Permanent-Mold Casting Processes in Manufacturing Engineering
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Questions and Answers

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?

    <p>Either sand or metal cores</p> Signup and view all the answers

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

    <p>To ensure proper filling of the mold cavity</p> Signup and view all the answers

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

    <p>Semi-permanent mold casting</p> Signup and view all the answers

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

    <p>Facilitate metal flow through the gating system</p> Signup and view all the answers

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

    <p>To prevent cracks from developing in the casting</p> Signup and view all the answers

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

    <p>Results in a finer grain structure</p> Signup and view all the answers

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

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

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

    <p>Die casting</p> Signup and view all the answers

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

    <p>Automotive pistons</p> Signup and view all the answers

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

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

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

    <p>To inject the liquid metal under high pressure into the die</p> Signup and view all the answers

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

    <p>The method of injecting the molten metal into the cavity</p> Signup and view all the answers

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

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

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

    <p>To ensure the metal completely fills the die cavity</p> Signup and view all the answers

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

    <p>To hold and accurately close the two halves of the mold</p> Signup and view all the answers

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

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

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

    <p>Complex geometries can be easily achieved.</p> Signup and view all the answers

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

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

    Which of the following statements about centrifugal casting is true?

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

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

    <p>Small grain size due to rapid cooling.</p> 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?

    <p>Investment casting</p> Signup and view all the answers

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

    <p>Insufficient mold strength</p> Signup and view all the answers

    What can happen when mold crack occurs?

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

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

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

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

    <p>To determine properties such as tensile strength and hardness</p> Signup and view all the answers

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

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

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