Learning Unit 3.2

Question 1

What is the advantage of using permanent mold casting?

Answer 1

Because of stable nature of mold, it can be used to produce large number of castings with the same mold.

Question 2

Name the characteristics of a permanent mold casting.

Answer 2

• It can be used to produce dimensionally accurate castings with close dimensional tolerances.
• The surface finish of the casting produces is very good.
• It is useful for small size castings.
• It is commonly employed for aluminum castings.
• The rate of production is high.
• The cast part is free from casting defects such as porosity, dirt and shrinkage.

Question 3

In shell-mold casting, what is the shell made of?

Answer 3

The shall consists of fine silica mixed with thermosetting resin such as phenol or urea formaldehyde.

Question 4

The process of investment casting is suitable for small-size casting with intricate details. Name 2 applications for this casting process

Answer 4

• Jewelries
• Dentistry’s
• Decorative items

Question 5

How is centrifugal casting completely different from all other casting processes?

Answer 5

It uses a rotating mold.

Question 6

What parts are being produced using g the true centrifugal casting process?

Answer 6

Hollow symmetrical parts such as:
- tubes
- pipes

Question 7

Name the characteristics of Die casting.

Answer 7

• Because of pressure being used in the process, it is suitable for making complex parts having several inner details. It is limited to small size castings.
• Dimensionally accurate parts can be produced by die casting. Cast parts sometimes do not require further machining.
• Zinc and aluminium are best cast by die casting because of their low melting points and
  better fluidity
• Die casting is of two types: hot chamber die casting land cold chamberldile casting.
• The furnace is the integral part of the hot chamber die casting, and the process is suitable for low melting point materials such as tin, lead, and zinc
• A separate furnace is used in cold chamber die casting, and the process is suitable for
  high melting point materials such as aluminium, magnesium and brass

Question 8

What are 2 parts that are traditionally produced using the plaster-mold casting process?

Answer 8

• Gears
• Valves

Question 9

What casting process is ideal for producing ornamental and decorative items?

Answer 9

Slush casting