Brainscape's Knowledge GenomeTM

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


See full index

indirect Restoration > Lec 1/19? Investing and Casting > Flashcards

Lec 1/19? Investing and Casting Flashcards

1
Q

Sprue former is attached to:

A

crucible former

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

Direct surround investment material in casting:

A

ring liner, then casting ring

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

investment material must be:

A

heat resistant

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

Benefit of plastic prefabricated sprues:

A

added rigidity, minimizes distortion

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

this can be used for multiple castings:

A

runner bar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

sprue allows for:

A

wax to escape mold, molten metal in

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

is more or less turbulence desired as molten metal flows into sprue?

A

less

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

What provides a reservoir to compensate for shrinkage during solidification of casting alloy?

A

Metal in sprue must remain molten slightly longer than the alloy that has filled the mold

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

What is the crucible former usually made of?

A

rubber

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

Function of crucible former:

A

base for the casting ring during investment

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

Function of casting ring:

A

container for the investment while it sets and restricts the setting expansion of the mold

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

Technique designed to allow unrestricted expansion of casting ring:

A

Ringless casting ring, uses plastic casting ring

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

Investment to use with ringless technique:

A

higher strength, phosphate-bonded investment, usefull for high melting alloys that melt more

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

Function of ring liner:

A

allow more expansion, slightly compressible

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

What to do if you require increased setting expansion of the investment material.

A

Use a 2nd liner

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

How to increase the hygroscopic expansion of the ring liner:

A

wet it

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

TF? Wax has both high CTE and shrinkage.

A

T

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

Why remelt, readapt, and resmooth wax margin directly before investing:

A

wax pattern tends to release ito incorporated strain

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

Sprue size/gauge recommended for molar and metal ceramic patterns:

A

2.5mm (10-gauge)

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

Sprue size/gauge recommended for premolar castings and most partial-coveage restorations:

A

20.mm (12 gauge)

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

Where to attach sprue:

A

bulkiest, non critical part of the pattern, normally the largest non-functional cusp

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

Cusps for sprue, #30:

A

MB or ML cusps (?)

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

attach sprue w this:

A

sticky wax (goes in sprue as well)

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

to reinforce joint bw sprue and cusp and allow a smooth flow of molten alloy:

A

inlay wax

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

Attachment of sprue and crucible former:

A

wax pattern and sprue should be centered

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

TO avoid shrinkage porosity:

A

position a reservoir of the sprue at the heat center

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

Min distance to leave bw wax pattern and top of crucuble

A

6mm

28
Q

lid of crucible is __mm.

A

3mm

29
Q

is the reservoir typically closer to the crown or further from?

A

closer to

30
Q

Base of crucible is __mm.

A

3

31
Q

Types of investment materials:

A

gypsum, phosphate, or silica bonded

32
Q

investment material to use with metal alloys: ADA Type II, III, and IV:

A

gypsum bonded

33
Q

investment material to use with metal ceramic framework:

A

phosphate-bonded

34
Q

investment material to use with high-melting base metal alloys:

A

silica bonded

35
Q

Beauty cast is what type of investment?

A

gypsum bonded

36
Q

Spray mounted pattern w:

A

surfactant, gently blow excess liquid from pattern

37
Q

Trim this before burnout:

A

top glazed surface

38
Q

What to do if mold was allowed to set more than 12h:

A

rewet prior to burnout, soak 1-3m

39
Q

Removed this layer after burnout:

A

dense oxide layer

40
Q

Trim this once the investment has set and before burnout:

A

the “skin” (glassy part) at the top of the ring, remvoe rubber crucible former, place in oven

41
Q

Preheated oven for burnout is using this technique:r

A

apid technique

42
Q

Preheat temp for most alloys:

A

1200’F

43
Q

How long to heat the soak at final temperature for both rapid and standard techniques?

A

30m

44
Q

standard burnout technique:

A

cold oven, molds in oven at room temp, heat to desired temp at 25-40’F/ m

45
Q

For a complete casting, the casting force must be:

A

high enough to overcome the high surface tension of molten alloys, as well as the resistance of the gas within the mold.

46
Q

Casting force we use:

A

centrifugal force

47
Q

Heat sources for casting:

A

gas and compressed air torch, electricity

48
Q

steps to use gas and compressed air torch:

A

light gas, then turn on air flow valve

49
Q

zone within flame of torch:

A

unburnt gas –> burning gases (reducing atmosphere, hottest zone) –> burnt gas (oxidizing atmospheree)

50
Q

Direction and number of turns for casting anything but metal ceramic:

A

3, clockwise

51
Q

Direction and number of turns for casting metal ceramic:

A

4, clockwise

52
Q

Steps after winding arm and placing pin:

A

place crucible with preheated allop in machine, pull crucible away from cradle

53
Q

Function of the plux we sprinkle on alloy surface:

A

in fluidity, prevent or reduce oxidation (don’t add to metal ceramic alloy)

54
Q

Place casting ring with molten alloy here:

A

in cradle

55
Q

Use tongs to move:

A

crucible platform into contact w casting ring

56
Q

How to get the pin to drop and the arm to release:

A

pull arm forward

57
Q

Do this after red glow is gone from button

A

submerge casting ring in cold water, break off investment from the casting and clean w stiff brush

58
Q

How to clean casting:

A

ultrasonically

59
Q

Can cause rough casting:

A

excess surfactant, improper water/powder ratio, excessive burnout temp

60
Q

Can cause large nodules:

A

air trapped during investment procedure

61
Q

Can cause nodules on occ surface:

A

excessive vibration

62
Q

Can cause multiple nodules:

A

inadequate vacuum during investment, improper brush technique, lack of surfactant

63
Q

Can lead to fins:

A

inc water/powder ratio, pattern too near edge of investment, premature heating (mold still wet), too-rapid heating, dropped mold

64
Q

Can cause incomplete casting:

A

wax pattern too thin, cool mold, or inadequate heating, not enough metal, insufficient casting force

65
Q

Can cause suck-back porosity:

A

improper pattern position too narrow or too long sprue

indirect Restoration (54 decks)

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