Manufacturing Processes And Techniques 1 Flashcards
Why model?
For: Ergonomics Aesthetics Functionality Feasibility Proportions Scale/size Testing mechanisms and components
In long run it saves time, reduces manufacturing costs and avoids mistakes
Materials for modelling
- plastic
- styrofoam
- wood
- clay/plasticine
- paper/card
- metal wire
- polystyrene
- breadboard
2 modelling processes
- subtractive manufacturing process: making multiple components to assemble into the model by carving/sculpting
- CAD/CAM: for complex models
What are iterations
Repeats
processes of making
- fabrication
- additive
- casting
- subractive
- forming
- moulding
digital simulations
- designing products digitally
Advantages:
- design alterations are immediately visible
- product visible from all sides
- removes the need of physical prototypes
- new ideas can be tried quickly and changes can be visualised
- used to test circuits and mechanical devices: saving money and time and expensive parts
- stresses on individual components can be predicted and parts can be strengthened
Additive modelling processes and rapid prototyping
e. g. 3D printing
- allows designers to produce innovative designs that are complex to manufacture and can be produced at a fast pace
- different base materials: powder/liquid
- different processes: SLA(stereolithography), MJM (multi-jet modelling), SLS (selective laser sintering) and FDM (fused deposition modelling)
advantages:
- can program and build a part rapidly minimising cost and time
wasting/subtracting
removes or cuts away material to leave the desired shape
what is important while drilling
- drilling speeds are important
- larger the drill, slower the speed
- use a jig
kerf
width of the cut
must be wider than blade to avoid sticking
- avoided by setting teeth to left/right
snips/shears
- used to cut thin metal sheets/ soft polymers
types of saws
- back saws
- frame saws
- hand saws
- other
bandsaw / circular saw
- used by technicians or teachers
- to cut and prepare wood
- used in manufacturing industry
scroll / hegner
- fixed saw
- for intricate shapes on thin sheets
jig saw
- portable
- cuts curves
power hacksaws
- for bars of metal and polymers
examples of hand saws
- cross cut saw (used on large sections of wood when cutting across grain)
- panel saw (cutting panels in large sheets of wood)
- rip saws (cutting/ripping down grain on large sections of wood)
examples of back saws
- tenon saw (wood)
- dovetail saw (smaller for accurate works, back limits cut)
examples of frame saws
- coping saw (curves in thin sectioned wood)
- hacksaws (metal, fine blade)
- piercing saw (metal, finer blade used for jewellery)
Turning
- when the wood, plastic or metal is turned
- the material can be held using a faceplate or between the centres for slimmer items
- different lathes: wood working, centre, copy
- three jaw self-centring chuck, four jaw independent chuck
milling
- when the cutter is turned
- horizontal miller - the tool spindle axis is in the horizontal plane
- vertical miller - the tool spindle axis is in the vertical plane
- used to machine flat surfaces, slots and steps
- work table can be raised or lowered or moved horizontally
common cutting tools for milling
- slab cutters - for wide/flat surfaces
- slide and face cutters - have teeth all around the faces
- slotting cutters - thinner with only teeth on the periphery
- slitting saws - thinnest for narrow slots
Surform, riffler files
Surform - industrial cheese grater
Riffler files - for jewellers/ tool makers
what is an abrasive
it is any substance that wears down a surface by rubbing against it e.g. powders, papers, brushes, belts
how are grinders made
- made from abrasive grit e.g. aluminium oxide, bonded together
abrading facts
- polishing or buffing machines use abrasive compounds such as Tripoli applied to cloth mops
- Disc/angle grinder, surface or off-hand grinder for metals
- disc and belt sanders for wood
smoothing metals, plastics, woods
wood: glass paper
metals: emery cloth
Polymers: silicon carbide
Riveting
- joining flat sheet
different types: set and snap riveting, pop riveting - done with pop rivet gun
what are threaded inserts
a non permanent joint, those red things in the wall that dad uses
soldering
- involves two or more metal components that are joined together by melting and flowing a metal filler material into the joint
- the metal filler material has a lower melting point than the metal
- lead and tin alloy also lead free alternatives
- flux is used to clean surfaces and prevent oxidisation
- used for electrical connections e.g. circuit boards
Brazing
- similar to soldering with higher temperatures >450 c
- metal filler either an alloy of silver (silver soldering/brazing) or brass or bronze - based alloys
- gas torch is used to provide heat e.g. butane, propane, oxy-acetylene
welding
- the materials are joined by heat. The pieces are placed together, heated, with a filler material, brought to melting temperature and then left to cool
- essential that the materials to be joined and filler material are similar
- mild steel is one of the easiest to weld, stainless steel is worst
- while the metal is molten during welding it can absorb impurities from the atmosphere that will weaken the material once it solidifies so a flux e.g. oxygen should be used
types of welding
- friction welding using mechanical energy
- gas welding (mix of 02 and acetylene)
electricity is used in arc-welding e.g. MIG/TIG/spot welding
adhesion benefits
- provides discrete joints with little evidence of how it is secured
- reduces the need for mechanical joints therefore reducing manufacturing time, level of skill required and costs
- acts as a sealant
- it is permanent and will not fail or become loose under normal design loading if correctly made
adhesive facts
- it takes additional processing e.g. preparing surfaces, setting/curing. Adhesive tape can also be used to reduce setting time
- synthetic adhesives are sometimes stronger than the materials they are joining
- natural adhesives are non toxic
PVA facts
synthetic polymer, good on porous/semi-porous materials, pressure must be applied to the joint, drying time: 30-60 mins
Hot melt adhesive facts
e. g. glue gun, EVA
- fast curing, high strength joint, viscous at low temperatures
Polyurethane resin facts
e. g. super glue, epoxy resin (2 parted)
- joins dissimilar materials
silicon adhesives/sealants
flexible, high temperature resistance (-40 c - 1200 c), joint lacks strength
pressure - sensitive adhesive
e. g. PSAs
- adhesive tapes e.g. masking tape/sticky tape
solvent adhesives
- used on polymers, those containing styrene
- dissolve the surface of the materials into a semi-liquid state, the surfaces then flow together until the solvent evaporates, leaving the components permanently joined.
contact adhesives
applied to both surfaces and allowed to dry, then they are brought together and they bond rapidly, no clamps needed
Explain why CAE (computer aided engineering) software would be used in the development of an electronic system, such as in a microwave oven
- Simulation of the mechanical gear system using
modelled gears to examine performance. - Testing choice of materials in the gear
system/ exploring different materials and how they
differ in use. - Modelling the electronic system, creating a
testable circuit which can be tested at different points.
Explain ways in which new technologies could assist in the design and manufacture of a linkage component.
- A digitally designed linkage could be analysed with CAE software , to test material strength/flexing/durability etc.
- New material technology could be explored to improve the performance, considering the needs of this situation, e.g. strength/flexing/durability/water resistance, low friction.
- The linkage could be modelled through the use of 3D rapid prototyping, and this part could then be used in a digital model to test the movement of the mechanical system
- Once modelled through digital design the file could be sent for 3D printing or CNC machining, which would be a lost cost/high accuracy/fast method of producing the linkage part.
Explain why design engineers would consider the environmental impact during product manufacture
- The choice of whether to use raw resources to manufacture parts or use recycled or reused material. There is always an option to use recycled pellets in a
thermopolymer product the for instance – this option would not be available if a thermosetting polymer was chosen. - In order to minimise the amount of material used, the design engineer may consider the quantity of material used to manufacture parts, reducing quantities where possible. This will result in less material taken from their source, particularly when from a non-renewable source.
- the choice of a manufacturing system/company with a low carbon footprint and/or low pollutant emissions which might attract a financial bonus linked with an environmental incentive
- end of life considerations - designing the product to be manufactured in a way which makes it easily separable into component parts for recycling at the end of products life. This is attractive to stakeholders and may attract
financial incentives.
polymer moulding methods
- thermoforming (vacuum, drape and plug assisted) : a plastic sheet is melted and formed using a mould - polystyrene, polypropylene, PVC melted to 160-180 degrees
- to bend a straight lie a strip heater / line bender is used
- Pressforming (plug, yoke) : 2 part mould used to shape a heated sheet of polymer
The use of digital technology for prototypes
- CAD - design and test prototypes before manufacture
- CAM - translates the CAD part for manufacture
- CNC - machines used to produce prototypes e.g. laser cutter, 3D printing (computer numerical control)
- allows for high tolerances and repeated identical parts
- CNCs require ‘setting-up’ and adjusting before they can be used
CNC laser cutter
- cut and engrave thin sheet materials
- they burn and vaporise the material and must be focused
CNC plasma cutter
- uses an accelerated jet of hot, electrically conductive gas, known as plasma
- only cut electrically conductive materials that are thick
CNC router
- 2D cutting machine that engraves, drills holes and produces slots and steps (the big square machine in the corner)
CNC milling machine
- like router but got deep cuts from solid block (the old industrial machine behind the router in DT)
CNC lathe
- for producing cylindrical shapes (the machine the other group was using for making pens)
