Brainscape's Knowledge GenomeTM

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


See full index

Man Poo > Shell Molding-> Die Casting (C) > Flashcards

Shell Molding-> Die Casting (C) Flashcards

1
Q

What is SHELL MOLDING?

A

Cousin process to sand casting. A mold cavity surrounded by only a very thin layer of refractory material is prepared and filled with molten metal.

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

What must the PATTERNS used in SHELL MOLDING be made of?

A

METAL, unlike the wood or plastic used in sand casting.

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

Since METAL PATTERNS are expensive, when are they used?

A

They are used if large numbers of the same part are to be produced.

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

Why are METAL PATTERNS used in SHELL MOLDING?

A

Because it will be heated during the process steps and generally up to temps unsuitable for thermoplastics. They are usually organically shaped (not easy to 3D print from plastic).

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

How are the METAL PATTERNS made?

A

Sand Casting. Only one set of split patterns are required for the production of multiple parts.

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

What material is used for the SHELL MOLDS themselves?

A

A mixture of Zircon sand and thermosetting resin.

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

What is a DUMP BOX?

A

A box containing the sand and resin mixture and attached to the METAL PATTERN. The dump box is inverted, allowing this sand-resin mixture to coat the pattern. The heated pattern partially cures the mixture, which forms a shell around the pattern.

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

What are EJECTOR PINS?

A

Pins on the pattern plate are used to remove the shell from the plate.

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

What happens after two SHELLS have been made?

A

The two shells are assembled together in a container that is filled with support material, such as steel shot.

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

What are CORES in SHELL MOLDING?

A

CORES can be added to the mold cavity if CORE PRINTS were included in the METAL PATTERN.

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

What are the ADVANTAGES of SHELL MOLDING (over sand casting)?

A

Thin shells (fast cooling, flexible, good gas permeability), low sand volume (compared to sand casting), surface finish, lightweight, fewer flaws.

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

What are the DISADVANTAGES of SHELL MOLDING (over sand casting)?

A

Limited size and weight (thin walls can’t support large products), metal pattern (too expensive for one-time use), limited core complexity (especially if chaplets are needed).

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

What is INVESTMENT CASTING/LOST WAX CASTING?

A

An EXPENDABLE MOLD process that involves wax. Investment means to “DIP”.

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

What is WAX CARVING?

A

A process to make wax patterns. Usually for making items such as rings and jewelry with organic shapes. Done by a craftsman.

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

What is DIRECT 3D WAX PRINTING?

A

Designing them in 3D CAD modeling software and then printing out the WAX PATTERN with a 3D PRINTER designed for printing wax.

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

What is 3D PRINTING PLASTIC MOLDS?

A

Creating wax patterns indirectly using conventional 3D PRINTING of thermoplastics.

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

What is INJECTION MOLDING?

A

A method of creating plastic parts and wax patterns in very large numbers. However, the metal molds needed are very expensive.

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

What is a TREE in INVESTMENT CASTING?

A

An assembly of wax elements including the patterns, which will eventually become an entire casting system with a pouring basin, sprue, runners, and mold cavities.

19
Q

How are the TREES assembled?

A

By softening the individual elements with a fine gas torch and fusing them together.

20
Q

What are the TREES dipped into?

A

STUCCO or CERAMIC SLURRY. At first, it is dipped into a mixture of fine particles and water. Then it is dipped multiple times into a course particle mixture and less moisture. Once dry, it forms a thick ceramic SHELL.

21
Q

After DIPPING, why is the TREE placed into an oven?

A

To DRY and CURE the ceramic stucco, which provides strength and drives off moisture. The heating also serves to MELT OUT the wax from their surrounding ceramic shells.

22
Q

What is the result of MELT OUT?

A

The formation of a hollow shell, with internal passageways where the TREE used to be. The molten wax is collected and recycled.

23
Q

What is the METAL POUR step of SHELL MOLDING?

A

When the molten metal is poured into the mold.

24
Q

What is SHAKE OUT?

A

A method of separating the ceramic shell and the now metal tree.

25
Q

What is LOST FOAM CASTING/ EVAPORATIVE FOAM CASTING/ EXPANDED POLYESTERENE PROCESS?

A

A process similar to lost wax/ investment casting, but with STYROFOAM.

26
Q

What are the FOAM PATTERNS made of?

A

Expanded polystyrene

27
Q

What are the steps of the LOST FOAM CASTING?

A

The polystyrene pattern is dipped in refractory slurry. Then it is surrounded by loose unbonded sand and compacted by vibration. Metal is then poured onto the pattern. When the casting is solidified, it is removed from the flask and the sand is recycled.

28
Q

Why is there no separate MELT OUT step required in LOST FOAM CASTING?

A

The molten metal will vaporize the styrofoam upon contact.

29
Q

What is one of the best aspects of LOST FOAM CASTING?

A

Hollow parts can be made WITHOUT CORES.

30
Q

What is PERMANENT MOLD CASTING?

A

Casting processes where the mold can be utilized over and over again.

31
Q

What are PERMANENT MOLDS made out of?

A

A durable material such as TOOL STEEL or GRAPHITE. This limits this method to NON-FERROUS metals of substantially lower melting temps than the mold material.

32
Q

What is DIE CASTING?

A

The most sophisticated method of permanent mold casting. DIE CASTING utilizes metal molds for durability, but lacks breathability and collapsibility.

33
Q

What is a DIE?

A

A metal mold.

34
Q

What does applying HIGH PRESSURE do to the molten metal in the DIE CAVITY do?

A

It compensates for the deficiencies in breathability and collapsibility.

35
Q

What are the six attributes required for successful DIE CASTING?

A
  1. PRESSURIZED METAL INPUT (shot charge)
  2. VENTING/VALVE SYSTEM
  3. CLAMPING/LOCKING SYSTEM
  4. EJECTOR PIN SYSTEM
  5. CORE PULLS
  6. COOLING SYSTEM
36
Q

How is the PRESSURIZED INPUT of metal achieved?

A

By using a PISTON (straight cylinder) or PLUNGER (gooseneck system)

37
Q

What is the COLD CHAMBER method of die casting?

A

The COLD CHAMBER method requires the metal CHARGE to be placed in the SHOT TUBE (chamber) ahead of the piston. This is the preferred method for reactive metals to avoid the pitting of submerged parts.

38
Q

What is the HOT CHAMBER method of die casting?

A

The HOT CHAMBER method maintains a reservoir of molten metal as part of the machine.

39
Q

What is the VENTING/VALVE SYSTEM in DIE CASTING?

A

The die must have a temporary escape route for air already in the die to go to avoid misruns. The opening and closing of this VENTING SYSTEM must be coordinated with the position of the input piston/plunger.

40
Q

What is the CLAMPING/LOCKING SYSTEM in DIE CASTING?

A

A very large, hydraulically actuated CLAMPING SYSTEM is required to keep the two die halves closed, often used in conjunction with a mechanical TOGGLE LOCK.

41
Q

What is the EJECTOR PIN SYSTEM in DIE CASTING?

A

EJECTOR PINS are additional mechanical plungers used to pop out the walls of the die cavity and kick out the part.

42
Q

What are CORE PULLS?

A

Retractable metal CORES. Once the split die is closed, the CORES are pushed into the die cavity and the molten metal is injected. After solidification, the CORES are pulled out and the die reopened.

43
Q

What is the COOLING SYSTEM in DIE CASTING?

A

Complex artificial cooling is usually built into the dies through die passageways and out to an external radiator, heat exchanger, or even refrigeration unit.

44
Q

How can you tell if a part has been made by DIE CASTING?

A

The part would be:
- organically shaped
- made from non-ferrous metal
- have a smooth surface finish
- only have straight passageways
- small round indentations from ejector pins

Man Poo (31 decks)

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