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Materials and Manufacturing > Manufacturing > Flashcards

Manufacturing Flashcards

1
Q

Subtractive processes examples

A

Machining and grinding (energy put in by machine to remove material)

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2
Q

Formative processes (deforming) examples

A

Casting and forming (energy put in to re-shape)

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3
Q

Additive processes examples

A

Joining and 3D printing (energy put in to add material)

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4
Q

Machining (subtractive process) examples

A
  • Milling
  • Turning
  • Broaching
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5
Q

Machining characteristics

A
  • Grinding has higher precision compare to milling and turning (machining processes).
  • tools and workpieces can be fixed or moving. (But one has to move to remove material)
  • tools can be single point, multi point or abrasive wheels.
  • Feed can be transverse (work done in perpendicular direction the the directing the workpiece is facing) or longitudinal
  • reciprocates movement is when you move back and forward.
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6
Q

Turning processes (done on a lathe)

A
  • Turning: process of removing material from the outer diameter
  • facing: process of removing metal from the end/face of the workpiece creates flat end surface
  • Parting off: cuts workpiece to a specified length (transverse feed)
  • Thread cutting: creates threads by cutting helical ridge (CNC)
  • Boring: holes created to remove internal material
  • Knurling: creates a textured surface
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7
Q

Work holding in a lathe

A

•3 jaw ‘self centring’ chuck:

  • all jaws move at same time
  • low accuracy

•4 jaw ‘independent’ chuck:
- all jaws move independently
- allows workpiece to be manually aligned
hence accommodates more complex shapes

•Collect chuck:

  • precision made high accuracy
  • only accommodates specific size workpiece
  • allows accurate transfer between two processes as mounts component centrally on its axis.
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8
Q

Machining sequence

A

Set true gauge used to ensure material is correctly mounted and central to rotating axis.

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9
Q

Milling (machining process) uses:

A
  • surface cutting curved

* gear cutting

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10
Q

Milling machines

A

•vertical milling machine:
-tools gripped at one end

•horizontal milling machine:

  • larger cuts possible
  • tools supported at both ends
  • more robust design
  • less flexible than vertical milling
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11
Q

Forming vs generating

A

Forming: shape cutting tool used to create shape of final component

Generating: final component shape is created by moving cutting tool along a path

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12
Q

Cutting method

A
  • Up cutting: tools need to be sharper as more force needed
  • down cutting:
  • good surface finish
  • less power consumed
  • backlash major problem (requires clearance for movement or causes uncontrolled movement in a system which cause wear )
  • high rigidity required
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13
Q

Drilling (machining method)

A

•Two cutting edge (standard two fluted drill):

  • cutting forces balanced
  • low cost
  • efficient
  • poor heat removal and accuracy

•reamer
-improves accuracy and surface finish as removes a small amount of material

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14
Q

Broaching (machining process)

A
  • Used to produce special shaped holes and slots
  • fast and low cost operation
  • operates like a saw blade successive teeth remove material
  • excellent repeatability
  • tools high cost
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15
Q

Thread cutting (tap and die)

A
  • internal threads cut using taps

- external threads cut using circular split dies and solid but dies. For capstan use Coventry die head

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16
Q

Casting (formative process) metals

A

Process in which a material in liquid form is poured into a mould and allowed to become hard, in order to make parts.

17
Q

Casting advantages and disadvantages

A

•Advantages:

  • production of final shape in a single step
  • complex shapes
  • low component cost

•disadvantages:

  • rough surface finish
  • poor dimension accuracy from shrinkage
  • low strength
  • high setup and energy costs
18
Q

Sand casting

A

Sand is the mould material you pour the hot liquid material for example metal into (example engine block cavities surrounding the cylinders)

  • strong but not reusable
  • withstands high temps (refractoriness)
  • bonds together (cohesiveness)
  • permeability allows mould to breath
  • collapsibility-breaks up easily after cooling
  • availability
19
Q

Shell moulding (casting method)

A

mold casting process that uses a resin covered sand to form the mold. As compared to sand casting, this process has better dimensional accuracy (no shrinkage), a higher productivity rate, and better finish.

Disadvantages- high cost and can have visible parting line

20
Q

Casting finishing operation

A
  • cleaning- removing mould and repair minor defects: wielding
  • heat treatment- 1000 degrees many hours controlled cooling (homogenisation)
  • inspection- x Ray, dye penetration and magnetic particle testing
21
Q

Joining (additive process)

A

Assembly of parts
•engineering systems conplex eg car 15000 parts
•assembly accounts for 50% of manufacturing costs
•easier maintenance as parts can be disassembled and replaced
•allows mass production and reduces cost

22
Q

Methods of joining

A
  • Mechanical joining: bolt, nut, screw etc
  • Brazing/soldering: low melting point filter
  • wielding: act of joining together two or more components by heating the parent metal surfaces and a solid connection with or without the use of a filler metal.
  • adhesive bonding: polymer adhesive
23
Q

Metal forming process (formative process)

A

•Hot forging-involves hammering
•Hot rolling-where the material is passed through a pair of rollers
•Cold rolling-
•extrusion
•Rod, tube & wire drawing
(Better surface and tolerance than casting but worse than machining)

24
Q

Electro discharge machining (EDM) subtractive process

A

manufacturing process whereby a desired shape is obtained by using electrical discharges (sparks). Material is removed from the work piece by a series of rapidly recurring current discharges between two electrodes, separated by a dielectric liquid and subject to an electric voltage. separated by a gap small enough for electrical discharge

Higher energy, higher material removal rate and tougher surface

25
Q

3 uses of EDM

A
  • Die sinking EDM- slow process (expensive) but produces high quality surfaces. Main applications moulds for injection moulding
  • Wire EDM- only works with electrically conductive materials. Only produces 2D shapes. Advantages high quality surfaces
  • EDM drilling/milling- but can produce deep holes. Milling time consuming but can produce accurately complex 3D shapes used for small cavity.
26
Q

Laser processing (subtractive)

A

a form of machining, in which a laser is directed towards the work piece for machining. This process uses thermal energy to remove material from metallic or nonmetallic surfaces. The high frequency of monochromatic light will fall on the surface then heating, melting and vaporizing of the material take place due to impinge of photons. Laser beam machining is best suited for brittle materials with low conductivity, but can be used on most materials.

27
Q

Water jet and chemical machining (subtractive)

A

Water Jet Machining (WJM) is a mechanical energy based non-traditional machining process used to cut and machine soft and non-metallic materials.

Water jet machining is used to cut thin non-metallic sheets.
It is used to cut rubber, wood, ceramics and many other soft materials.
It is used for machining circuit boards.
It is used in food industry

28
Q

Injection moulding (formative process) plastics

A

process for producing parts by injecting molten material into a mould, or mold. Injection moulding can be performed with a host of materials mainly including metals (for which the process is called die-casting), glasses, elastomers, confections, and most commonly thermoplastic and thermosetting polymers.

it is ideal for producing high volumes of the same objects. wire spools, packaging, bottle caps, automotive parts and components, toys, pocket combs, some musical instruments (and parts of them), one-piece chairs and small tables, storage containers, mechanical parts (including gears), and most other plastic products available today.

29
Q

Micro-electro-mechanical systems (MEMS)

Additive process

A

Integrated circuits technology and micro chips

Materials and Manufacturing (2 decks)

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