Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

(GCSE) Design And Technology > Polymers And Commerical Printing + Manufacturing Processes (Y10 - Autumn 2) > Flashcards

Polymers And Commerical Printing + Manufacturing Processes (Y10 - Autumn 2) Flashcards

1
Q

What are Polymers/Plastics?

A

Most plastics are made from crude oil. After refining, chemical reactions produce a large number of identical molecules called monomers which are then combined together to form long strands called polymers. All plastics are types of polymers.

Plastics can also be made from plant oils in other words from renewable materials, these plastics are called ‘Bioplastics’, but are still quite rare.

  • Polymers are more commonly known as plastics
  • Introduction into customer products 1950’s
  • Most manufactured by non renewable resource: Crude Oil.
  • Chemical engineers constantly looking for environmentally
    friendly alternative options.
  • They come from two main families.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are Thermoforming Polymers?

A

These plastics can be re-heated and therefore shaped in various ways. They become mouldable after reheating as they do not undergo significant chemical change. Reheating and the pastic makes the bonds between the molecules weaker, and weaker, so the molecules are now free to move, and therefore be reshaped. These types of plastics can be recycled.

Thermoplastics soften when heat is applied and can easily be formed into shape by a number of different methods. Plastic can be softened and reshaped, or be made molten.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are Thermosetting Polymers?

A

Once ‘set’ these plastics cannot be reheated to soften, shape and mould. The molecules of these plastics are cross linked in three dimentions and this is ehy they cannitbbe reshaped or recycled. The bond between the molecules is very strong.

Thermosetting plastic must be formed into a shape from their stock form (Powder or Ganules) and cannot be reformed)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the Pros and Cons of Thermoforming Polymers?

A

Pros:

  • Highly recyclabe
  • Aesthetically-superior finishes
  • High Impact resistance
  • Remoulding/Reshaping capabilities
  • Chemical Resistant
  • Eco friendly manufacturing

Cons:

  • Generally more expensive than thermosetting plastic
  • Can melt if heated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the Pros and Cons of Thermosetting Polymers?

A

Pros:

  • More resistant to high temperatures than thermoplastics
  • Highly flexible design
  • Thick to thin wall capabilities
  • Excellent aesthetic appearnace
  • High levels of dimentinal stability
  • Cost effective

Cons:

  • Cannot be recycled
  • More difficult to surface finish
  • Cannot be remoulded or reshaped
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Thermoforming Polymer: Acrylic (PMMA)

Example Use + Properties/Uses

A

Example Use: Rear Car Light

Acrylic is quite a hard and brittle material, while is also used in car light units, as well as acrylic baths and shop signs, as they are a translucent material, which lets light through it. It is not very bendable at all, and can just be smashed and crack if it takes a hit.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Thermoforming Polymer: High Impact Polystyrene (HIPS)

Example Use + Properties/Uses

A

Example Use: Plastic Yogurt Pots

It can be squashy but it quite flexible and can usually goes get itself back into place is it is squashed, meaning it won’t just crack easily or fall apart.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Thermoforming Polymer: High Denisty Polythene (HDPE)

Example Use + Properties/Uses

A

Example Use: Plastic Bucket

High Density Polythene is quite hard and not very bendable, meaning it stays stiff and sturdy, meaning it is ready for everyday use, which means it used to some wear and tear.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Thermoforming Polymer: Polypropylene (PP)

Example Use + Properties/Uses

A

Example Use: Plastic Chair

Polypropylene needs to be strong in it’s structure, as it needs to hold the weight of a person on it, meaning it still needs a bit of flexibility, along with it’s hard and strong nature, meaning it can withstand a bit of force and not to just crack/crumble.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Thermoforming Polymer: Polyvinyl Chloride (PVC)

Example Use + Properties/Uses

A

Example Use: The Plastic Around Windows

Polyvinyl Chloride (PVC) needs to be chemical resistant, meaning it also needs to be resistant to ultraviolet rays (UV rays) from the sun. Also it needs to be relatively water resistant, sturdy and strong.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Thermoforming Polymer: Polyethylene Terephthalate (PET)

Example Use + Properties/Uses

A

Example Use: Pastic Bottles

Polyethylene Terephthalate (PET) is a very recyclable plastic that can be recycled many times, as long as it is recycled along with the same type, and stays as the same type. *These plastics need to be heat resistant and moisture resistant as well.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Thermosetting Polymer: Epoxy Resin (ER)

Example Use + Properties/Uses

A

Example Use: Essentially Guing Things Together (like Super Glue)

Epoxy Resin can be used as an adhesive, that is a thermosetting plastic, meaning it will be unchangeable (permanently). This is because it comes in two tubes, with an adhesive being one, with a hardener applied with it. (The hardener acts as a catalyst which creates a rection.)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Thermosetting Polymer: Melamine-Formaldehyde (MF)

Example Use + Properties/Uses

A

Example Use: Kitchen Worktops

Melamine-Formaldehyde (MF) is a very thin, brittle layer (less than a mm) of very hard plastic that is very smooth, easy to clean and is heat resistant, which is why it will be used for tables and kitchen worktops. (As this is used over a cheap piece of chipboard which makes it look better.)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Thermosetting Polymer: Phenol Formaldehyde (PF)

Example Use + Properties/Uses

A

Example Use: Handles of Saucepans

Phenol Formaldehyde (PF) is something that can be used for pan handles and grill handles, meaning it is resistant to extreme heat, meaning it does not conduct heat very well at all.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Thermosetting Polymer: Polyester Resin (PR)

Example Use + Properties/Uses

A

Example Use: The Outside Of A Small Boat.

Polyester Resin (PR) is similar to Epoxy Resin in the fact that there is a resin and a hardener, whereas this time, there is more resin than the hardener. This plastic holds it’s shape very well, but it is not a very strong material when impacted, but can be used to fix up things easily.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Thermosetting Polymer: Urea-Formaldehyde (UF)

Example Use + Properties/Uses

A

Example Use: The Outside of a Plug Socket

Urea-Formaldehyde (UF) is the type of plastic that plug sockets and light switches are made out of. It is very, very hard, but very, very brittle whenever it does break. It is used for electrical fitting as it has a very high resistance to heat and electrcity which is generated by large amounts of power-flow.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What do Plasticisers do?

A

Plasticisers makes plastics a bit more soft, meaning the plastic will be made more flexible.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What do Pigments do?

A

Pigments change the colours of a plastic to mean the plastic is coloured.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What do Stabilisers do?

A

Stabilisers gives plastics protection against something, for example UV stabilisers protect them from UV rays.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What do Fillers do?

A

Filers will make plastics a bit tougher and stronger, giving it a bit more resistance.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

New and Smart Materials: Carbon Fibre

A

Example Use: Bike

It is a lightweight and very strong material, which is used in many products that need to be strong, but lightweight, as well as it being made more expensive by the cost of making it. Carbon Fibre is a composite material (made up of different materials: carbon fibre strands + resin).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

New and Smart Materials: Teflon

A

Example Use: Frying Pan

The main advantages of using Teflon are ensure that things do not stick together, meaning it is used for cooking, with it being put in saucepans to ensure food doesn’t stick to it. Teflon is a polymer, meaning it is plastic based.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

New and Smart Materials: Biopolymer

A

Example Use: Single-Use Food Containers

Biopolymers are new materials that have the properties of plastic, but are manufactured from plant materials instead of oil. Unlike traditional polymers, they are biodegradable and can be composted safely. Biopolymers are NOT recyclable, Biopolymers are Biodegradable, meaning they can be composted.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

New and Smart Materials: Thermochromic Material

A

Example Use: Bath Termomemter

Thermochromic materials change colour with changes in temperature. The change in colour happens at a determined temperature, which can be varied to suit different products. Thermochromic pigments can be put into other materials, and therefore put into a range of different products.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

New and Smart Materials: Photochromic Material

A

Example Use: Sunglasses Lens

Photochromic materials change colour with changes in UV light. When sunlight or ultraviolet radiation is applied the molecular structure of the material and changes it exhibits colour. The colour makes the lens darker. Once the UV light is removed, the colour disappears.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

New and Smart Materials: Fluorescent Material

A

Example Use: Hi-Vis Jackets

Fluorescent materials produce light when exposed to UV rays. This makes them particularly useful for high-visibility clothing, but is only effective when there is UV light (i.e day), meaning that it will be less bright and reflective when it is dark, as there is no UV light to reflect.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

New and Smart Materials: Phosphorescent Material

A

Example Use: Grow In The Dark Lights

Phosphorescent materials produce light as a result if being exposed to a light source. Light energy is absorbed and then released slowly over time as light. Glow-in-the-dark stickers are a common use of phosphorescent materials, because of it’s quality to slowly release light overtime.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What does CMYK stand for

A

C - Cyan
M - Magneta
Y - Yellow
K - Black

Most printers that do Offset Lithography will use the CMYK colour scheme to print out the images.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

It is known as CMYK printing. Why is black K and not B?

A

Black is K and not B, because it is the ‘Key’ colour for creating images, as Black is able to add depth, as well as tone into images. This means without the black, images would not look/seem right. Also, B needs to be used for other colours such as Brown or Blue.

31
Q

What are the lines in the corners of the image used for?

A

These crosses, are to make sure that the sheets and plates are all aligned with each other.

32
Q

Why are there blocks of colour underneath the image?

A

There are blocks of colour under the image to show the colours used in making the image.

33
Q

What is the circle with a cross in used for on the bottom on the page?

A

The circle with a cross is used for lining up everything in the right order.

34
Q

The printing process is knows as Offset printing. What does this mean in relation to the way the image is printed onto the paper?

A

Offset printing is when the ink is tranferred onto the plate cylinder, and then put onto the blanket cylinder with water, and is then rolled onto the paper afterwards. This is why it gets the name of ‘offset’ because the ink isn’t directly applies to the paper.

35
Q

A typical offset lithography press used in commercial printing. This has four sections for the CMYK colour separations. However, there are other types or these printers that have six sections. What might the other two be used for?

A

The other two sections could be used for applying special colours, such as gold, silver, bronze, as well as white ink too. Other things like fluorescent colours and special inks can be put in these final 5th and 6th sections too.

36
Q

How cost effective is offset lithography for the following quantities? Explain your reasons:

50 A4 Posters:
5000 A4 Posters:

A

50 A4 Posters:
This won’t be very cost effective because it is a very long and costly process, which takes time to set up, and this wouldn’t be made the most of if it was only printed 50 times, and could be done cheaper using a different process.

5000 A4 Posters:
This would be a lot more cost effective because here, you would be making the most of the amount of setup that is needed, and therefore making the process of printing 5000 things a lot better and higher quality than just using a cheaper method of printing.

37
Q

The colour black can be created by using the other three colours together. Why is there a separate black colour used in the process?

A

The seperate black is used because no other combination of colours can be used in order to create a true and full black. Also pure black can be used well for toning and definining a piece of printing.

38
Q

What happens when a coloured ink runs out

A

When one of the coloured inks runs out of cartridge, the image will not print properly, possibly resulting in the image printing is a wierd colour (or just in greyscsale), or the image just not being able to be printed at all.

39
Q

The school commendation card gets re-printed from time to time in batches of around 2000. The costs for reprinting are much less than the original batch we had printed. Why would this be?

A

The costs of reprinting will be far less because you will already have manufactured the necessary plates that are shaped and made in the right way for what you want to print, which is the main initial cost that makes it more expensive, but these can be re-used again, so now you will only need to pay for the setup of the machine, as well as the ink being used.

40
Q

Computer monitors do not always display CMYK colours very accurately, as they use an RGB system to generate the colour reporduction. What is the difference between RGB and CMYK?

A

The difference between RGB and CMYK is that in the RGB system, you have the colours Red, Green, and Blue are used, while in the CMYK system, you have the colours Cyan, Magenta, Yellow, and Black. The reason why these different systems are used between monitors and printed images are because it is to do with the way that we see light. In a monitor, the light is being projected from the screen, while in a print, the colour that you want needs to get reflected by light for you to be able to see it. This is why when you preview a print on a computer, the colours will look slightly different to when it is in real life.

41
Q

Why do we produce products in different volumes?

A

We produce products in different volumes mainly because of the demand, meaning a larger supply of this product will need to be made for the demands to be met and reached. Furthermore, products will not be produced in huge amounts when their demand could be at risk or is not predictable. For example there will not be huge production of USB sticks, as they are getting higher, and higher quality as time goes on, resulting in a big warehouse of products that are not worth as much as they initially were.

42
Q

How do production volumes affect production techniques?

A

Products with higher production volumes will need to be produced in larger volumes and batches, which will meaning that their costs to make will usually be mechanically manufactured and therefore mass produced. Products with lower prodcution volumes will be more ‘one-off ‘, as they won’t be mechanically produced by robots and machinery, and will more likely be done by more skilled craftsmen (as the product will need to be catered to the customers needs), making it more unique and bespoke, however, this will most likely make it more expensive. Also, the product will be made for the needs at that moment.

43
Q

What is:

  • One-off production
  • Batch production
  • Mass production
  • Continous production
A

One off Production - (More skilled human workers) - More time consuming

Batch Production - (A large amount can be made, but in batches, you can try to make as many of the products as you can sell) - This can be done seasonally with sunscreen, and can be done in shelf life in food.

Mass Production - (Involves machinery more in it’s production and is done in masses, but is very expensive to set this up, but if you know the product will sell long term, then you will eventually make the money back).

Continuous production - (Still uses a lot of machinery, and is designed to make one product 365 days a year non-stop, hence, it’s continuous. These production lines are made exactly for this specific need) - Very expensive to set up but can pay off in the long term.

44
Q

One-off Production Examples

A

Houses of Parliament:

This is a one off building because it was specifically made for this one purpose, and will not be made again, because you simply cannot have two House of Parliament because it is not viable. This is why a one off production is the best option in this scenario.

45
Q

Mass Production Examples

A

PS4 Production:

The PS4 is a good example of mass production because it is produced on a huge scale, knowing that there will be lots and lots of sales when it is released, and also in the future. This means that although it will be expensive to set up the machines and manufacture the product, the money will eventually be made back in future revenue.

46
Q

Why do you think one-off products have a high unit cost (why are they more expensive to manufacture)?

A

One off products will have a higher unit cost when compared to other manufactured products becuase this will require a unique design to be created, with a skilled craftsman with the materials, tools, as well as the skill to be able to create a totally bespoke product, with it be catered to your needs as well. This in turn, adds value to the product, and therefore makes it more costly in it’s units.

47
Q

What are the cost implications of mass production?

A

Mass Production can be quite a costly method of manufacturing prodcuts up front, meaning it comes with an element of risk if doing it as either a relativly unknown company, or if the product is relativly unused aslo. This is because the machinery has to be specially set out and formatted to mechanically create the parts of the product and put it together in large bulks, and when puuting this cost together with the price of the materials used, it can amount to quite a bit. On the other hand, if the product made is a success, there is a good amount of stock made and ready, resulting in profit in the future (meaning short term pain, long term gain).

48
Q

What Scale of Production is needed for a Tailored Garment (1 unit)

(Advantages and Disadvantages)

A

One-Off Production

Advantages:

  • As it is customised it can be tailored to whatever needs of the client
  • It is a bespoke product, meaning that there is not a single one that is the same
  • It means that you have had a skilled person specifically instructed to create the product that you want, and not done several times by machine.

Disadvantages:

  • This is slightly less cost-effective in terms of it’s cost/expense per unit.
  • You will need to be paying for the service and time out of the person’s day to make it, while also paying for the materials and the customisations that are made for it.
  • It takes a lot more time and effort to create a single unit in comparison to the other ways.
49
Q

What Scale of Production is needed for Shopping Bags (125 units)

(Advantages and Disadvantages)

A

Batch Production

Advantages:

  • The fact that it can be made in batches mean that the designs if these can be change regularly
  • If a certain batch is not making much profit, it won’t affect your net too much
  • If you have started to release the product and improvements can be made, then they can be made quicker and easier.

Disadvanatges:

  • The fact that these are made in batches means that they won’t be in production 24/7
  • This will be a partly human and partly machine process, meaning people will have to earn a wage, meaning there is more long term expenses.
  • The fact that there are only 125 units per batch, means that if they are high in demand, not a lot of stock will be avaliable.
50
Q

What Scale of Production is needed for a Cutlery Set (5000 units)

(Advantages and Disadvantages)

A

Mass Production

Advantages:

  • This process is all but fully done by machine, meaning these peoducts can be produced throughout most of the day.
  • There will be fewer wages needing to be paid as a result of this
  • There will be a lot of stock made avaliable to the public
  • There will be significant longer-term profits if most of the units are purchased.

Disadvantages:

  • If these units prove not to be popular and the majority of the units produced are not sold, then money will be wasted with a stock pile of useless and non-profitable cutlery.
  • The initial starting up costs prove to be a lot
  • There is not too much room for change and movement with these products, as the machinery already made for making this thing.
51
Q

What Scale of Production is needed for A4 Paper (Constant Supply of units)

(Advantages and Disadvantages)

A

Continuous Production

Advantages:

  • This product can be made 24/7 throughout 365 days per year with nearly all the work being done by machine.
  • There will be a constant supply of this, and theroretically should never run out, therefore meeting the customer demand.
  • There is room for massive profits if the product proves to be a success after the start-up costs

Disadvantages:

  • There will be totally huge upfront costs in creating the machinery with the sole focus in producing one thing.
  • If this one and only product fails, then there will be an awful lot of money spent and also wasted.
  • Any kind of unique or one-off feel is completley lost through continuous production.
  • It’s based on a percieved and average demand, so it will take longer to adjust to the demand.
52
Q

What influences the quantity of products being produced? (In Just In Time Production)

A

The main thing that will influence the quality of the products being produced, is the scale and the demand shown from the order that is placed through to the manufacturing factory. This quantity of the products, as well as the detail and quality will have a knock on effect on how long it will take for the required amount of products to be produced.

53
Q

How does JIT production impact on material stocks?

A

Just-In-Time production will have a big impact on the stock of materials kept and stored in the factory. This is because with JIT production, the materials are ordered to the desired amount, which will be needed to complete each order. This means that there will not be too many stored materials, but can mean there can be too little at certain points, meaning it can take time for the manufacturer to order and get the materials in, in time, possibly leading to delays.

54
Q

What happens to the goods once they come off the production line? (In Just In Time Production)

A

Once the goods come off of the production line, then they are immidiately sent to the customer/consumer. This means that there is as little storage or stock pliling taking place at the factory at all, with the product being shipped out quickly and effectivly, hence the name of the ‘Just-In-Time’ production. This means less storage space is needed, and that the process is as effective and swift as it can possibly be.

55
Q

An Example of a product that id made using Just In Time Production

A

Apple are an example for a company that uses Just-In-Time Production, as this is the model that Apple decide to use.

This means that when a new iPad, or iPhone is made, and manufactured, Just-In-Time production is used so the exact demand is met, and that their manufacturing process can be as efficient as possible. This is especially useful when applying/adding different and personalisable and customisable features on each one.

56
Q

Other Smart Materials:

A
  • Electroluminescent
  • Hydrochromatic
  • Shape Memory Alloy (SMA)
  • Piezoelectric
57
Q

What are the 3 Stock Forms of Plastic and What is ‘Stock Form’

A

Stock form is just about the ‘ingredient’ for the manufacturing methods.

The two main stocks forms plastic can come in are:

  • Sheets
  • Granules

(Can also come in Powder)

58
Q

What is Line Bending

A

One of the simplest ways of forming a polymer sheet. A strip heater consists of hot wire that heats the acrylic up to around 160° (at which the acrylic is pliable and can be bent). Jigs and formers can be used to achieve the desired results. (Don’t overheat the acrylic as it could blister or discolour).

59
Q

Common Uses for Line Bended Products

A

They can be used at shops or banks, where there is a clear plastic screen between the custom and worker, where the plastic is bent at the ends.

(Or a covid screen to keep shop till workers safe)

60
Q

What is Injection Moulding

A

Plastic granules are fed into the hopper, and the screw in the chamber below the hopper sends the granules forward. Heated jackets around the screw melt the polymer. Then the screw winds back and the hydraulic ram comes forward into position. The mould is then closed and sealed as the ram forces the melted plastic into the mould. When the mould is set, the plastic is allowed to cool and the halves of the mould release, before the sprew is machined off.

61
Q

Common Uses for Injection Moulded Products

A

This is the most commonly used process, even though the setup cost is expensive, but it is viable if you are commercially producing a product. An example of a product made from this can be a plastic bucket.

Clues to injection moulding: Shut lines, Sprue marks, Complex shape, Lots of details.

62
Q

What is Vaccum Forming

A

The mould is placed into the former.

A sheet of thermoplastic, such as HIPS is clamped over the mould (it is clamped to make sure a vaccum is kept).

The plastic is slowly heated to become soft.

The former is raised and the air is sucked out, drawing the plastic over the former to take its shape.

The plastic is allowed to cool and then removed from the mould.

The edges must the be trimmed and finished.

63
Q

Common Uses for Vacuum Formed Products

A

An example of a product made by vaccum forming can be a plastic food tray, for example (like for sandwiches or biscuits e.c.t). You can tell it has been vaccum formed as the sides will be slightly tapered.

Also, you cannot really vaccum form a product with an undercut, as you won’t be able to get the mould out.

64
Q

What is Blow Moulding

A

The mould is opened into it’s two halves. A hollow tube of polymer known as the parison is heated.

The parison is lowered into the mould.

The Mould is clamped shut, leaving only a small hole for the air house

Air is forced into the mould at high pressure. The plastic is forced to the mould sides and cools.

(More commonly nowadays, a pre-formed mould can be put into the mould to ensure that the screw part for the lid is of better quality for the bottle tops and e.c.t)

65
Q

Common Uses for Blow Moulded Products

A

Generally, a product that is blow moulded will usually be a product that doesn’t look like it could’ve been taken out of a mould.

This means that things like water bottles will have been blow moulded.
(Clues to blow moulding are the: Shut Line, Spruce Mark, Closed Neck/Hollow Shape)

66
Q

What is Extrusion

A

A motor turns a thread which feeds granules of plastic through a heater.

The granules melt into a liquid/soft and moveable plastic which is forced through a die, forming a long ‘tube like’ shape.

The extrusion is then cooled and formed a solid shape in the cooling chamber.

The shape of the die determined the shape of the tube.

67
Q

Common Uses for Extruded Products

A

Most of the time, a product that is extruded will be a long ‘tube-like’ shape.

Examples of this can be a long tube shape that is made out of plastic.

68
Q

What is Tolerance (in relation to design/engineering)

A

An allowable amount of variation of a specified quantity, especially in the dimensions of a machine or part.

E.g 100mm ± 2mm

69
Q

What is Compression Moulding and How does it work

A
  • Process used for thermosetting plastics
  • The exact amount of plastic is placed in the mould
  • Pressure is used to force the plastic into shape
  • Heat is used to ‘cure’ the plastic into a permanent shape.
70
Q

What is Calendaring and How does it work

A
  • Calendaring is a process where a material is passed theough a series of rollers to create a consistent, flat sheet
  • Extruded material is usually collected on large rollls
  • The rolls can be used to create other stock forms
71
Q

What is Rotational Moulding and How does it work

A
  • Used to manufacture hollow products (often very large)
  • Plastic granules are placed into the mould and the mould is heated and rotated on two axix so the molten plastic covers the surface of the mould
  • Very consistent thickness of plastic and complex shapes
  • Moulds much cheaper than injection or blow moulding as pressure is not required for the process.

(GCSE) Design And Technology (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions