineers their "margin of error"
  • For an assembly made up of different parts to fit together, each one needs to be made the correct size. The symbol called the plus minus sign (+ or -), indicates how big or small the part must be to fit with the rest of the pieces
• Tolerance is good because it reduces waste as it gives a margin of error, for example house foundations will need to have a less precise tolerance compared to weighing scales which will need to be more precise
• Types of drill


  • Cordless drill- used on construction sites, use a battery not plugged in, light enough to carry around
  • Pillar drill- fixed machine to the floor, used on a range of materials, good for use on harder materials, space for bigger materials because of the space between the bed and drill bit
  • Bench drill- smaller distance from the bed to the drill bit, fixed to a bench
• Setting up a pillar drill

  1. Make sure your workpiece is clamped down with a G clamp or vice

  2. Make sure the drill bit is tightly fitted into the jacobs chuck, use the chuck key

  3. Check that the emergency stop button works

  4. Make sure the guard is down and covering the full drill bit

  5. Make sure the bed (table) is altered to the right height

  6. Make sure the drill bit is free from swarf (when drilling material can fill the grooves in the drill bit, make sure the drill bit is clean)
• Risks from drilling


  • Inhaling wood dust
  • Flying objects hitting eyes, head, hands, arms
  • Materials falling from the bed due to not being clamped properly
  • Hair/loose clothing becoming trapped
• Things an engineer must consider before using a saw

  • The condition of the saw: missing teeth and damaged guards
  • The shape of the cut (straight, curved, or intricate) shown on the engineering drawing
  • The material that can be cut (wood, metal, plastic)
  • The thickness/density of the material and the force required
  • The scale of production (how many cuts/products need to be made)
  • The location: in a workshop or on a work site
• If you don't choose the right saw, the saw could come broken, the cut won't be a nice clean cut and it could cause fire! Sparks = fire
• Difference between hand and power saws

  Hand saws are good for small, one off jobs. Power saws are good for larger jobs where you need to cut multiple pieces. You wouldn't want to cut out 400 pieces of steel by hand would you?
• Types of files


  • Flat files can be used to draw or cross file materials
  • Round and half round files are used to create internal curves
  • Square files create an inside corner that needs a right angle at 90°
  • Triangular files create tight corners that are less than 30°
• What happens to metal when it is bent

  • It becomes harder and stronger, and products have a smooth flowing form.. Think about cars for example. Metals are malleable, they can be shaped easily
  • It means when shape is added through force
• Bending wood


  By steam, known as 'steam bending'. The wood must be elastic though, such as oak and ash. They will use a jig and pins to set the shape
• Forming and shaping plastics


  1. Formed- injection moulding: pellets are melted and then formed into a mould, its then put into an oven which sets the shape

  2. Shaped- using a line bender/strip heater (whatever you want to call it). It will melt the plastic so it can then be shaped

  
• Metal casting


  Once you have extracted metals they must be formed into usable shapes and sizes to be sold. The metal is melted and formed into different shapes; this is called casting

  
• Types of casting


  • Die casting uses dies (moulds) made from tool steel, they take a long time and a lot of skill to produce but are useful when making tens of thousands of products or more
  • Investment casting requires a wax pattern made by a combination of machine and hand moulding. Wax is then coated in a ceramic shell, then the wax is melted away and a shell with many cavities is formed. Batches of identical parts are possible
  • Sand casting is best for smaller quantities of products, as packing sand around a pattern is time consuming

  
• Die casting


  • Uses aluminium because it has a low melting point, and flows quickly into the dies (moulds)
  • It is fast, accurate and parts don't need much finishing so parts can leave the factory quickly

  
• Finishing methods after casting

  • Drilling holes to ensure they are within tolerance
  • Milling flat surfaces to reduce size or improve the surface
  • Surface grinding to remove imperfections and pitting
  • Polishing to ensure the surface has a shiny finish and is clean
  • Spray painting/galvanising/anodising to protect from corrosion
• Die casting parts and uses

  • Dies(mould) – Made from a tool steel these have a cavity in the middle which will be filled and when opened, the final casting will be the correct shape
  • Chamber – This is a giant container that holds the molten metal
  • Cavity – The gap in the dies that is the shape of the final part where the liquid gets poured
  • Molten – Liquid metal
  • Alloy – A combination of two or more metals

  
• Risks with molten metal

  • Molten metal is metal that is heated so it turns into a liquid
  • It is unpredictable and can splash and cause burns
  • Risks to permanent damage to eyes- blindness
• Protection from molten metal

  1. Leather or suede apron and gaiters/spats that cover their steel toe cap shoes and thick cotton overalls covering their legs and arms

  2. A full-face visor and leather gauntlets (gloves) to protect parts of their body from burns
• Sand casting


  1. A wooden pattern is placed into a drag, which is upside down on a flat surface

  2. Casting sand is packed tightly around the pattern

  3. The drag is turned over, the cope placed on top and parting powder applied

  4. The second part of the pattern and sprue pins are added, sand packing continues

  5. The sand is tightly packed to prevent collapse; the cope is lifted off the drag and turned over

  6. The patterns and sprue pins are removed, the cope and drag are put back together, a cavity is left
• Problems with sand casting


  • very time consuming
  • dangerous
  • when the pins and patterns are removed, the sand could collapse and you just start again!
  • air bubbles can create weaknesses
  • if the sand is not stored in a dry place, or left to go out of date the casting can explode when the metal is poured
  • low strength compared to other casting methods
  • Final finish is poor, so requires finishing
  • Parts shrink, so the product can be inaccurate
• Advantages of sand casting

  • Any size/part can be created
  • most alloys can be sand casted
  • complicated parts can be made
  • moulds can be reused most of the time
• Sand casting parts and uses


  • Casting sand – A special oiled sand that is very fine and binds together
  • Sprue pin – A cone shaped wooden pin that creates a gap in sand that molten metal can be poured into
  • Runner – A gap that reaches a cavity, that molten metal is poured into
  • Riser – A gap that allows gas and excess metal to leave once the cavity is filled with metal
  • Pattern – The final shape of the part, usually made in wood, that sand is packed around
• Control measures for sand casting

  • Safety signage remind operators to be cautious, PPE available and always worn, staff to be aware of hot work area hazards
  • Strict policies around the failure to wear PPE, such as the rules around gross negligence to terminate employment immediately, if a member of staff is found to be unsafe
  • Regular training offered by an employer to staff involved in the process
  • Staff who are untrained are prohibited from entering dangerous areas of the workplace
  • Access to first aid equipment, including fire blankets and a suitably qualified first aider on site
  • No lone working in case of an emergency
  • Fire and explosion evacuation routes planned and practised by all employees
  • Access and training in the use of fire extinguishers
  • Foundry technicians to conduct and note handover at every shift change
  • Training in the use of natural gas
  • Gas manual and emergency cut off valves tested regularly
  • Routine maintenance performed on extraction systems
  • Work areas well ventilated, workers to take regular breaks
• Soldering


  • Uses molten metal to join gaps
  • Uses molten metal to connect pieces of metal
  • Join electrical components
• Types of soldering


  • Soft soldering - used on electrical components
  • Hard soldering- also known as brazing. Joins two pieces of metal together with a filler material. Such as connecting 2 copper pipes