Permanent-Mold Casting Processes in Manufacturing Engineering

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What is a key advantage of permanent-mold casting over expendable mold processes?

The mold can be reused many times (correct)

It produces castings with a superior surface finish

It is more cost-effective for small production runs

It allows for more complex casting geometries

What materials are commonly used to construct permanent molds?

Steel and cast iron (correct)

Aluminum and magnesium alloys

Ceramic and graphite

Polymers and composites

Which of the following metals is NOT listed as commonly cast in permanent molds?

Magnesium

Aluminum

Copper-base alloys

Titanium (correct)

What type of cores can be used in permanent molds to form interior surfaces in the casting?

Either sand or metal cores Signup and view all the answers

What is the purpose of preheating and coating the mold in the permanent-mold casting process?

To ensure proper filling of the mold cavity Signup and view all the answers

What term is used when sand cores are used in a permanent mold?

Semi-permanent mold casting Signup and view all the answers

What is the purpose of preheating the mold in the permanent-mold casting process?

Facilitate metal flow through the gating system Signup and view all the answers

Why must the permanent mold be opened soon after the metal solidifies?

To prevent cracks from developing in the casting Signup and view all the answers

What is a key advantage of permanent-mold casting in terms of surface finish and dimensional control?

Results in a finer grain structure Signup and view all the answers

Why is die casting limited to metals of lower melting points?

Because it requires high-pressure injection into the mold cavity Signup and view all the answers

Which type of casting process is best suited for high-volume production due to mold cost considerations?

Die casting Signup and view all the answers

What are typical parts that are produced using permanent-mold casting?

Automotive pistons Signup and view all the answers

What is the primary distinguishing feature of the die casting process compared to other permanent mold casting processes?

The use of high pressure to force the metal into the die cavity Signup and view all the answers

What is the purpose of the piston in a hot-chamber die-casting machine?

To inject the liquid metal under high pressure into the die Signup and view all the answers

What is the main difference between hot-chamber and cold-chamber die-casting machines?

The method of injecting the molten metal into the cavity Signup and view all the answers

What is the typical sequence of steps in a die-casting cycle?

Melt metal, close die, inject metal, solidify, open die, eject part Signup and view all the answers

What is the purpose of maintaining pressure during solidification in the die-casting process?

To ensure the metal completely fills the die cavity Signup and view all the answers

What is the function of the die-casting machine in the die-casting process?

To hold and accurately close the two halves of the mold Signup and view all the answers

In cold-chamber die-casting machines, how is the molten metal initially introduced into the die cavity?

The molten metal is poured into an unheated chamber from an external melting container. Signup and view all the answers

Which of the following is NOT an advantage of die casting?

Complex geometries can be easily achieved. Signup and view all the answers

What is the primary purpose of the ram in the die casting process?

To maintain pressure on the molten metal during cooling and solidification. Signup and view all the answers

Which of the following statements about centrifugal casting is true?

The mold is rotated at high speed to distribute the molten metal evenly throughout the die cavity. Signup and view all the answers

What is the typical grain size of castings produced by die casting?

Small grain size due to rapid cooling. Signup and view all the answers

Which of the following casting methods is NOT mentioned in the text as part of the centrifugal casting group?

Investment casting Signup and view all the answers

What is the primary cause of mold crack according to the passage?

Insufficient mold strength Signup and view all the answers

What can happen when mold crack occurs?

Liquid metal can seep into the crack to form a fin on the final casting Signup and view all the answers

Which of the following is a method used to detect internal defects in a casting?

Radiographic methods, magnetic particle tests, fluorescent penetrants, and supersonic testing Signup and view all the answers

What is the purpose of mechanical testing on the cast metal?

To determine properties such as tensile strength and hardness Signup and view all the answers

What can be done if defects are discovered in a casting but are not too serious?

The casting can be saved by welding, grinding, or other salvage methods Signup and view all the answers