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ISyE 350, Spring, 2006

Exam II

100 points

Name: ______

Part I: Multiple Choice. 3 points each. 33 points total. Circle the answer which is most correct.

1. Which of the following methods are effective at reducing porosity in a casting:

  1. Pour smoothly
  2. Heat molten metal as hot as possible before pouring
  3. Maximize turbulence of the molten metal as it enters mold
  4. a and b
  5. all of the above

2. Which of the following manufacturing processes is particularly well suited to mass producing small steel gears to net shape?

  1. Investment Casting
  2. Die Casting
  3. Sand Casting
  4. Powder Metallurgy
  5. Forging

3. Which of the following manufacturing processes tends to produce the strongest parts:

  1. Investment Casting
  2. Die Casting
  3. Sand Casting
  4. Powder Metallurgy
  5. Forging

4. Which of the following manufacturing processes is particularly well suited to mass producing complex aluminum parts to net shape:

  1. Investment Casting
  2. Die Casting
  3. Sand Casting
  4. Powder Metallurgy
  5. Forging

5. Which of the following parts would be well-suited to die casting?

  1. A 5 lb. cast-iron part at high volume
  2. A 500 lb. cast iron part at high volume
  3. A 5 lb. aluminum part at low volume
  4. A 500 lb. aluminum part at high volume
  5. A 5 lb. zinc part at high volume

6. An advantage of hot working over cold working is that hot working

  1. requires higher processing forces
  2. provides more ductility in the material
  3. is very suitable for forming sheetmetal
  4. produces better surface finish
  5. is enjoyable when the sun is out ;)

7. Which of these forming processes is best-suited to making long parts with a complex cross-section such as this:

  1. Hot rolling
  2. Cold rolling
  3. Deep drawing
  4. Roll forming
  5. Extrusion

8. Which of the following processes is the most economical for mass producing cup-shaped parts.

  1. Hot rolling
  2. Cold rolling
  3. Deep drawing
  4. Roll forming
  5. Extrusion

9. The We-Roll-It company wants to turn 1” thick steel slabs into 1/16” sheets with good surface finish. What manufacturing process(es) would be best?

  1. hot rolling
  2. cold rolling
  3. hot rolling followed by cold rolling
  4. cold rolling followed by hot rolling
  5. the Pillsbury process

10. Why are Powder Metallurgy parts limited in size to a few square inches in cross-section?

  1. The compaction press tonnage capacity is limited
  2. The injection cylinder can only inject a certain amount of molten metal
  3. Large P/M parts do not sinter properly
  4. Large P/M parts are too expensive

11. Which of the following manufacturing processes is the most common and versatile casting method:

  1. Permanent Mold Casting
  2. Die Casting
  3. Investment Casting
  4. Sand Casting
  5. Fly casting

Part II: Short Answer. 4 points each. 44 points total. Succinctly answer these questions. (A few words in some cases, a few sentences in others, sketches as needed/desired).

1.Casting and Powder Metallurgy are said to be “net shape” or “near-net shape” processes. What does “net shape” mean?

2.Briefly explain why casting tends to produce grains perpendicular to the mold wall.

3.In a casting, why is it desirable for solidification to start at the extremities of the mold and end at a riser?

4.Name 3 key disadvantages of hot working.

5.Why are permanent mold castings generally removed from the mold immediately after solidification has been completed?

6.Both Investment Casting and Die Casting produce accurate parts with excellent surface appearance. Name two key factors that would determine whether one method is preferred over the other.

7.In Powder Metallurgy, what additional challenge is there to making “tall” parts of high quality? (for example, a hollow cylinder with a length of 2”, an outer diameter of 1”, and an inner diameter of 0.5”)

8.Which manufacturing process would be best suited to making complexly shaped ferrous (iron, steel) parts, to a rough level of accuracy, at low volume?

9.Benny’s Bending Company is bending 12” squares of cold-rolled sheetmetal. They find that when they bend it along the x-x axis, it bends normally. But when they bend it along the y-y axis, it cracks. Why?

10.In casting, what are the benefits of not having to remove the pattern from the mold (e.g., investment casting)?

11.In Powder Metallurgy, why is a protective atmosphere (no oxygen) needed in the sintering operation?

Part III: Identification: 13 points

1. (10pts) For the mold shown below, label the components that have letters pointing to them:

Ostwald

2. (3 pts) What is the specific name for this manufacturing process?

Kalpakjian

Part IV: Problem Solving: 10 points

Calculate the dimensions of an effective riser for a casting that is a 1” x 3” x 6” rectangular plate. Assume that the casting and riser are not connected except by a gate and runner, and that the riser is a cylinder of height/diameter ratio H/D = 2.0.