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Fixed Pros 2020 > Investing and casting > Flashcards

Flashcards in Investing and casting Deck (15)
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1
Q

What is the purpose of the Sprue?

A
  • Allows molten and volatile wax to escape from the mold

- Allows molten metal to flow into the mold

2
Q

The metal within the sprue must remain molten slightly longer than what?

A

-The metal that has filled the mold

3
Q

What gauge of sprue do you use for a molar?

A

10 gauge

4
Q

T/F In general smaller sprues are better because it provides a better reservoir to remain molten

A

False

-Later sprues

5
Q

What do all investements have?

A
  • Binder Refractory material

- Modifier

6
Q

What does the refractory material do?

A

-Doesn’t burn or combust

7
Q

What is the most common simplest investment around used for gold?

A

-Gypsum bonded

8
Q

What is the problem with a gypsum bonded investment?

A

-If you heat it to much it will combust and burn up

9
Q

What is the phosphate bonded investment used for?

A

PFM

10
Q

T/F Stone and investments contract when setting

A

False,

-They both expand during setting

11
Q

T/F A casting that is slightly oversized is advantageous for accurate seating

A

True

12
Q

What are factors that increase expansion in gypsum bonded investments?

A
  • Decreased water/powder ratio
  • Prolonged spatulation
  • Water bath set (100 F for 1 hr immediately after investing
  • Use a dry ring liner
  • Use two ring liners
  • Use ringless investment technique
13
Q

What does adding water in gypsum bonded and phosphate bonded investments do?

A

-Decrease expansion

14
Q

What is quenching?

A

-Casting is placed in water when the button no longer has a red glow

15
Q

What does quenching result in?

A

-More malleable alloy