ENGI1002 - Topic 9

What is casting?

Molten metal is poured into a mould. Upon cooling, the metal solidifies and takes on the desired shape.

What is rolling?

Materials squeezed together between two rollers, thinning and lengthening the material.

What is drawing?

Drawing creates cup-shaped parts by forcing sheet metal into a die.

What is metal extrusion?

Produces a cross-sectional shape using soft alloys such as aluminium.

What is forging?

A hammering process undertaken at high temperatures.

What is annealing?

Annealing restores a cold-worked metal to a soft and malleable condition.

What are the stages of annealing?

• Recovery

• Recrystallisation

• Grain growth

What is transfer moulding used for?

Transfer moulding is used for thermoplastics and thermosets.

What is injection moulding used for?

Injection moulding is used for thermoplastics.

What does extrusion for polymers produce?

Extrusion for polymers produces long products.

What does blow moulding produce?

Blow moulding produces hollow plastic products.

What does melt spinning produce?

Melt spinning is an extrusion-type process that produces polymer fibres.

What is glass pressing?

Glass pressing involves forming glass into the shape of a mould using a ram.

What is glass blowing?

Glass blowing involves using compressed air to force softened glass into the shape of a mould.

What does annealing glass do?

Annealing glass removes internal stress.

What does tempering do?

Tempering puts surface of glass part into compression, suppressing surface crack propagation.

What are clay products made of?

• 50% clay

• 25% filler (quartz)

• 25% flux

What happens when water is added to clay?

Clay becomes plastic when water is added. This allows materials to shear easily along weak Van der Waals bonds.

What does drying clay due?

Drying clay causes it to shrink.

What does firing clay do?

Firing clay reduces porosity.

What is clay extrusion for?

Clay extrusion to make products such as bricks.

What is slip casting for?

Slip casting to make hollow or solid items.

What are the types of powder pressing?

• Uniaxial compression

• Isostatic compression

• Hot pressing

What is uniaxial compression?

Compacted in a single direction.

What is isostatic compression?

Pressure applied by fluid.

What is hot pressing?

Heat + pressure

What is sintering?

Sintering densifies and strengthens powder parts. It is driven by reduction in surface area.

What are the 7 categories of 3D printing?

1. Binder jetting (BJT)

2. Directed energy deposition (DED)

3. Material extrusion (MEX)

4. Material jetting (MJT)

5. Powder bed fusion (PBF)

6. Sheet lamination (SHL)

7. Vat photopolymerisation (VPP)

Advantages of 3D printing?

• Rapid prototyping

• Quick turnaround time

• Faster design improvements

3D printing workflow?

1. CAD design

2. Slicing

3. Print

4. Post processing