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glassworking > glass working > Flashcards

glass working Flashcards

1
Q

majority of glass is used in

A

packaging e.g. jars, bottles

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2
Q

glass also used in

A

construction e.g windows
transport applications

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3
Q

challenges glass presents as a production material

A

1)high energy consumption (melting raw materials to produce glass)
2)handling and transport (glass fragile)
3)quality control (consistent, free from defects e.g. bubbles, stresses) during manufacturing
4) temp sensitivity (carefully cooled to avoid stresses that leads to breakage/defects–precision)
5) produces waste materials, can be recycled but process must maintain quality, avoid contamination

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4
Q

3 key features of glass shaping

A

1) precision molding (using molds to shape molten glass in specific forms, ensure accurate and uniform)
2) blowing (molten glass inflated into a bubble, then shaped by blowing air through pipe)
3) pressing (molten glass pressed into molds using plunger, creates precise shapes, smooth surface)
4) drawing (molten glass pulled into thin strans/sheets–glass fibres, window panes)
5) rolling
6) cutting and grinding
7) tempering and annealing

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5
Q

contempory glass production has a x degree of y

A

x: high
y: automation

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6
Q

Material removal processes can be {1}. Glassworking is principally a set of { 2 } techniques. Glass has a unique set of properties: {3,4,5}. Glass is the most { 6 } material.

A

1: challenging/difficult
2: hot-shaping
3, 4, 5: chemical, mechanical, aesthetic
6: widely recycled

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7
Q

main component of glass

A

Silica

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8
Q

Other components of glass

A

soda ash, limestone, aluminium oxide (potash)

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9
Q

recycled glass ({1}) is typically added up to {2}% of the charge

A

1: cullet
2: 50

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10
Q

after the batch is mixed, it’s {1} in a furnace {2: x-y °C) to obtain {3} glass for {4}

A

1: heated
2: 1500-1600
3: molten
4: shaping

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11
Q

the melting cycle takes between x-y hours

A

24, 48

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12
Q

what type of moulding is ideal for wide mouthed jars and vases

A

press and blow

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13
Q

what type of moulding is ideal for narrow necked bottles? e.g. {1}

A

blow and blow
1: beverages, perfumes

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14
Q

for blow and blow moulding, {1} may be required between the steps and additional {2} and gob feeders may be used to increase {3} rates

A

1: reheating
2: moulds
3: production

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15
Q

what type of moulding process is annealing?

A

blow and blow

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16
Q

annealing is performed in { 1 } (lehrs), heating and {2} cooling the glass to { 3 }

A

1: tunnel like furnaces
2: slowly
3: resolve residual stresses

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17
Q

In annealing, glass is heated to a temperature just {1} its melting point. Making it pliable without causing a change in its {2}. At this high temperature, the { 3 } within the glass relax and redistribute themselves more {4}. The key part is the { 5 } phase, this {6} reduction in temperature allows to glass to { 7 }.

A

1: below
2: shape
3: internal stresses
4: uniformly
5: slow cooling
6: gradual
7: uniformly solidify

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18
Q

slow cooling helps to minimize {1} by { 2 }

A

1: stresses
2: even solidification

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19
Q

if the glass were quickly cooled, different parts/areas would {1} at different {2}, leading to the formation of new {3}

A

1: contract
2: rates
3: stresses

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20
Q

during the cooling process, any { 1 } that were present due to {2} cooling or handling during {3} are relaxed. Resulting in a more {4}, { 5 } glass structure

A

1: residual stresses
2: uneven
3: formation
4: stable
5: stress free

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21
Q

the process of annealing ensures what

A

the final product is stronger, less likely to crack or shatter due to internal tensions

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22
Q

what does annealing improve

A

durability and longevity of glass (making it suitable for various applications)

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23
Q

what is a residual stress, is it temporary? What’s the cause of it?

A

internal stress
remains in a member of the weldments after a joining operation
generated by localized, partial yielding during the thermal cycle of welding and the hindered contraction of these areas during cooling.

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24
Q

in glass production for a continuous furnace, what’s the purpose of the molten tin bath?

A

allows molten glass to evenly spread forming a flat sheet of uniform thickness, before annealing

25
Q

Purpose of rolling of flat plate glass

A

forming rolls enable mechanical shaping of the glass, offering great thickness control and variation across the line

26
Q

In terms of optical precision, is the float process for producing sheet glass, or the process of rolling of flat plate glass higher?

A

float process has higher optical precision

27
Q

what’s meant by a high optical precision?

A

high ability to produce glass components of very accurate shape and smooth surface

28
Q

what’s the importance of a high optical precision process?

A

high level of precision, crucial in sensitive applications were tiny imperfections impact performance

29
Q

give an example of product requiring a high optical precision process

A

camera lenses, telescope, microscope, other optical instruments

30
Q

what is precision glass moulding

A

high optical precision process, involves heating glass blankets, shaping into ultra-precise moulds

31
Q

The result of precision glass moulding is optical components with complex {1} and minimal { 2 }, ensuring {3} performance in {4} systems

A

1: geometries
2: surface defects
3: optimal
4: optical

32
Q

Glass is inherently {1}, {2} can solve this

A

1: brittle
2: toughening/tempering

33
Q

During glass tempering, stresses are { 1 }. Glass is heated above its {2} temperature (approx {3}°C), to push it into the {4} range

A

1: strategically induced
2: annealing
3: 650
4: plastic

34
Q

what happens after glass is heated above the annealing temperature and is pushed into plastic range?

A

surface is quenched, causing it to harden around the plastic interior

35
Q

when very hot glass surfac e is quenched, it hardens around its {1} interior which cools more {2}

A

1: plastic
2: gradually

36
Q

products that involve glass tempering are …

A

windows for tall building, all glass doors, safety glasses

37
Q

why do windows, specifically for tall buildings, require glass tempering?

A

1: safety–tempering is stronger, when glass breaks it shatters into small less harmful pieces (as opposed to large, sharp shards),
2: wind pressure– tall buildings subjected to higher wind pressures, tempered glass more effective at withstanding these forces
3: thermal stress– tall buildings experience greater temp variations between inside and outside, can cause untempered glass to crack due to thermal stresses

38
Q

true or false:
may building codes and regulations require glass to be tempered when used in high rise buildings

A

true
(safety reasons)

39
Q

two disadvantages of tempered glass…

A

1– cost, additional process
2–alteration limitations00ince tempered, can’t be cut, drilled or altered, these modifications must be done prior to tempering
3–weaker in tension–strong under compression, less so under tension–more susceptible to breakage if exposed to extreme bending stresses
4– distortion, the process can introduce slight optical distortions– bad for applications requiring high visual clarity

40
Q

why can’t tempered glass be cut or drilled?

A

unique internal structure created during tempering:
-internal stress–caused from rapid cooling, stresses formed from this make glass stronger, but sensitive to further modifications
-risk of shattering– cutting/drilling disrupts the balance of these internal stresses, causing glass to shatter into many small pieces due to uniform stress distribution, alterations cause stresses to suddenly release

41
Q

true or false:
Once glass has been tempered, it is set in its final stress induced state, and cannot be altered without breaking

A

true

42
Q

describe the difference between rolling and cutting&grinding

A

rolling-molten glass passed through rollers to produce flat sheet–architectural glass
cutting & grinding– shaping glass post production to achieve desired dimensions and finish (polishing too)

43
Q

describe tempering and annealing

A

process to strengthen glass and reduce internal stresses, making more durable and stable

44
Q
A
45
Q

developments and advancements

A
46
Q

the three basic types of ceramics are

A

glass, traditional ceramics, new ceramics

47
Q

glass is distinguished by its {1} structure, other ceramic materials have a {2} structure

A

1: non-crystalline (vitreous)
2: crystalline

48
Q

glass products commercially produced in an unlimited {1} of shapes, at {2} quantities

A

1: variety
2: high/large

49
Q

three glass products…

A

light bulbs, jars
window glass
glass tubing e.g. fluorescent lighting
glass fibres
glass telescope lenses (made individually)

50
Q

difference between glass and traditional & new ceramics

A

glass is vitreous–in glassy state, exhibits the smooth, often shiny and translucent properties
the other two are large polycrystalline materials

51
Q

3 basic steps in glassworking sequence

A

1) raw material preparation and melting
2) shaping
3) heat treatment/finishing operations (e.g. grinding, polishing, etching) if needed

52
Q

3 types of melting furnaces

A

1) pot furnace
2) day tank
3) continuous tank furnace
4) electric furnace

53
Q

describe process of one of the melting furnaces

A
54
Q

describe the spinning process in glassworking

A

similar to centrifugal casting in metal working
gob of molten glass dropped into a conical spinning mold, causing centrifugal force to spread the glass upward onto mold surface

55
Q

difference between press&blow and the blow&blow shaping processes

A

for press&blow, initial forming step involves pressing part, for latter; first step is blowing

56
Q

describe spinning process in glassworking

A

glob of molten glass, dropped into conical spinning mold, causing centrifugal force to spread the glass upward onto the mold surface

57
Q

difference between press and blow, and blow and blow shaping process in glassworkingg

A

press and blow–initial step pressing the part

58
Q

describe a way of shaping plate or sheet glass

A

1) rolling–hot glass squeezed between opposing cylindrical rolls
2) float process–melted glass flows onto a molten tin surface to achieve uniform thickness and smoothness

59
Q

describe the Danner process

A

molten glass flows around rotating hollow mandrel, where air is blown while glass is drawn.
Air temperature, its volumetric flow rate, and drawing velocity determine diamter and wall thickness of tubular cross section
during hardening glass tube supported by series of rollers extending beyond mandrel

glassworking (6 decks)

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