METAL PROCESSES

Question 1

Explain the process of die casting

Answer 1

Uses hot and cold chamber
Hot die casting
= when metal is heated within the a chamber and poured into the die.
- Similar to polymer injection moulding
- When product has cooled, ejector pins remove item from mould

Cold chamber
=die casting is the same however the metal is heated elsewhere

Question 2

Explain the process of gravity casting

Answer 2

Molten metal is poured into the mould, then is distributed into the die from the gravitational force
- (the air within the die can escape as the metal is poured into the mould)
- cost effective as doesn’t require complex and large machinery
- very small intricate parts cannot be produced because molten metal can’t get into the tiny gaps
- has no wastage

Question 3

Explain the process of press forming

Answer 3

Is a process where a pressing force is applied to a material, such as bending so that it matches the size and shape of the die
- also called cold forming as metal is not heated
- mould is used over and over again

Question 4

Explain the process of deep drawing

Answer 4

Process of converting sheets of metal into a cylindrical container with a flat base
- the sheet of metal is placed on a die
- the metal is then clamped to the die
- a punch pushes down onto the sheet of metal using a hydraulic press

causes metal to take the form of the dice
cannot create intricate parts

Question 5

Explain the process of sintering

Answer 5

Process of compacting and forming a solid mass of material by pressure or heat without it melting to a liquid
- results in a harder, stronger, more durable, mass due to the high heat and pressure
- formed by intense pressure, molecules and atoms become very close, then as the particles are heated the molecules expand and form together

Question 6

Explain the process of forging

Answer 6

Shaping of a material using localised compressive forces
- the metal is hit with a hammer or die or rolled to change the shape
- can have hot or cold forging

Question 7

Explain the process of pressure die casting

Answer 7

This process forces molten metal at high speeds and high pressure into a closed steel die cavity.
The die has a stationary and a moving half, both of which are mounted to the die casting machine platens.
The die casting machine has an injection end that uses hydraulics and pressurised gas to move a plunger forward.
This forces the metal to fill the die cavity, which is then held shut using hydraulics allowing the metal to cool and harden.
The entire process can be completed in a matter of seconds.

Question 8

Explain the process of investment casting

Answer 8

Also known as lost wax casting is a precision metal casting process as it can make high accuracy and intricately detailed castings.
- In investment casting, a wax is coated by dipping into ceramic material slurry.
-Once the ceramic material coating has hardened then the dipping process is repeated multiple times to increase the coatings thickness and strength.
- After the final coating is hardened the wax is melted and molten is poured into the cavity created by the wax.
- When the metal has solidified the casting is removed, therefore breaking the ceramic structure.

Mould is only used once

Question 9

Explain the process of sand casting

Answer 9

• Sand is compressed around a die then the sand is split in half so the mould can be removed, the molten metal is then poured into the cavity in the sand
• Not always very accurate or reliable
• Time consuming
• Creates a lot of wastage however wastage can be re-cast
• Very simplistic process
• Not good for mass production
• can be used in jewellery

Question 10

Explain the process of Metal spinning

Answer 10

Metal isn’t heated (lead is often used as it is already malleable)
- A metal sheet is placed on a lathe then pushed under intense pressure over a mould (mandrel), metal must be pushed slowly to allow it to take the shape of the mandrel;

• mould can be used consistently again and again
• low chance for error
• no excess material