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Flashcards in Novel processing techniques Deck (11)
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1
Q

Describe friction stir welding

A

The joining of materials without the need for filler materials

2
Q

List advantages and disadvantages of friction stir welding

A

A:

  • excellent mechanical properties
  • no porosity or distortion
  • non consumable tool
  • can perform on the spot repair work
  • can work at high temperatures

D:

  • costly equipment
  • same materials are hard to FSW
3
Q

What is the advantage of powder metallurgy processes over casting

A

PMP have a very low scrap rate compared to casting processes

4
Q

List advantages of additive layer manufacturing

A
  1. Design friendly
  2. Low lead times
  3. Reduces buy-to-fly ratio
  4. Near-net shape products
5
Q

Powder metallurgy processes - laser system

A

applies heat only the part slice, therefore don’t get uniform heating. This leads to residual stresses.
Impossible to do thin walls.

6
Q

Powder metallurgy processes - Electron beam

A

Most promising technology. Uses Ti-6Al-4V and CoCr.
Preheats every layer so properties are very good.
Have to build supports, but these are recyclable.
Must be very careful with parameters.
Need skilled workers

7
Q

Disadvantages to additive layer manufacturing

A
  • its expensive
  • certain powders are expensive
  • cannot have every material in powder form
  • highly skilled workers needed
8
Q

Describe metal injection moulding

A
  1. Start with powder
  2. Add Binder and heat
  3. form granules and inject into mould
  4. remove Binder
  5. Sinter
9
Q

Why is sintering needed in metal injection moulding

A

After debinding, the material is very brittle and only 70% dense.
Sintering compacts product and makes it 100%

10
Q

General equation for mechanical effects of porosity

A

X = Xo * e^(βρ)

11
Q

Describe hot isostatic pressing (HIP)

A

Simply: put powder in chamber and squeeze creating 100% dense product and eliminating porosity