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Flashcards in Novel processing techniques Deck (11)
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1

Describe friction stir welding

The joining of materials without the need for filler materials

2

List advantages and disadvantages of friction stir welding

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

What is the advantage of powder metallurgy processes over casting

PMP have a very low scrap rate compared to casting processes

4

List advantages of additive layer manufacturing

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

5

Powder metallurgy processes - laser system

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

6

Powder metallurgy processes - Electron beam

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

Disadvantages to additive layer manufacturing

- its expensive
- certain powders are expensive
- cannot have every material in powder form
- highly skilled workers needed

8

Describe metal injection moulding

1. Start with powder
2. Add Binder and heat
4. form granules and inject into mould
5. remove Binder
6. Sinter

9

Why is sintering needed in metal injection moulding

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

10

General equation for mechanical effects of porosity

X = Xo * e^(βρ)

11

Describe hot isostatic pressing (HIP)

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