Flashcards in Moulding and Joining Deck (18):
How does vacuum forming work? (5)
1. A mould is put onto the vacuum bed
2. Thermoforming plastic sheets are clamped above the vacuum bed until they go soft.
3. The vacuum bed is lifted close to the heated plastic.
4. The air is sucked out from under the plastic, creating a vacuum. The air pressure from outside the mould then forces the plastic onto the mould.
5. The moulded plastic is cooled and the vacuum bed lowered. The cold plastic is rigid so holds its new shape.
How does blow moulding work? (2)
1. A tube of softened plastic is inserted into a solid mould.
2. Air is then injected which forced the plastic to expand to the shape of the mould.
What plastics are used in vacuum forming?
Hips or polypropylene.
What are vacuum forming moulds made from?
What products are produced using blow moulding?
Bottles and containers.
How does injection moulding work?
How does extrusion work? (2)
1. The material is melted and forced under pressure, through a die.
2. This produced long, continous strips of moulding exactly the same shape as the exit hole.
How does drape forming work? (3)
1. A sheet of thermoforming plastic is heated until it softens.
2. The softened sheet takes the shape of the mould that it is placed on.
3. Once the plastic has cooled it will stay that shape.
Describe the uses of Polyvinyl acetate (PVA)
Can bond wood, paper and card. It dries slowly and has a curing time of about 24 hours.
Describe the uses of glue guns
Melted plastic is used to join woods and fabrics. Very good for modelling.
Describe the uses of solvent cement
It can join some plastics and the joint must be clamped while it sets.
Describe the uses of epoxy resin or superglue
They can be used on most materials and set quickly. Quite expensive.
What is soldering?
A low temperature process that involves melting solder onto components to be joined. This sticks them together when it cools and solidifies. For metals
What is brazing?
A high temperature process that uses brass-spelter to join metals. It is much stronger than soldering.
What is welding?
A very strong and high temperature process that melts the edges of a joint so that they can flow together.
What is solder made from?
Tin and other materials
What is spot welding?
Where metal sheets are melted and joined at a number of separate spots along their edge. This type of weld doesn't require welding rods, and is often carried out by robots on production lines.