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Design > Vacuum Forming > Flashcards

Vacuum Forming Flashcards

1
Q

What is the recommended minim draft angle for vacuum forming?

Lim.l

A

3 degrees

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2
Q

What is vacuum forming?

Ivan K

A

Vacuum forming is a simplified version of thermoforming, where a sheet of plastic is heated to a forming temperature, stretched onto a single-surface mold, and forced against the mold by a vacuum. This process can be used to form plastic into permanent objects such as turnpike signs and protective covers.

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3
Q

What can you make with vacuum forming?

Ivan K

A

This process is used to create many of the products in your home such as plastic containers, tubs, sink units, and electrical enclosures.

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4
Q

Which thermoplastics can be used in vacuum forming?

Ivan K

A 
Acrylonitrile Butadiene Styrene (ABS)
Acrylic - Perspex (PMMA)
Co-Polyester (PETG)
Polystyrene (HIPS)
Polycarbonate (PC / LEXAN / MAKROLON)
Polypropylene (PP)
Polyethelene (HDPE)
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5
Q

What are the steps in vacuum forming?

Ivan K

A

MAKE THE MOULD
Firstly, a mould is constructed in the shape that the plastic will form around. This mould can be in a variety of different materials, including wood, MDF or polystyrene. Often where possible, the mould should have angled edges. This will allow the product to pop out of the plastic when the vacuum forming is finished.

PLACE THE MOULD INTO THE VACUUM FORMER
Once made, the mould is placed into the vacuum former. A plastic sheet should then be clamped above, but not on, the mould.

POSITION THE HEATER ABOVE THE PLASTIC
The heater in the vacuum former should then be positioned above the plastic. This will eventually heat up, warming the plastic and ensuring that it is perfectly flexible and mouldable.

MOVE THE SHELF TOWARDS THE PLASTIC
After a few minutes, the plastic should be at the correct temperature to allow moulding. Once this is the case, the shelf on which the mould is positioned should be moved upwards and into the plastic. You can use a handle to do this.

SWITCH THE VACUUM FORMER ON
The vacuum former will then be switched on, which removes all air from the machine. This will allow the plastic to form to the shape of the mould.

REMOVE THE SHEET FROM THE VACUUM FORMER
Once it has cooled, remove the plastic sheet from the vacuum former. Remove the mould from the machine and then trim any excess or unwanted plastic from the formed sheet.

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6
Q

What is a good tip for when you design a mold for vacuum forming?

Ivan K

A

When designing a mold for vacuum forming consider drafting angles. Drafting angles allow your molded part to be removed from the mold. They should typically be anywhere from 3-5 degrees from 90 on any vertical surface

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7
Q

Why do you want lots of holes around your mould when vacuum forming?

-Oscar Lawson

A

So that you don’t leave cavities in your formed plastic caused by lack of suction

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8
Q

How much tapering is needed for a good draft?

-Oscar Lawson

A

At least 5 degrees

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9
Q

What are a few real world example of vaccum forming?

-Oscar Lawson

A

Bathtubs, boats, slides, trailers

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10
Q

Why would you reverse the vacuum in the vacuum forming machine?

-Oscar Lawson

A

To blow air into the mould, releasing it from the plastic

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11
Q

What are thermoplastics?

-Oscar Lawson

A

Long chain molecules held together by Van Der Waals forces of attraction. They can be reheated and shaped many times.

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12
Q

Rearrange these processes of Vacuum Forming:

A. Clamp the plastic sheet in place so that there is an air tight seal.

B. Place the mould on the plate and lower it.

C. Once cool, reverse the air pressure and tap the plastic to release the moulding.

D. Switch on the pump and raise the platen.

E. Pull the heater over the plastic sheet and heat until softened ( Just begins to sag ).

  • Humphrey Marsh
A
  1. B
  2. A
  3. E
  4. D
  5. C
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13
Q

Why is the mould in vacuum forming designed with a draft (tapering sides)?

  • Humphrey Marsh
A

To enable the plastic to be removed after moulding.

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14
Q

When there are fewer holes on the edge of the mould, what occurs?

  • Humphrey Marsh
A

Spaces are formed due to lack of suction.

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15
Q

With the vacuum forming machine, is it possible to reverse it and blow air into the moulding to release it from the mould?

  • Humphrey Marsh
A

Yes, it is in fact possible to do this and this is done by blowing air into the mould to release it from the mould.

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16
Q

What does the thermoplastic ‘HIPS’ mean?

  • Humphrey Marsh
A

High impact polystyrene sheet

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17
Q

What does the mould have to include?

Yan K

A

Small holes around its periphery

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18
Q

What thermoplastics are most commonly used?

Yan K

A 
Polythene
PVC
ABS
Acrylic
HIPS
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19
Q

How does the mould have to be designed as?

Yan K

A

With tapering sides (draft) to enable it to be removed after moulding

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20
Q

What is the first step of the vacuum forming process?

Yan K

A

Place mould on the plates and lower it.

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21
Q

What is the second step of the vacuum forming process?

Yan K

A

Clamp plastic sheet in place so that there is an air tight seal.

22
Q

What is are examples of the application of vacuum forming

-Krystian Shanahan

A

Baths , slides etc

23
Q

Why does the mould in vacuum forming require holes.

-Krystian shanahan

A

To increase the suction

24
Q

Why does the mould need to be design with a draft

-Krystian Shanahan

A

So that’s the mould can be removed after the vacuum forming

25
Q

What is a draft?

-Krystian shanahan

A

Tapered sides (sides that stick out )

26
Q

What sort of plastic is used in vacuum forming and why?

-Krystian shanahan

A

Thermoplastics as it can be reshaped when heated

27
Q

Which is better in the mould: more holes or less holes?

-Ssnehnil Ghosh

A

More holes

28
Q

How many main steps are there?

-Ssnehnil Ghosh

A

5 main steps

29
Q

Why can’t thermosetting plastics not used?

-Ssnehnil Ghosh

A

They can’t be reshaped

30
Q

What type of process is vacuum forming?

-Ssnehnil Ghosh

A

A deforming process

31
Q

What does HIPS stand for?

-Ssnehnil Ghosh

A

High Impact Polystyrene Sheet

32
Q

Why are thermosetting plastics not used?

Torsai K

A

They can only be heated once, and once covalent bonds have set, it cannot be reshaped again.

33
Q

What are the main steps in the vacuum forming process?

Torsai K

A
  1. Place the mould on the platen and lower it.
  2. Clamp the plastic sheet in place so that there is a tight seal.
  3. Pull the heater over the plastic sheet and heat until softened.
  4. Switch on the pump and raise the platen.
  5. Once cool, reverse the air pressure and tap the plastic to release.
34
Q

What type of plastics are used in vacuum forming, and why?

Torsai K

A

Thermoplastics, because unlike thermosetting plastics, they can be reheated and therefore reshaped multiple times.

35
Q

What type of process is vacuum forming?

Torsai K

A

It is a deforming process.

36
Q

Why do moulds have small holes around its periphery?

Torsai K

A

Better contact, and better suction. More holes = better suction.

37
Q

Why is a draft used in vacuum forming?

-Lucas M

A

To enable it to be removed easily

38
Q

Why might the vacuum be reversed?

-Lucas M

A

To release it form the mould.

39
Q

How does vacuum forming work?

-Lucas M

A

A thermoplastic sheet is heated until soft. A vacuum is created between the sheet and the mould, pulling the sheet over the mould so that it takes the form of the mould. The sheet is allowed to stiffen and is removed from the mould.

40
Q

Which plastic is used for vacuum forming?

-Lucas M

A

Thermoplastics plastic.

41
Q

What thermoplastics are commonly used?

-Lucas M

A 
Polythene
PVC
ABS
HIPS
Acrylic
42
Q

“A thermoplastic sheet is heated until … “

-Alfie Turner

A

soft

43
Q

List the types of thermoplastics that are commonly used

-Alfie Turner

A 
Polythene
ABS
PVC
Acrylic
HIPS
44
Q

Why does the mould have to be designed?

-Alfie Turner

A

To enable it to be removed after moulding

45
Q

Is a bath a vacuum formed product?

-Alfie Turner

A

YES

46
Q

Is a slide a vacuum formed product?

-Alfie Turner

A

YES

47
Q

Should your mould include small holes around its periphery?

-Oscar Mabon

A

Yes

48
Q

If a mould didn’t have tapered sides would it be easy to remove after moulding?

-Oscar Mabon

A

No

49
Q

Can Acrylic be used in Vacuum forming?

-Oscar Mabon

A

Yes

50
Q

Can Nylon be used in vacuum forming?

-Oscar Mabon

A

No

51
Q

What is the name of the plate that you place the mould on?

-Oscar Mabon

A

The Platen

Design (31 decks)

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