Chapter 15

Question 1

In expendable molding

Answer 1

You just create and destroy a mold each time of use.

Question 2

Permanent mold casting or gravity die casting

Answer 2

Molds are made in segments, often hinged to périment rapid and curate opening and closing. After solidification the mold is opened and the product removed. The process can be repeated again as the mold is still hot.

Question 3

Semipermanent mold casting

Answer 3

When sand cores are used.

Question 4

Permanent mold casting is limited to

Answer 4

Lower melting point alloys, and high mold costs can make productions expensive.

Question 5

Mold life for permanent mold casting depends on:

Answer 5

1) the type of alloy being cast, higher melting point means shorter mold life. 2 the mold material, gray cast iron is usually used as it had the best resistance and machines easily. 3 pouring temperature. High pouring temps reduce mold life. 4 mold temperature, if the temp is too low you can expect mistuns, too high and erosion occurs.

Question 6

Mold cooling delay

Answer 6

May be needed before repeating another casting if the mold is too hot.

Question 7

Venting

Answer 7

Because the molds are not permeable, venting is used, typically through slick crack in the mold.

Question 8

Open mold when

Answer 8

After solidification to prevent the formats toon of hot fears.

Question 9

Tilt pour permanent mold casting

Answer 9

The mold is rotated into a horizontal position, and a cuo attach to the mold is filled with molten metal, it is then tilted and the it flows through the gating system to the mold. This reduces free fall and fat less turbulence

Question 10

Low pressure permanent mold and vacuum permanent mold casting

Answer 10

Mold is turned upside down and positioned above a sealed airtight chamber that contains. A crucible of molten material. A low pressure gas cause the molten metal to flow upward.

Question 11

In vacuum molding

Answer 11

The cleanliness of the metal and dissolved gas content are superior to that of lower pressure casting.

Question 12

Slush casting

Answer 12

Hollow castings are produced, hot metal Is poured and cooled, mold is inverted and remaining liquid is poured out. Good hollow shake, but variable wall thickness.

Question 13

Die casting, pressure die casting

Answer 13

Molten metal is fixed into preheated molds and held under pressure. Production rates highC good strength of profuctC and very intricate shapes.

Question 14

Retractable cores for die casting

Answer 14

Used to eject the finished casting.

Question 15

Die life

Answer 15

Limited by wear because of the temp of the molten metal.

Question 16

Heat checking

Answer 16

If temperature change is the cause of the die life dying, it is called this.

Question 17

Thermal fatigue

Answer 17

Is the die life dying is because of the number of cycles it is called this.

Question 18

In die casting, first

Answer 18

The mold cavity is first sprayed with a lubricant that helps control the temperature of the die and assists in its removal.

Question 19

Hot chamber of gooseneck

Answer 19

Partially submerged in a reservoir of molten metal, which flows through an open port and fills the chamber. Mechanical plunger applies pressure, and the metal is forced through the gooseneck to the rubber.

Question 20

Heated manifold direct injection due casting

Answer 20

The metal is fixed through a heated manifold and then through the heated mini nozzles directly into the die cavity. Scrap is reduced, energy conserved, product quality increased.

Question 21

Cold chamber machines

Answer 21

Used for materials not suitable for the hot chamber design. Alloys of aluminum, magnesium, copper. Metal is heated, then transferred to an unbeaten chamber, and then driven into the die by pressure.

Question 22

Risers not used in die casting because

Answer 22

The pressure ensures the continuous feed of molten metal from the gating system.

Question 23

Sand cores in die casting

Answer 23

Cant be used, they will disintegrate. Metal cores are used instead.

Question 24

Cast in inserts

Answer 24

Threader studs and other things can be incorporated. They are positioned before the lower melting temperature metal is injected.

Question 25

Pros and cons of die casting

Answer 25

No finish machining required, production rates are high. Most economical for large production volumes.

Question 26

Cost and quantity

Answer 26

You can justify the cost of die for mass production. For smaller production you can justify sand casting.