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Design And Technology > As > Flashcards

As Flashcards

1
Q

What is the process of bonding timber together?

A

Lamination

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2
Q

How is lamination performed?

A

Wood veneers or thin MDF are glued together before being bent over a former.
As the glue dries the materials set in the former shape.
Clamps or a vacuum bag prevent any movement
Glue of choice is usually cascamite

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3
Q

How is using a vacuum bag in lamination beneficial and how does it work.

A

Prevents any gaps forming.
Veneers and former placed under polythene sheet.
Edges are then taped down to the table.
A valve and vacuum pump suck out all the air and so the resulting pressure pulls the laminates hard together

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4
Q

Benefits of lamination

A

Aesthetically pleasing
Versatility, can make whatever thickness desired
Affordability, much cheaper than buying solid wood and cutting it out (less wastage too)
Less liable to warping and cracking as reinforced
Increased strength

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5
Q

Disadvantages of lamination

A

Potentially more labourious as mould needs to be created

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6
Q

What is an adhesive?

A

A substance used to stick materials together

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7
Q

What are the two main types of adhesives?

A

Cascamite

PVA

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8
Q

What is cascamite?

A

Strong glue used when laminating flexible plywood together.
3 parts cascamite and one part water
Sanded once dry for smooth finish
Dries in 24-48 hours

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9
Q

Advantages of cascamite?

A

Weatherproof

Strong even at high temp

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10
Q

Advantages of PVA?

A

Waterproof
Readily available
Dries clear
Affordable

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11
Q

Why cascamite over PVA?

A

Stronger under sharp temp changes
Weatherproof not just water proof
Stronger in general

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12
Q

Why PVA over cascamite?

A

More readily available
Dries clear and faster
Still waterproof
Versatile

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13
Q

Cascamite typical uses

A

Anything outdoors

etc, boats, dinghy’s

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14
Q

Name three types of composite wood

A

MDF
Hardboard
Chipboard
Plywood (flexy ply)

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15
Q

Advantages of using composite wood

A

Cost effective when needing curves (don’t have to buy big lump of timber or machinery)
Versatility
Doesn’t have weak points which natural wood is prone to having (no warping or cracking)
Normal woods can have splits and shakes

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16
Q

Uses and features of plywood

A

Odd number of layers of veneer glued together at right angles
Can be stained or painted
Used in shelving and construction due to its strength

17
Q

Uses and features of chipboard

A

Compacted wooden chips which is laminated
Strong, but not water resistant
Protects items better than corrugated in shipping
Used in flooring and veneered worktops

18
Q

Hardboard features and uses

A

Made from exploded wood fibres to increase the density
Less durable and unnatural finish but can be painted and oiled
Quite cheap
Used in furniture and construction

19
Q

MDF uses and features

A

Made from normal wooden fibres
Dense but not as dense as hard board
Not water resistant
Commonly used in decorative furniture etc

20
Q

Who is related to the arts and craft movement and what did he do?

A

William Morris

British textile designer, poet, novelist, translator, painter, and social activist. Significant in the revival of British textile arts and textile construction methods.

21
Q

What are the features of the arts and craft movement?

A

Raw materials with natural qualities and beauty
Designs, motifs and patterns inspired by nature
Natural materials
Craftsmanship (eg hand printing) and experimentation
Natural colour tones
Belief that all objects that surround a person should be of good quality and well made
Simplicity
Form follows function
Affordability to appeal to wider community
Proportionality

22
Q

What years did the arts and crafts movement last

A

1880-1920

23
Q

What are the 5 polymer processes

A 
Injection moulding
Rotational moulding
Blow moulding
Extrusion
Vacuum forming
24
Q

What is anodising?

A

Enhance the natural oxide layer via electrolysis to increase hardness and toughness

25
Q

MIG welding over one solid piece

A

More wastage of material

Individual parts can be adjusted and used elsewhere

26
Q

Solid over MIG

A

Faster cycle times on CNC
Aesthteivally pleasing
Less labour time

27
Q

Benefits of ABS

A

Hard

Non toxic

28
Q

Rotational moulding

A
29
Q

What is die casting?

A
30
Q

Advantages of high pressure die casting?

A

Ability to create thin walls of exact dimensions
Create large volumes of complex products in short times leading to lower lead times which is more cost effective
Has a good surface finish

31
Q

Disadvantages of high pressure die casting?

A

Porosity caused by entrapped gases, resulting in weak points and potentially ruining aesthetic
High startup costs, not effective for small scale production runs
Finished products cannot be fully heat treated

32
Q

Setup of CNC machine

A

Design product on CAD software
Ensure machine knows which tool is being used (number of teeth, size etc)
Tell machine which material is being used and the speed (rpm) feed rate and speed
Align tool to the datem point (origin 0,0)
Test cut without material
If all is ok then put material in and line up with datem point
Send around at a 50% rate to ensure it works
Carry out an inspection (quality check) and then peer assess

33
Q

Advantages of sand casting

A

Simple production process
Low cost moulds and therefore low production costs with short lead times
Wide material choice with complex shapes able to be made
Easily repeatable
Ideal for one off production

34
Q

Disadvantages of sand casting

A

Low dimensional accuracy
Rough surface finish
Predominantly handmade so more liable to small errors which could result in unstable casting quality

35
Q

How does rotational moulding?

A
  1. A hollow mould created using CAD software
  2. Mould with plastic in pellet form or powder
  3. This is heated to 300 degrees Celsius and then rotated about 2 axes
  4. During the rotation the mould is heated causing the polymer to melt and then “lay up” on the sides of the mould, evenly dispersing it.
  5. Once fully melted it is moved into the cooling station where cool air surrounds the mould
  6. This causes the plastic to solidify, once solid rotation stopped and product removed
36
Q

Advantages of rotational moulding

A

Even stress levels so walls have even thickness limiting number of weak points
Can make very large components
Low mould equipment costs
Easy colour and mould changes
High strength and stability due to thick corners and lack of exposure to external pressure

37
Q

Disadvantages of rotational moulding

A

Only simple shapes
Limited material choice, as has to be in powder form
Limited mechanical properties due to thick walls
High cycle times
Poor dimensional tolerance control

38
Q

Positive obsolescence

A

Newest products, apple iPhone, status symbol

Safety, after length of time products can be harmful (eg a battery), risk to your health as user

Design And Technology (18 decks)

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